A photoionization sensor for detecting gas concentration

Abstract

The present application discloses a photoionization sensor for detecting gas concentration, which is used to improve the detection accuracy of the photoionization sensor when expanding the concentration detection range. The present application includes: an ultraviolet lamp module, a sensor body, an ion current receiving electrode pair, an amplification circuit, and an output module; a gas flow area and an information processing area are provided on the sensor body; at least two ultraviolet light windows are provided on the ultraviolet lamp module, and the ultraviolet lamp module is arranged in the gas flow area, and the ultraviolet light windows are used to emit ultraviolet light after the ultraviolet lamp module generates an ultraviolet light source; at least two ion current receiving electrode pairs are installed in the gas flow area; at least two amplification circuits are installed in the information processing area, and the resistance in each amplification circuit is different, and the ion current receiving electrode pair is connected to the amplification circuit; the output module is arranged in the information processing area, and the output module is connected to the amplification circuit.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of detection, and in particular, to a photoionization sensor for detecting gas concentration. Background Art

[0002] The photoionization sensor is an important sensor for detecting gas substances at present. Its working principle is as follows: The gas to be detected absorbs photons emitted by an ultraviolet lamp that are higher than the ionization energy of the gas molecules to be detected, and is ionized into positive ions and electrons. Under the action of an external electrode, the ions move in space to form a weak current and are collected. This weak current is the photoionization current. The generated photoionization current is generally converted into a voltage value convenient for measurement through an amplifier circuit with a large resistance of about 10 9 Ω. Since the concentration of the gas to be detected is linearly related to the photoionization current within a certain range, the photoionization sensor can detect the concentration of the gas to be detected.

[0003] However, there is only one ultraviolet lamp module on the traditional photoionization sensor, corresponding to one ultraviolet light window, and there is only one amplifier circuit and output module on the photoionization sensor. Since the resistance of the amplifier circuit is fixed, there is a reliable detection range for the output voltage. The upper limit of this range is determined by the input voltage, and the lower limit is determined by the noise level of the detection device. Only within this detection range does the output voltage have sufficient accuracy. Currently, the method to increase the concentration detection range of the photoionization sensor is to newly add an ultraviolet lamp module, and add an amplifier circuit and output module with different amplification resistances to obtain another detection range.

[0004] However, in the method of adding an ultraviolet lamp module, when the two ultraviolet lamp modules work, the ultraviolet lamp modules ionize the gas to be detected by emitting light respectively, that is, the gas to be detected does not share the same ultraviolet light source for ionization. There are uncontrollable differences in various aspects such as the working gas concentration and purity of the ultraviolet light sources emitted by these two ultraviolet lamp modules, and the attenuation rate of the light intensity may also be different during long-term use. Therefore, the traditional method will reduce the detection accuracy when the photoionization sensor expands the measurement range during use. Summary of the Invention

[0005] The embodiments of the present application provide a photoionization sensor for detecting gas concentration, which is characterized by including:

[0006] An ultraviolet lamp module, a sensor main body, an ion current receiving electrode pair, an amplifier circuit, and an output module;

[0007] A gas flow area and an information processing area are provided on the sensor main body;

[0008] The ultraviolet lamp module is provided with at least two ultraviolet light windows. The ultraviolet lamp module is arranged in the gas flow area, and the ultraviolet light windows are used to emit ultraviolet light after the ultraviolet lamp module generates an ultraviolet light source.

[0009] At least two ion current receiving electrode pairs are installed in the gas flow area. The ion current receiving electrode pairs are placed in front of the ultraviolet light windows and are used to receive the signals generated when the gas to be measured is ionized.

[0010] At least two amplifier circuits are installed in the information processing area. The resistance values in each amplifier circuit are different. The ion current receiving electrode pairs are connected to the amplifier circuits, and the amplifier circuits are used to process the signals collected by the ion current receiving electrode pairs.

[0011] The output module is arranged in the information processing area. The output module is connected to the amplifier circuits and is used to receive and obtain the gas concentration information of the gas to be measured based on the signals processed by the amplifier circuits.

[0012] Optionally, the ultraviolet lamp module includes an AC voltage module, an ultraviolet light window, an ultraviolet excitation electrode pair, an ultraviolet lamp body, and a working gas.

[0013] At least two ultraviolet light windows are arranged on the ultraviolet lamp body.

[0014] The ultraviolet lamp body contains a working gas and emits ultraviolet light under the excitation of the ultraviolet excitation electrode pair.

[0015] The ultraviolet excitation electrode pair is installed on the ultraviolet lamp body and is used to excite the working gas to generate an ultraviolet light source.

[0016] The AC voltage module is connected to the ultraviolet excitation electrode pair, and the AC voltage module is used to provide a high-voltage AC voltage to the ultraviolet excitation electrode pair.

[0017] Optionally, the AC voltage module includes a high-voltage power supply module and a high-voltage power conversion module.

[0018] The high-voltage power supply module is connected to the high-voltage power conversion module.

[0019] The high-voltage power conversion module is connected to the ultraviolet excitation electrode pair, and the high-voltage power conversion module is used to supply electrical energy to the ultraviolet excitation electrode pair.

[0020] Optionally, the ultraviolet lamp module further includes a gas adsorbent.

[0021] The ultraviolet lamp module contains a gas adsorbent, and the gas adsorbent is used to adsorb the impurity gas in the ultraviolet lamp module.

[0022] Optionally, the gas flow area includes an air inlet, an air outlet, and an ionization area.

[0023] The air inlet is provided on the sensor body, and the gas to be measured enters the ionization region through the air inlet, and the gas to be measured is ionized in the ionization region;

[0024] The exhaust port is provided on the sensor body, and the exhaust port is used to evacuate the gas to be measured from the ionization region.

[0025] Optionally, the gas flow region further includes an air pump for pumping the gas to be measured into the ionization region.

[0026] Optionally, the gas flow region further includes an exhaust pump for exhausting the gas to be measured from the ionization region.

[0027] Optionally, the ion current receiving electrode pair is placed parallel to the ultraviolet light window.

[0028] Optionally, the ion current receiving electrode pair is placed perpendicular to the ultraviolet light window.

[0029] Optionally, the output module includes a logic judgment module and an information output module;

[0030] The logic judgment module is connected to the amplifier circuit, and the logic judgment module is used to analyze the signal processed by the amplifier circuit;

[0031] The logic judgment module is connected to the information output module, and the information output module is used to output the gas concentration information of the gas to be measured.

[0032] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0033] A plurality of ultraviolet light windows are simultaneously provided on the same ultraviolet lamp module. Each ultraviolet light window ionizes the gas to be measured by emitting ultraviolet light. The signal generated during the ionization of the gas to be measured is received by a plurality of ion current receiving electrode pairs. The ion current receiving electrode pair transmits the signal to the amplifier circuit for information processing, and the output module receives the information transmitted by a plurality of amplifier circuits for logical analysis and calculation of the gas concentration of the gas to be measured. In the embodiments of the present application, each amplifier circuit uses a different amplification resistance to obtain different current amplification gains. The high-gain amplifier circuit has a smaller zero-point noise and a smaller saturation concentration, and the low-gain amplifier circuit has a larger zero-point noise and a larger saturation concentration. A smaller zero-point noise means reliable detection of lower-concentration chemical gases. Therefore, the reliable detection range of each amplifier circuit is different. By selecting appropriate differential amplification resistances to connect the reliable detection ranges, the total reliable detection range of the photoionization sensor is increased. And a plurality of ultraviolet light windows are provided on the same ultraviolet lamp module. Each ultraviolet light window shares an ultraviolet light source. The ultraviolet light source, gas concentration, purity, etc. of each ultraviolet light window are almost the same, and the possible attenuation of the light intensity during long-term use also has consistency. Therefore, the detection accuracy is improved when the photoionization sensor expands its measurement range. Description of the Drawings

[0034] Figure 1 Schematic structural diagram of an embodiment of a photoionization sensor for detecting gas concentration;

[0035] Figure 2 Test chart of the response amplitudes of high- and low-gain amplifier circuits to IBE gases at different concentrations in a photoionization sensor with a double-ultraviolet lamp window;

[0036] Figure 3 Concentration conversion chart of the high-gain amplifier circuit in a photoionization sensor with a double-ultraviolet lamp window for low-concentration IBE gases;

[0037] Figure 4 Concentration conversion chart of the high-gain amplifier circuit in a photoionization sensor with a double-ultraviolet lamp window for high-concentration IBE gases;

[0038] Figure 5 Concentration conversion chart of the low-gain amplifier circuit in a photoionization sensor with a double-ultraviolet lamp window for low-concentration IBE gases;

[0039] Figure 6 Concentration conversion chart of the low-gain amplifier circuit in a photoionization sensor with a double-ultraviolet lamp window for high-concentration IBE gases;

[0040] Figure 7 Schematic structural diagram of an embodiment of an ultraviolet lamp module;

[0041] Figure 8 Schematic structural diagram of another embodiment of an ultraviolet lamp module;

[0042] Figure 9 Schematic structural diagram of another embodiment of an ultraviolet lamp module;

[0043] Figure 10 Schematic structural diagram of another embodiment of a photoionization sensor for detecting gas concentration;

[0044] Figure 11 Schematic structural diagram of an embodiment of the positional relationship between an ultraviolet lamp and an ion current receiving electrode pair;

[0045] Figure 12 Schematic structural diagram of another embodiment of the positional relationship between an ultraviolet lamp and an ion current receiving electrode pair. Detailed Description of the Invention

[0046] The technical solutions in the present application will be clearly and completely described below in conjunction with the accompanying drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the protection scope of the present application.

[0047] In the embodiments of the present application, a photoionization sensor is involved. The photoionization sensor is a sensor with extremely high sensitivity and wide applications, which can detect volatile organic compounds and other toxic gases with concentrations ranging from about 10 ppb to about 10,000 ppm. Many harmful substances contain volatile organic compounds, and the photoionization sensor is efficient and reliable in detecting volatile organic compounds.

[0048] The gas to be detected absorbs photons emitted by an ultraviolet lamp that are higher than the ionization energy of the gas molecules to be detected, and is ionized into positive ions and electrons. Under the action of an external electrode, the ions move in space to form a weak current, which is collected. This weak current is the photoionization current. The generated photoionization current is generally converted into a voltage value convenient for measurement through an amplifier circuit with a large resistance of about 10 9 Ω. Since the concentration of the gas to be detected is linearly related to the photoionization current within a certain range, the photoionization sensor can detect the concentration of the gas to be detected.

[0049] However, there is only one ultraviolet lamp module on the traditional photoionization sensor, corresponding to one ultraviolet light window, and there is only one amplifier circuit and output module on the photoionization sensor. Since the resistance of the amplifier circuit is fixed, there is a reliable detection range for the output voltage. The upper limit of this range is determined by the input voltage, and the lower limit is determined by the noise level of the detection device. Only within this detection range does the output voltage have sufficient accuracy. Currently, the method for increasing the concentration detection range of the photoionization sensor is to newly add an ultraviolet lamp module, and add an amplifier circuit and an output module with different amplification resistances to obtain another detection range.

[0050] However, in the method of adding an ultraviolet lamp module, when the two ultraviolet lamp modules work, the ultraviolet lamp modules respectively emit light to ionize the gas to be detected, that is, the gas to be detected does not share the same ultraviolet light source for ionization. There are uncontrollable differences in various aspects such as the working gas concentration and purity of the ultraviolet light sources emitted by these two ultraviolet lamp modules, and the attenuation rate of the light intensity may also be different during long-term use. Therefore, the traditional method will reduce the detection accuracy when the photoionization sensor expands the measurement range during use.

[0051] The embodiments of the present application disclose a photoionization sensor for detecting gas concentration, which is used to improve the detection accuracy when the photoionization sensor expands the concentration detection range.

[0052] Please refer to Figure 1 , an embodiment of the present application provides a photoionization sensor for detecting gas concentration, including:

[0053] An ultraviolet lamp module 1, a sensor body 2, an ion current receiving electrode pair 3, an amplifier circuit 4, and an output module 5;

[0054] A gas flow area and an information processing area are provided on the sensor body 2;

[0055] At least two ultraviolet light windows are provided on the ultraviolet lamp module 1. The ultraviolet lamp module 1 is arranged in the gas flow area, and the ultraviolet light windows are used to emit ultraviolet light after the ultraviolet lamp module 1 generates an ultraviolet light source;

[0056] At least two ion current receiving electrode pairs 3 are installed in the gas flow area. The ion current receiving electrode pair 3 is placed in front of the ultraviolet light window, and the ion current receiving electrode pair 3 is used to receive the signal generated when the gas to be measured is ionized;

[0057] At least two amplifier circuits 4 are installed in the information processing area. The resistance in each amplifier circuit 4 is different. The ion current receiving electrode pair 3 is connected to the amplifier circuit 4, and the amplifier circuit 4 is used to process the signal collected by the ion current receiving electrode pair 3;

[0058] The output module 5 is arranged in the information processing area. The output module 5 is connected to the amplifier circuit 4, and the output module 5 is used to receive and obtain the gas concentration of the gas to be measured according to the signal processed by the amplifier circuit 4.

[0059] Figure 1 Taking the photoionization sensor with double ultraviolet light windows as an example, first, the structure of the photoionization sensor with double ultraviolet light windows and the functions of its structure will be described below:

[0060] The photoionization sensor with double ultraviolet light windows has a sensor body 2. The sensor body 2 is a sensor housing, which is used to install other detection components and provide a detection space for the gas to be measured. The sensor body 2 can be divided into two areas: a gas flow area and an information processing area. The devices in the gas flow area are an ultraviolet lamp module 1 and an ion current receiving electrode pair 3, and the devices in the information processing area are an amplifier circuit 4 and an output module 5.

[0061] In practical applications, the gas to be measured needs to be introduced into the gas flow area, and the gas to be measured is ionized by the ultraviolet lamp module 1. The information processing area is used for data processing.

[0062] The ultraviolet lamp module 1 is a device for generating an ultraviolet light source. In the photoionization sensor with dual ultraviolet windows, the ultraviolet lamp module 1 is provided with two ultraviolet windows 7. Since the ultraviolet lamp module 1 can only generate one ultraviolet light source, the two ultraviolet windows 7 share the same ultraviolet light source. The two ultraviolet windows 7 share the same ultraviolet light source, which can reduce the differences in ultraviolet light sources, gas concentration, purity, etc. Compared with the photoionization sensor using multiple ultraviolet lamp modules, the photoionization sensor with dual ultraviolet windows uses only one ultraviolet light source, and the conditions of the gas to be measured ionized by the two ultraviolet windows 7 are closer, and the error of the collected data is smaller.

[0063] The ion current receiving electrode pair 3 is composed of two electrode plates. In the photoionization sensor with dual ultraviolet windows, two ion current receiving electrode pairs 3 are provided to respectively collect ions generated by the gas to be tested ionized by the two ultraviolet windows 7, thereby forming a weak current signal (photoionization current). The ion current receiving electrode pair 3 transmits the collected weak current signal (photoionization current) to the amplifier circuit 4.

[0064] In the photoionization sensor with dual ultraviolet windows, two amplifier circuits are provided. The two amplifier circuits 4 are used to respectively receive the weak current signals formed by the two ion current receiving electrode pairs 3, and amplify the weak current signals (photoionization current) into a voltage signal, which is finally transmitted to the output circuit 5 by the amplifier circuit 4.

[0065] In the photoionization sensor with double ultraviolet windows, an output module 5 is provided, and the output module 5 is used to receive the analog outputs transmitted by the two amplifying circuits 4, perform logic analysis and calculation, and obtain the gas concentration of the gas to be measured.

[0066] The following is an explanation of the operating principle of the amplifier circuit 4 and the defects that exist during its use:

[0067] When the photoionization current I enters the amplifier circuit 4 from the ion current receiving electrode pair 3, it will be amplified by a larger resistor R, and the voltage in the high-resistance state will be converted into the voltage in the low-resistance state by an operational amplifier driver. According to the relationship V=IR, the voltage between the output and input ends of the amplifier circuit 4, i.e., the amplified voltage, can be measured. The amplified voltage obtained by this method is a low-resistance voltage, which can be used for external circuit output and measurement. In this embodiment, the low-resistance voltage is used to transmit the ionization information of the gas to be measured.

[0068] Due to the characteristics of the op-amp drive, there are problems with the amplified voltage at the output. When the concentration of the gas to be measured increases, resulting in an increase in the ion current I, for a given amplifier circuit 4, since the resistance value set inside it cannot be adjusted, after the IR value approaches the voltage input value of the op-amp, the amplified voltage output value of the op-amp cannot continue to increase, thus causing saturation of the output of the photoionization sensor. If the R value of the amplifier circuit is small, during the detection process, the generated ion current I value is also small. When the ion current I value is only in the pA to nA level, the signals generated by low-concentration gases to be measured are easily submerged by circuit and environmental noise. Therefore, when setting up the amplifier circuit 4, it is necessary to consider the reliability of the signal and the limitations of the circuit design. The detectable dynamic range of the amplifier circuit 4 is about 10 3 -10 4 . This results in a defect of insufficient sensitivity or output saturation when the concentration of the gas to be measured is not within the preset range of this amplifier circuit 4 during use.

[0069] The following describes the use of the amplifier circuit 4 in a photoionization sensor with a double ultraviolet light window in conjunction with the attached drawings:

[0070] This embodiment takes the photoionization sensor with a double ultraviolet lamp window as an example, and uses isobutene (IBE) and ammonia for concentration range testing. The ratio of the full-scale signal output by the amplifier circuit to the noise is about 1 to 1×10 4 . The carrier gas of IBE is nitrogen, and the test concentration range is about 0.1 ppm to 5000 ppm. In this embodiment, the low-gain resistor is 0.1 GΩ, the high-gain resistor is 10 GΩ, and the other parts are the same. The saturated output voltage of the op-amp is 5V.

[0071] Figure 2 Shows the response amplitudes of the photoionization sensor device with a double ultraviolet window to IBE gases of 0.1, 0.3, 1, 10, 30, 100, 300, 1000, 2000, and 5000 ppm, and the output is the voltage value. From Figure 2 it can be observed that the high-gain (amplifier circuit with a large resistor) end saturates after 100 ppm, and the output value remains at the highest range. The low-gain (amplifier circuit with a small resistor) end shows an obvious response only after the concentration exceeds 100 ppm. From Figure 2 it can be seen that for the photoionization sensor device with a high-gain double ultraviolet window, there will be an obvious response to low-concentration IBE gases, but when detecting higher-concentration IBE gases, there will be a situation where the amplifier circuit saturates. For the photoionization sensor device with a low-gain double ultraviolet window, the response to low-concentration IBE gases is not obvious, but when detecting high-concentration IBE gases, the response increases significantly. This indicates that when the resistance of the amplifier circuit cannot be changed, there will be a phenomenon of saturation in a certain concentration range of detection or a decrease in detection accuracy.

[0072] Figure 3 and Figure 4 specifically shows the error situation at high gain. From Figure 3 it can be seen that at low concentrations of IBE gas (0.1 - 10 ppm), high gain has always maintained a very low error range. At 0.1 ppm, the signal - to - noise ratio is 10, meeting the quantitative accuracy requirements. At Figure 4 , the test concentration of 30 ppm is relatively accurate and the error is small, but it has been saturated after 100 ppm. Although the error is zero, the accurate concentration cannot be obtained.

[0073] Figure 5 and Figure 6 specifically shows the error situation at low gain. At Figure 5 , although an output is obtained for low - concentration detection, the error is very large. Even before 3 ppm, it is less than 3 times the noise level and is an untrustworthy signal. The signal - to - noise ratio only meets the quantitative requirements at 10 ppm. At Figure 6 , it can be seen that although the absolute noise value of low gain is high, due to the large measured concentration, the relative signal - to - noise ratio is very high, and it can also respond to high - concentration IBE. However, since high - concentration IBE reduces the penetration ability of ultraviolet light, the ionization efficiency of the overall gas decreases, resulting in the conversion value based on voltage being lower than the actual concentration. Therefore, non - linear correction is required for this part.

[0074] It can be seen from the above embodiments that traditional single - ultraviolet - light - window photoionization sensors can only measure concentrations within a certain detection range with high precision. Beyond this detection range, the measurement accuracy will decrease.

[0075] Therefore, in order to expand the measurable range of the photoionization sensor, a photoionization sensor with a double - ultraviolet - light - window is adopted in this embodiment. A set of ion - current receiving electrode pairs 3 is installed at each ultraviolet - light window 7. Multiple groups of electrodes respectively correspond to independent amplifier circuits 4, and the resistances of these amplifier circuits 4 are different. During detection, when the high - gain (large - resistance) end is not saturated (the output value is less than the operational - amplifier input voltage value), the output circuit takes the output of this end as the standard and calculates the corresponding gas concentration; when the high - gain (large - resistance) end is saturated (the output value is greater than or equal to the operational - amplifier input voltage value), the output circuit takes the output of the low - gain (small - resistance) end as the standard and outputs the calculated voltage value according to the calibration relationship between voltage and concentration. By setting amplifier circuits with different resistances on the photoionization sensor, the purpose of expanding the measurable range of the photoionization sensor is achieved.

[0076] However, the traditional photoionization sensor with double ultraviolet light windows is realized by connecting multiple ultraviolet lamp modules in series. Using multiple ultraviolet lamp modules means introducing multiple ultraviolet light sources. There are uncontrollable differences in various aspects such as the gas concentration and purity of the ultraviolet lamp modules. Moreover, during use, the attenuation rates such as air leakage of different ultraviolet lamp bodies are also different. Therefore, there are many initial matching problems and calibration problems during the combined use, and there may be additional maintenance problems in the later stage. This results in a problem of decreased detection accuracy during the use of the traditional photoionization sensor with double ultraviolet light windows.

[0077] Therefore, to solve the problems existing in the traditional photoionization sensor with double ultraviolet light windows, in this embodiment, multiple ultraviolet light windows are provided on one ultraviolet lamp module, which enables multiple ultraviolet light windows to share the same ultraviolet light source during the detection process, solves the problems existing in the traditional photoionization sensor with double ultraviolet light windows, and improves the detection accuracy when the photoionization sensor expands the measurement range.

[0078] The following is an explanation of the structure and function of the ultraviolet lamp module 1:

[0079] Please refer to Figure 7 , this embodiment of the present application provides an ultraviolet lamp module, including:

[0080] Optionally, the ultraviolet lamp module 1 includes an AC voltage module 6, an ultraviolet light window 7, an ultraviolet excitation electrode pair 8, an ultraviolet lamp body 9, and a working gas 10;

[0081] At least two ultraviolet light windows 7 are provided on the ultraviolet lamp body 9;

[0082] The ultraviolet lamp body 9 contains a working gas and emits ultraviolet light under the excitation of the ultraviolet excitation electrode pair 8;

[0083] The ultraviolet excitation electrode pair 8 is installed on the ultraviolet lamp body 9, and the ultraviolet excitation electrode pair 8 is used to excite the working gas 10 to generate an ultraviolet light source;

[0084] The AC voltage module is connected to the ultraviolet excitation electrode pair 8, and the AC voltage module 6 is used to provide a high-voltage AC voltage to the ultraviolet excitation electrode pair 8.

[0085] In this embodiment, taking the ultraviolet lamp module with double ultraviolet light windows as an example, the structure of the ultraviolet lamp module 1 is described.

[0086] The ultraviolet lamp body 9 is the framework of the ultraviolet lamp module 1. The material of the ultraviolet lamp body 9 is mainly glass, and its shape needs to be determined according to the manufacturing process. In this embodiment, the ultraviolet lamp body 9 of the ultraviolet lamp module with double ultraviolet light windows is cylindrical. The ultraviolet lamp module 1 forms a low-pressure sealed state. The interior of the ultraviolet lamp body 9 is filled with a specific working gas 10. When the working gas 10 is excited by high-frequency alternating current, it can generate a plasma discharge phenomenon to emit light, thereby generating ultraviolet light. The working gas 10 can be various rare gases, which is not limited here. The manufacturing material of the ultraviolet light window 7 can be MgF2, CaF2, LiF, etc., which is not limited here. Since the plasma state of the working gas is easily quenched by other impurity gases, the ultraviolet lamp module 1 is made into a low-pressure sealed state.

[0087] An ultraviolet excitation electrode pair 8 is also provided on the ultraviolet lamp module with double ultraviolet light windows. The ultraviolet excitation electrode pair 8 has two electrodes. The ultraviolet excitation electrode pair 8 is used to excite the working gas 10 so that the working gas 10 emits an ultraviolet light source. Among them, the ultraviolet excitation electrode pair 8 is connected to the alternating voltage module 6, and the alternating voltage module 6 supplies a high-voltage alternating voltage to the ultraviolet excitation electrode pair 8 to create an alternating electric field environment. In such an electric field environment, the working gas 10 will emit an ultraviolet light source, and the ultraviolet light source is emitted through the two ultraviolet light windows 7.

[0088] In this embodiment, the material of the ultraviolet excitation electrode pair 8 can be metals such as Cu or Au, or other materials with a conductive coating, which is not limited here.

[0089] The manufacturing process of the ultraviolet lamp module 1 will be described below:

[0090] In the embodiment of the present application, taking the ultraviolet lamp module with double ultraviolet light windows as an example, the manufacturing process of the ultraviolet lamp module 1 will be described.

[0091] In the ultraviolet lamp module with double ultraviolet light windows, the ultraviolet lamp body 9 is a cylindrical glass tube. One ultraviolet lamp mounting opening of the cylindrical glass tube is first bonded to the ultraviolet light window 7 with a low-temperature glass powder or other substances at high temperature to achieve a semi-open and semi-closed structure. The material of the ultraviolet light window 7 here is magnesium fluoride. Subsequently, low-temperature glass powder or other substances are added to the other ultraviolet lamp mounting opening of the cylindrical glass tube, and the above device is sealed in a low-pressure environment filled with the working gas 10. The working gas 10 here is krypton gas, and the pressure is about 300 Pa. Subsequently, it is heated to the working temperature of the low-temperature glass powder and pasted to achieve the sealing of the working gas 10 and the bonding of the ultraviolet light window. Subsequently, it is cooled and connected to the atmosphere. After installing the ultraviolet excitation electrode pair 8, the manufacturing of the ultraviolet lamp module 1 with double windows is completed.

[0092] Please refer to Figure 8 and Figure 9, It should be noted that, in addition to the photoionization sensor with a dual ultraviolet light window, theoretically, it is also possible to fabricate photoionization sensors with more ultraviolet light windows. Figure 8 Figure 222 is a structural diagram of an ultraviolet lamp module with three ultraviolet light windows. Figure 8 Figure 223 is a structural diagram of an ultraviolet lamp module with four ultraviolet light windows. Theoretically, by fabricating an ultraviolet lamp module with multiple ultraviolet light windows, a corresponding photoionization sensor can be fabricated, increasing the detection range and detection accuracy of the photoionization sensor.

[0093] Please refer to Figure 10 , The structure of the photoionization sensor will be described in detail below:

[0094] Optionally, the AC voltage module 6 includes a high-voltage power supply module 11 and a high-voltage power conversion module 12;

[0095] The high-voltage power supply module 11 is connected to the high-voltage power conversion module 12;

[0096] The high-voltage power conversion module 12 is connected to the ultraviolet excitation electrode pair 8, and the high-voltage power conversion module 12 is used to supply electrical energy to the ultraviolet excitation electrode pair 8.

[0097] In this embodiment, the AC voltage module 6 is divided into two parts. One is the high-voltage power supply module 11, which provides high-voltage electrical energy during operation. The other is the high-voltage power conversion module 12, which converts the high-voltage power provided by the high-voltage power supply module 11 into a high-voltage AC voltage, so that the ultraviolet excitation electrode pair 8 obtains the high-voltage AC voltage.

[0098] Optionally, the ultraviolet lamp module 1 further includes a gas adsorbent;

[0099] The ultraviolet lamp module 1 contains a gas adsorbent, and the gas adsorbent is used to adsorb impurity gases in the ultraviolet lamp module 1.

[0100] In this embodiment, the gas adsorbent can be an alloy material of Zr, Al, and V, which is not limited here. During the fabrication and use of the ultraviolet lamp module 1, impurity gases may penetrate into the working gas, and the gas adsorbent will adsorb the impurity gases inside the ultraviolet lamp module 1.

[0101] Optionally, the gas flow region includes an air inlet 13, an air outlet 14, and an ionization region 15;

[0102] The air inlet 13 is provided on the sensor body 2, and the gas to be measured enters the ionization region 15 through the air inlet 13, and the gas to be measured is ionized in the ionization region 15;

[0103] The air outlet 14 is provided on the sensor body 2, and the air outlet 14 is used to evacuate the gas to be measured from the ionization region 15.

[0104] An air inlet 13 and an air outlet 14 are provided in the gas flow region, and the air inlet 13 and the air outlet 14 introduce the gas to be measured into the ionization region 15. Among them, the method of introducing the gas to be measured into the ionization region 15 is mainly the active pump suction method or the passive diffusion method. The passive diffusion method is to change the concentration gradient difference between the inside and outside of the air inlet 13, so that the gas to be measured expands through the air inlet 13 to the ionization region 15. When the detection is completed, by changing the concentration gradient difference between the inside and outside of the air outlet 14, the gas to be measured expands from the ionization region 15 through the air outlet 14 to the outside. The active pump suction method is to install an air pump on the air outlet 14 or the air inlet 13, and the air pump is used to make the gas to be measured enter the ionization region 15 and discharge from the ionization region 15. For the diffusion detection or the pump suction detection, the flow rate is 50 - 1000 mL / min, preferably in the range of 100 - 400 mL / min.

[0105] The following is an explanation of the active pump suction method:

[0106] Optionally, the gas flow region further includes a suction pump for pumping the gas to be measured into the ionization region.

[0107] Optionally, the gas flow region further includes an exhaust pump for discharging the gas to be measured from the ionization region.

[0108] In this embodiment, the air pump can be divided into a suction pump 16 and an exhaust pump 17 according to the installation position. The suction pump 16 is used to pump the gas to be measured into the ionization region 15, and the exhaust pump 17 is used to discharge the gas to be measured from the ionization region 15. On the same photoionization sensor, only one of the suction pump 16 and the exhaust pump 17 needs to be set to achieve the purpose of the active pump suction method, or the suction pump 16 and the exhaust pump 17 can be installed at the same time, which is not limited here.

[0109] Optionally, the output module 5 includes a logic judgment module 18 and an information output module 19;

[0110] The logic judgment module 18 is connected to the amplifier circuit 4, and the logic judgment module 18 is used to analyze the signal generated by the amplifier circuit 4;

[0111] The logic judgment module 18 is connected to the information output module 19, and the information output module 19 is used to output the gas concentration of the gas to be measured.

[0112] In this embodiment, the logic judgment module 18 and the information output module 19 are mainly used to perform logical judgment on the electrical signal sent by the amplifier circuit 4. When the small-range amplifier circuit 4 is saturated, the logic judgment module 18 will use the electrical signal sent by the unsaturated amplifier circuit 4 with a different range as the basic data for calculating the concentration.

[0113] Please refer toFigure 11 and Figure 12 Next, the placement positions of the ion current receiving electrode pair 3 and the ultraviolet light window 7 will be described:

[0114] Optionally, the ion current receiving electrode pair 3 is placed parallel to the ultraviolet light window 7.

[0115] Optionally, the ion current receiving electrode pair 3 is placed perpendicular to the ultraviolet light window 7.

[0116] Currently, in a photoionization sensor, the ion current receiving electrode pair 3 and the ultraviolet light window 7 have different position installation methods. Figure 11 shows a design where the positive and negative electrodes are parallel to the ultraviolet light emission direction, Figure 12 shows a design where the positive and negative electrodes are perpendicular to the ultraviolet light emission direction. When using the Figure 12 design method, there should be a light passing hole on the electrode close to the ultraviolet light window 7 so that the ultraviolet light can pass through the electrode to reach between the two electrodes. In Figure 11 and Figure 12 , the ultraviolet light source emits through the ultraviolet light window 7, and the emitted ultraviolet light direction is parallel upward. The ultraviolet light source of a common photoionization sensor is realized by the plasma luminescence of rare gases, and these ultraviolet lights are emitted through the transparent layer of the ultraviolet light source. The light source of a common photoionization sensor is cylindrical at the ultraviolet transparent layer end. The purpose of the external light source is to ionize the gas molecules to be measured between the ionization regions 15. In Figure 11 and Figure 12 , the ion current receiving electrode pair 3 has positive and negative poles, which are used to generate an electric field to collect the ions of the gas molecules to be measured that have been ionized. In Figure 11 , the air flow direction in the ionization region 15 can be perpendicular to the paper surface, and can enter the ionization region 15 through the micropores on the ion current receiving electrode pair 3, perpendicular to the positive and negative electrodes of the ion current receiving electrode pair 3, or flow from top to bottom or from bottom to top parallel to the ultraviolet light direction. Figure 12 In

[0117] In this application, terms such as "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only used to illustrate the relative position relationship between each component or component part, and do not particularly limit the specific installation orientation of each component or component part.

[0118] Moreover, in addition to being used to indicate orientation or positional relationship, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0119] In addition, the terms "installed", "set up", "provided with", "connected", and "linked" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, components, or parts. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0120] In addition, the structures, proportions, sizes, etc. depicted in the drawings in this application are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the conditions for the implementation of this application. Therefore, they do not have technical substantial significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that this application can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in this application.

Claims

1. A photoionization sensor for detecting gas concentration, characterized in that, Comprising: An ultraviolet lamp module, a sensor body, an ion current receiving electrode pair, an amplifier circuit, and an output module; A gas flow area and an information processing area are provided on the sensor body; At least two ultraviolet light windows are provided on the ultraviolet lamp module, the ultraviolet lamp module is disposed in the gas flow area, and the ultraviolet light windows are used to emit ultraviolet light after the ultraviolet lamp module generates an ultraviolet light source; At least two of the ion current receiving electrode pairs are installed in the gas flow area, the ion current receiving electrode pairs are placed in front of the ultraviolet light windows, and the ion current receiving electrode pairs are used to receive signals generated when the gas to be measured is ionized; At least two of the amplifier circuits are installed in the information processing area, the resistance values in each amplifier circuit are different, the ion current receiving electrode pairs are connected to the amplifier circuits, and the amplifier circuits are used to process the signals collected by the ion current receiving electrode pairs; The output module is disposed in the information processing area, the output module is connected to the amplifier circuit, and the output module is used to receive and obtain the gas concentration information of the gas to be measured according to the signals processed by the amplifier circuit; The ultraviolet lamp module includes an AC voltage module, an ultraviolet light window, an ultraviolet excitation electrode pair, an ultraviolet lamp body, and a working gas; At least two ultraviolet light windows are provided on the ultraviolet lamp body; The ultraviolet lamp body contains the working gas and emits ultraviolet light under the excitation of the ultraviolet excitation electrode pair; The ultraviolet excitation electrode pair is installed on the ultraviolet lamp body, and the ultraviolet excitation electrode pair is used to excite the working gas to generate an ultraviolet light source; The AC voltage module is connected to the ultraviolet excitation electrode pair, and the AC voltage module is used to provide a high-voltage AC voltage to the ultraviolet excitation electrode pair; In the ultraviolet lamp module with double ultraviolet light windows, the ultraviolet lamp body is a cylindrical glass tube. First, one ultraviolet lamp mounting opening of the cylindrical glass tube is bonded to the ultraviolet light window with low-temperature glass powder at high temperature to achieve a semi-open and semi-closed structure. Subsequently, low-temperature glass powder is added to the other ultraviolet lamp mounting opening of the cylindrical glass tube, and the above device is sealed in a low-pressure environment filled with the working gas. Then, it is heated to the working temperature of the low-temperature glass powder to paste it, achieving the sealing of the working gas and the bonding of the ultraviolet light window. Subsequently, it is cooled and connected to the atmosphere, and after installing the ultraviolet excitation electrode pair, the production of the ultraviolet lamp module with double windows is completed.

2. The photoionization sensor according to claim 1, characterized in that, The AC voltage module includes a high-voltage power supply module and a high-voltage power conversion module; The high-voltage power supply module is connected to the high-voltage power conversion module; The high-voltage power conversion module is connected to the ultraviolet excitation electrode pair, and the high-voltage power conversion module is used to supply electric energy to the ultraviolet excitation electrode pair; 3. The photoionization sensor according to claim 1, wherein The ultraviolet lamp module further includes a gas adsorbent; The gas adsorbent is contained in the ultraviolet lamp module, and the gas adsorbent is used to adsorb impurity gases in the ultraviolet lamp module; 4. The photoionization sensor according to any one of claims 1 to 3, characterized in that, The gas flow area includes an air inlet, an air outlet, and an ionization area; The air inlet is arranged on the sensor body, and the gas to be measured enters the ionization region through the air inlet, and the gas to be measured is ionized in the ionization region; The exhaust port is arranged on the sensor body, and the exhaust port is used to extract the gas to be measured from the ionization region.

5. The photoionization sensor according to claim 4, wherein The gas flow region further includes an air pump for pumping the gas to be measured into the ionization region.

6. The photoionization sensor according to claim 4, wherein The gas flow region further includes an exhaust pump for discharging the gas to be measured from the ionization region.

7. The photoionization sensor according to any one of claims 1 to 3, characterized in that The ion current receiving electrode pair is placed parallel to the ultraviolet light window.

8. The photoionization sensor according to any one of claims 1 to 3, characterized in that, The ion current receiving electrode pair is placed perpendicular to the ultraviolet light window.

9. The photoionization sensor according to any one of claims 1 to 3, characterized in that, The output module includes a logic judgment module and an information output module; The logic judgment module is connected to the amplifier circuit, and the logic judgment module is used to analyze the signal processed by the amplifier circuit; The logic judgment module is connected to the information output module, and the information output module is used to output the gas concentration information of the gas to be measured.

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