Electrodeless ultraviolet lamp, luminous intensity adjusting method and photoionization sensor

Abstract

The invention provides an electrodeless ultraviolet lamp, a luminous intensity adjusting method and a photoionization sensor. According to the electrodeless ultraviolet lamp, an ultraviolet lamp tube comprises a glass shell and an ultraviolet window, wherein the ultraviolet window is arranged at an opening of the glass shell in a sealed mode so that a closed cavity can be formed in the ultraviolet lamp tube; the plurality of driving electrodes fixedly sleeve the glass shell and are arranged at intervals along the axial direction of the glass shell; a mapping relation between the luminous intensity of the ultraviolet lamp and the driving electrode pair is pre-stored in the driving module, and the driving module is used for responding to the control instruction of the luminous intensity of the ultraviolet lamp, determining a target driving electrode pair and applying alternating voltage with preset amplitude and frequency to the target driving electrode pair. The luminous intensity adjusting method is applied to the driving module and comprises the following steps: in response to an ultraviolet lamp luminous intensity control instruction, determining a target driving electrode pair according to a mapping relationship between the ultraviolet lamp luminous intensity and the driving electrode pair; and applying an AC voltage with a predetermined amplitude and frequency to the target driving electrode pair. The photoionization sensor comprises the electrodeless ultraviolet lamp. According to the ultraviolet lamp, the problem that the luminous intensity adjusting mode of an existing ultraviolet lamp for the PID sensor is large in limitation can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultraviolet lamp driving, and more specifically, relates to an electrodeless ultraviolet lamp with adjustable luminous intensity, a luminous intensity adjustment method of the electrodeless ultraviolet lamp, and a photoionization sensor including the electrodeless ultraviolet lamp. Background Art

[0002] Photoionization sensors (PID) are usually used to detect volatile organic compounds (VOCs) in the environment. Due to the diversity of the detection environment, sometimes it is necessary to detect extremely low concentrations of VOCs at the level of a dozen or a few ppb, and sometimes it is necessary to detect high concentrations of VOCs of several thousand or even more than 10,000 ppm. This requires that the PID sensor has a large enough range to achieve a detection range spanning 7 orders of magnitude.

[0003] As we all know, the process of ionizing VOC molecules when the PID sensor is working is a dynamic two-way equilibrium process, that is, while the VOC molecules are ionized into VOC ions and electrons, some VOC ions and electrons recombine into VOC molecules. As the VOC concentration continues to increase, the number of ionized VOC molecules also increases, and the probability of collision between VOC ions and electrons will also increase relatively. At this time, the ionization amount of VOC molecules is not linearly related to the VOC gas concentration, which is the main reason for the nonlinear output of the PID sensor.

[0004] As the concentration of VOC increases, the recombination rate of VOC ions and electrons also increases. When VOC reaches a certain concentration, a large number of ionized VOC ions recombine with electrons before being collected by the ion detection electrode. If the concentration of VOC continues to increase, the collected VOC ions will continue to decrease. At this time, the output signal of the PID sensor will no longer increase or even decrease. This is the so-called sensor saturation phenomenon. The occurrence of this saturation phenomenon is related to the luminous intensity of the vacuum ultraviolet lamp of the PID sensor, the structure of the ionization chamber, and the bias electric field strength.

[0005] In practical applications, for a PID sensor with a specific ionization chamber structure and bias electric field strength, if you want to improve or eliminate the saturation phenomenon of the PID sensor, you can reduce the ionization amount of VOC molecules by reducing the luminous intensity of the ultraviolet lamp. Specifically, the luminous intensity of the ultraviolet lamp is adjustable within a certain range, so that the PID sensor can meet the ppb-level resolution requirements for low-concentration detection, and will not be saturated when detecting high concentrations.

[0006] The existing PID sensor UV lamp luminous intensity adjustment methods mainly include the following two methods:

[0007] The first method is to increase the luminous intensity of the UV lamp by adjusting the amplitude of the driving voltage or using pulse width modulation to increase the amplitude of the driving voltage or the pulse width frequency during low concentration detection, and vice versa during high concentration detection.

[0008] The second method is to adjust the luminous intensity of the UV lamp by modulating the frequency of the driving voltage to improve the detection performance of the PID sensor.

[0009] However, although both of the above two methods can achieve adjustable luminous intensity of the ultraviolet lamp for PID sensor within a certain range, both methods require relatively complex driving circuits to cooperate, and when the driving voltage and driving frequency drop to a certain value, it is possible that the ultraviolet lamp cannot work normally due to failure to meet the minimum excitation conditions of the ultraviolet lamp. Each ultraviolet lamp has a specific voltage and frequency threshold value depending on the type and pressure of the working medium filled inside it. When the corresponding threshold value is met, the working medium is ionized and ionized continuously. It can be seen that the method of adjusting the luminous intensity of the ultraviolet lamp by adjusting the amplitude or frequency of the driving voltage has certain limitations. Summary of the invention

[0010] The purpose of the present invention is to solve the problem that the existing PID sensor ultraviolet lamp intensity adjustment method has great limitations.

[0011] In order to achieve the above-mentioned object, the present invention provides an electrodeless ultraviolet lamp with adjustable luminous intensity, a method for adjusting the luminous intensity of the electrodeless ultraviolet lamp, and a photoionization sensor including the electrodeless ultraviolet lamp.

[0012] According to a first aspect of the present invention, there is provided an electrodeless ultraviolet lamp with adjustable luminous intensity, the electrodeless ultraviolet lamp comprising an ultraviolet lamp tube, a plurality of driving electrodes and a driving module;

[0013] The ultraviolet lamp tube comprises a glass shell with an opening at one end, and an ultraviolet window sealed at the opening of the glass shell so that the inner space of the glass shell forms a closed chamber;

[0014] The closed chamber is filled with working gas;

[0015] The plurality of driving electrodes are all fixedly sleeved on the glass shell and arranged at intervals along the axial direction of the glass shell, and the plurality of driving electrodes are all electrically connected to the driving module;

[0016] The driving module pre-stores a mapping relationship between the ultraviolet lamp luminous intensity and the driving electrode pair, and is used to determine the target driving electrode pair in response to the input ultraviolet lamp luminous intensity control instruction, and apply an AC voltage of predetermined amplitude and frequency to the target driving electrode pair.

[0017] Optionally, for the target driving electrode pair, one of the driving electrodes is a ground electrode and the other of the driving electrodes is a high voltage electrode, and the driving module is used to ground the ground electrode and apply a potential to the high voltage electrode.

[0018] Optionally, for the multiple driving electrodes, one of the driving electrodes is configured to be used only as a high-voltage electrode and the remaining driving electrodes are configured to be used only as ground electrodes.

[0019] Optionally, for the multiple driving electrodes, one of the driving electrodes is configured to be used only as a ground electrode and the remaining driving electrodes are configured to be used only as high-voltage electrodes.

[0020] Optionally, the number of the driving electrodes is an even number;

[0021] The plurality of driving electrodes are sequentially divided into a plurality of pairs of driving electrodes along an arrangement direction;

[0022] For any pair of driving electrodes, one of the driving electrodes is configured to form a driving electrode pair only with the other driving electrode.

[0023] Optionally, the driving electrode is a membrane electrode formed on the outer wall of the glass housing;

[0024] Alternatively, the driving electrode is a ring-shaped electrode with a predetermined thickness.

[0025] According to a second aspect of the present invention, a method for adjusting the luminous intensity of any of the above-mentioned electrodeless ultraviolet lamps is provided. The method for adjusting the luminous intensity is applied to the driving module and specifically comprises the following steps:

[0026] In response to the input ultraviolet lamp luminous intensity control instruction, the target driving electrode pair is determined according to the pre-acquired mapping relationship between the ultraviolet lamp luminous intensity and the driving electrode pair;

[0027] An alternating voltage with a predetermined amplitude and frequency is applied to the target driving electrode pair.

[0028] Optionally, for the target driving electrode pair, one of the driving electrodes is a ground electrode and the other of the driving electrodes is a high-voltage electrode, the ground electrode is used for grounding, and the high-voltage electrode is used for applying a potential.

[0029] According to a third aspect of the present invention, there is provided a photoionization sensor, the photoionization sensor comprising any one of the above-mentioned electrodeless ultraviolet lamps.

[0030] The beneficial effects of the present invention are:

[0031] The electrodeless ultraviolet lamp with adjustable luminous intensity of the present invention has an ultraviolet window sealed at the opening of a glass shell to form a closed chamber for containing working gas inside, and a plurality of driving electrodes are fixedly sleeved on the glass shell, and the plurality of driving electrodes are arranged at intervals along the axial direction of the glass shell. A mapping relationship between the luminous intensity of the ultraviolet lamp and the driving electrode pair is pre-stored in the driving module, and is used to determine the target driving electrode pair in response to the input ultraviolet lamp luminous intensity control instruction, and apply an AC voltage of a predetermined amplitude and frequency to the target driving electrode pair.

[0032] For the electrodeless ultraviolet lamp with adjustable luminous intensity of the present invention, the positions of the ionized working gas corresponding to different driving electrode pairs in the closed chamber are different, that is, the distances from the center position of the ionized working gas corresponding to different driving electrode pairs to the ultraviolet window are different. At the same time, the volumes of the ionized working gas corresponding to different driving electrode pairs can be the same or different.

[0033] When the driving module applies a predetermined voltage to the two driving electrode pairs respectively, if the volumes of the ionized working gases corresponding to the two driving electrode pairs are the same, the number of high-energy photons emitted when the plasma formed by the corresponding ionized working gases is quenched is the same, but the distances for the photons to reach the ultraviolet window are different. In the process of passing through the working gas in front to reach the ultraviolet window, the photons continuously collide with the working gas molecules and will be strongly absorbed, thereby causing different luminous intensities of the electrodeless ultraviolet lamp.

[0034] When the driving module applies a predetermined voltage to the two driving electrode pairs respectively, if the volumes of the ionized working gases corresponding to the two driving electrode pairs are different, the numbers of high-energy photons emitted when the plasmas formed by the corresponding ionized working gases are quenched are different, and the distances for the photons to reach the ultraviolet window are also different, thereby causing the luminous intensity of the electrodeless ultraviolet lamp to be different.

[0035] According to the above, for the electrodeless ultraviolet lamp with adjustable luminous intensity of the present invention, the luminous intensity of the electrodeless ultraviolet lamp can be adjusted by selecting different driving electrode pairs. In actual application, different luminous intensity adjustment ranges can be obtained by adjusting the number of driving electrodes and / or the distance between two adjacent driving electrodes. At the same time, when performing high-concentration detection, a driving electrode pair with a closer distance from the center position of the corresponding ionized working gas to the ultraviolet window can be selected to reduce the volume requirement of the ionized working gas. In this case, even if the applied voltage is very small, the corresponding part of the working gas can be ionized so that the electrodeless ultraviolet lamp outputs ultraviolet light with a sufficiently small intensity, thereby effectively avoiding the situation in the prior art that the ultraviolet lamp cannot work due to insufficient driving voltage. It can be seen that the use of the electrodeless ultraviolet lamp with adjustable luminous intensity of the present invention can effectively solve the problem of large limitations in the luminous intensity adjustment method of the existing PID sensor ultraviolet lamp.

[0036] The luminous intensity adjustment method and photoionization sensor of the electrodeless ultraviolet lamp of the present invention belong to a general inventive concept with the above-mentioned electrodeless ultraviolet lamp with adjustable luminous intensity, and have at least the same beneficial effects as the above-mentioned electrodeless ultraviolet lamp with adjustable luminous intensity, and its beneficial effects are not repeated here.

[0037] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which the same or similar reference numerals are used throughout the drawings to represent the same or similar components.

[0039] Figure 1 A schematic structural diagram of an electrodeless ultraviolet lamp with adjustable luminous intensity according to an embodiment of the present invention is shown;

[0040] Figure 2 A schematic diagram of a driving electrode configuration according to an embodiment of the present invention is shown;

[0041] Figure 3 A schematic diagram of another driving electrode configuration according to an embodiment of the present invention is shown;

[0042] Figure 4 A schematic diagram of yet another driving electrode configuration according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to more fully understand the technical solution of the present invention, the exemplary embodiments of the present invention will be described in more comprehensive and detailed in conjunction with the accompanying drawings below. Obviously, the one or more embodiments of the present invention described below are only one or more of the specific ways in which the technical solution of the present invention can be implemented, and are not exhaustive. It should be understood that other ways belonging to a general inventive concept can be used to implement the technical solution of the present invention, and should not be limited by the exemplary embodiments described. Based on one or more embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work should fall within the scope of protection of the present invention.

[0044] Example: Figure 1 The schematic diagram of the structure of the electrodeless ultraviolet lamp with adjustable luminous intensity according to the embodiment of the present invention is shown, wherein the driving electrode is shown in the form of a cross section, and the two upper and lower opposite parts constitute a complete driving electrode. Figure 1The electrodeless ultraviolet lamp with adjustable luminous intensity according to the embodiment of the present invention comprises an ultraviolet lamp tube 100, a plurality of driving electrodes 200 and a driving module 300;

[0045] The ultraviolet lamp tube 100 includes a glass shell 110 with an opening at one end, and an ultraviolet window 120 sealed at the opening of the glass shell 110 so that the inner space of the glass shell 110 forms a closed chamber;

[0046] The closed chamber is filled with a working gas;

[0047] The plurality of driving electrodes 200 are fixedly mounted on the glass housing 110 and arranged at intervals along the axial direction of the glass housing 110 . The plurality of driving electrodes 200 are electrically connected to the driving module 300 .

[0048] The driving module 300 pre-stores a mapping relationship between the ultraviolet lamp luminous intensity and the driving electrode pair, and is used to determine the target driving electrode pair in response to the input ultraviolet lamp luminous intensity control instruction, and apply an AC voltage of predetermined amplitude and frequency to the target driving electrode pair.

[0049] Specifically, in the embodiment of the present invention, the working gas filled in the closed chamber is an inert gas or an isotope of hydrogen; the ultraviolet window 120 is made of a crystalline material, such as MgF2 or CaF2, each of which has a specific cutoff wavelength. For example, the cutoff wavelength of MgF2 crystal is around 117 nanometers. Usually, the energy of ultraviolet photons transmitted through the MgF2 crystal window is considered to be 10.6 eV.

[0050] Furthermore, in an embodiment of the present invention, for a target driving electrode pair, one driving electrode is a ground electrode and the other driving electrode is a high voltage electrode, and the driving module is used to ground the ground electrode and apply a potential to the high voltage electrode.

[0051] Furthermore, in the embodiment of the present invention, the number of the driving electrodes 200 is an even number;

[0052] The plurality of driving electrodes 200 are divided into a plurality of pairs of driving electrodes in sequence along the arrangement direction;

[0053] For any pair of driving electrodes, one of the driving electrodes is configured to form a driving electrode pair only with the other driving electrode.

[0054] Specifically, Figure 2 FIG. 1 is a schematic diagram showing a configuration of driving electrodes according to an embodiment of the present invention. Figure 2In the embodiment of the present invention, the high voltage electrode A1, the ground electrode A2, the high voltage electrode A3, the ground electrode A4, the high voltage electrode A5 and the ground electrode A6 are sequentially spaced and distributed on the glass housing 110. The high voltage electrode A1 and the ground electrode A2, the high voltage electrode A3 and the ground electrode A4, and the high voltage electrode A5 and the ground electrode A6 respectively constitute a driving electrode pair. Among them, the spacing between the high voltage electrode A1 and the ground electrode A2, the spacing between the high voltage electrode A3 and the ground electrode A4, and the spacing between the high voltage electrode A5 and the ground electrode A6 are all equal, and the spacing between the ground electrode A2 and the high voltage electrode A3 and the spacing between the ground electrode A4 and the high voltage electrode A5 are equal.

[0055] When driving high-voltage electrode A1 and ground electrode A2, high-voltage electrode A3 and ground electrode A4, and high-voltage electrode A5 and ground electrode A6 respectively, the number of high-energy photons emitted when the plasma formed by the ionized working gas is quenched is the same, but the distances for the photons to reach the ultraviolet window are different. In the process of the photons passing through the front working gas to reach the ultraviolet window, they constantly collide with the working gas molecules and will be strongly absorbed, which will cause different luminous intensities of the electrodeless ultraviolet lamp. Of course, it can be chosen that for the above three driving electrode pairs, only one of the driving electrode pairs can be driven at the same time, or any two driving electrode pairs can be driven at the same time, or all three electrode pairs can be driven at the same time to meet the ultraviolet light intensity required for the PID sensor to work.

[0056] Furthermore, as an optional implementation, in an embodiment of the present invention, for multiple driving electrodes 200, one of the driving electrodes is configured to only serve as a ground electrode and the remaining driving electrodes are configured to only serve as high-voltage electrodes.

[0057] Specifically, Figure 3 FIG. 2 shows another schematic diagram of a driving electrode configuration according to an embodiment of the present invention. Figure 3 In the embodiment of the present invention, the high voltage electrode B1, the ground electrode B2 and the high voltage electrode B3 are sequentially spaced and distributed on the glass housing 110. When the high voltage electrode B1 and the ground electrode B2 and the high voltage electrode B3 and the ground electrode B2 are driven respectively, the number of high energy photons emitted when the plasma formed by the ionization of the corresponding part of the working gas is quenched is different, and the distance of the photons to the ultraviolet window is also different, thereby making the luminous intensity of the electrodeless ultraviolet lamp different.

[0058] Furthermore, as an optional implementation, in an embodiment of the present invention, for multiple driving electrodes 200, one of the driving electrodes is configured to only serve as a high voltage electrode and the remaining driving electrodes are configured to only serve as ground electrodes.

[0059] Specifically, Figure 4 FIG. 2 shows another schematic diagram of a driving electrode configuration according to an embodiment of the present invention. Figure 4 In the embodiment of the present invention, the voltage electrode C1, the ground electrode C2 and the ground electrode C3 are sequentially spaced and distributed on the glass housing 110. When the voltage electrode C1 and the ground electrode C2 and the voltage electrode C1 and the ground electrode C3 are driven respectively, the number of high-energy photons emitted when the plasma formed by the ionization of the corresponding part of the working gas is quenched is different, and the distance of the photons to the ultraviolet window is also different, thereby making the luminous intensity of the electrodeless ultraviolet lamp different.

[0060] Furthermore, in the embodiment of the present invention, the driving electrode 200 is a membrane electrode formed on the outer wall of the glass housing 110;

[0061] Alternatively, the driving electrode 200 is a ring-shaped electrode having a predetermined thickness.

[0062] Specifically, in the embodiment of the present invention, the driving electrode 200 can be a membrane electrode or a ring electrode. Strictly speaking, the membrane electrode can also be considered as a kind of ring electrode, but it is thinner and is directly formed on the glass housing 110.

[0063] Specifically, different from the prior art method of fixedly making all or most of the working gases in the ultraviolet lamp tube form plasma and then emit light, the embodiment of the present invention makes the working gas in a predetermined segmented area of ​​the ultraviolet lamp tube form plasma and then emit light. By reasonably setting the number and distribution positions of the driving electrodes and the spacing between adjacent electrodes, the electrodeless ultraviolet lamp can emit ultraviolet light of multiple levels and different intensities, thereby meeting the needs of the PID sensor.

[0064] Accordingly, based on the electrodeless ultraviolet lamp with adjustable luminous intensity of the embodiment of the present invention, the embodiment of the present invention further proposes a luminous intensity adjustment method of the electrodeless ultraviolet lamp, and the luminous intensity adjustment method is applied to the driving module, comprising the following steps:

[0065] In response to the input ultraviolet lamp luminous intensity control instruction, the target driving electrode pair is determined according to the pre-acquired mapping relationship between the ultraviolet lamp luminous intensity and the driving electrode pair;

[0066] An alternating voltage of predetermined amplitude and frequency is applied to the target driving electrode pair.

[0067] Correspondingly, based on the electrodeless ultraviolet lamp with adjustable luminous intensity in the embodiment of the present invention, the embodiment of the present invention further proposes a photoionization sensor, which includes the above-mentioned electrodeless ultraviolet lamp with adjustable luminous intensity.

[0068] Although one or more embodiments of the present invention are described above, it should be known to those skilled in the art that the present invention can be implemented in any other form without departing from its subject matter and scope. Therefore, the embodiments described above are illustrative rather than restrictive, and many modifications and substitutions are obvious to those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. An electrodeless ultraviolet lamp with adjustable luminous intensity, characterized in that: It includes an ultraviolet lamp tube, a plurality of driving electrodes and a driving module; The ultraviolet lamp tube comprises a glass shell with an opening at one end, and an ultraviolet window sealed at the opening of the glass shell so that the inner space of the glass shell forms a closed chamber; The closed chamber is filled with working gas; The plurality of driving electrodes are all fixedly sleeved on the glass housing and arranged at intervals along the axial direction of the glass housing, and the plurality of driving electrodes are all electrically connected to the driving module; The driving module pre-stores a mapping relationship between the ultraviolet lamp luminous intensity and the driving electrode pair, and is used to determine the target driving electrode pair in response to the input ultraviolet lamp luminous intensity control instruction, and apply an AC voltage of predetermined amplitude and frequency to the target driving electrode pair.

2. The electrodeless ultraviolet lamp with adjustable luminous intensity according to claim 1, characterized in that: For the target driving electrode pair, one of the driving electrodes is a ground electrode and the other driving electrode is a high voltage electrode, and the driving module is used to ground the ground electrode and apply a potential to the high voltage electrode.

3. The electrodeless ultraviolet lamp with adjustable luminous intensity according to claim 2, characterized in that: For the plurality of driving electrodes, one of the driving electrodes is configured to be used only as a high voltage electrode and the remaining driving electrodes are configured to be used only as ground electrodes.

4. The electrodeless ultraviolet lamp with adjustable luminous intensity according to claim 2, characterized in that: For the plurality of driving electrodes, one of the driving electrodes is configured to be used only as a ground electrode and the remaining driving electrodes are configured to be used only as high-voltage electrodes.

5. The electrodeless ultraviolet lamp with adjustable luminous intensity according to claim 2, characterized in that: The number of the driving electrodes is an even number; The plurality of driving electrodes are sequentially divided into a plurality of pairs of driving electrodes along an arrangement direction; For any pair of driving electrodes, one of the driving electrodes is configured to form a driving electrode pair only with the other driving electrode.

6. The electrodeless ultraviolet lamp with adjustable luminous intensity according to claim 1, characterized in that: The driving electrode is a membrane electrode formed on the outer wall of the glass shell; Alternatively, the driving electrode is a ring-shaped electrode with a predetermined thickness.

7. The method for adjusting the luminous intensity of an electrodeless ultraviolet lamp according to any one of claims 1 to 6, characterized in that: Applied to the driving module; The luminous intensity adjustment method comprises: In response to the input ultraviolet lamp luminous intensity control instruction, the target driving electrode pair is determined according to the pre-acquired mapping relationship between the ultraviolet lamp luminous intensity and the driving electrode pair; An alternating voltage with a predetermined amplitude and frequency is applied to the target driving electrode pair.

8. The method for adjusting the luminous intensity of an electrodeless ultraviolet lamp according to claim 7, characterized in that: For the target driving electrode pair, one of the driving electrodes is a ground electrode and the other driving electrode is a high-voltage electrode. The ground electrode is used for grounding, and the high-voltage electrode is used for applying a potential.

9. A photoionization sensor, characterized in that: The electrodeless ultraviolet lamp with adjustable luminous intensity comprises the one described in any one of claims 1 to 6.

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