An electrodeless ultraviolet lamp, a method for adjusting luminous intensity, and a photoionization sensor.

Abstract

This invention provides an electrodeless ultraviolet lamp, a method for adjusting luminous intensity, and a photoionization sensor. The electrodeless ultraviolet lamp includes a glass outer shell and an ultraviolet window sealed at an opening in the glass shell to form a closed chamber inside. Multiple driving electrodes are fixedly sleeved on the glass shell and arranged at intervals along its axial direction. A driving module pre-stores a mapping relationship between the ultraviolet lamp's luminous intensity and the driving electrode pairs, used to determine the target driving electrode pair in response to an ultraviolet lamp luminous intensity control command, and apply an AC voltage of predetermined amplitude and frequency to the target driving electrode pair. The luminous intensity adjustment method is applied to the driving module and includes: in response to an ultraviolet lamp luminous intensity control command, determining the target driving electrode pair according to the mapping relationship between the ultraviolet lamp's luminous intensity and the driving electrode pairs; and applying an AC voltage of predetermined amplitude and frequency to the target driving electrode pair. The photoionization sensor includes the aforementioned electrodeless ultraviolet lamp. This invention solves the problem of the significant limitations of existing methods for adjusting the luminous intensity of ultraviolet lamps used in PID sensors.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ultraviolet lamp driving, and more particularly, to an electrodeless ultraviolet lamp with adjustable light intensity, a light intensity adjusting method of the electrodeless ultraviolet lamp, and a photo-ionization sensor comprising the electrodeless ultraviolet lamp. BACKGROUND

[0002] A photo-ionization sensor (PID) is usually used to detect volatile organic compounds (VOC) in the environment. Due to the diversity of the detection environment, sometimes it is necessary to detect VOC at an extremely low concentration of several ppb or even several ppb, and sometimes it is necessary to detect VOC at a high concentration of several thousand or even ten thousand ppm, which requires the range of the PID sensor to be large enough to cover a detection range of 7 orders of magnitude.

[0003] It is well known that the process of ionizing VOC molecules during the operation of a PID sensor is a dynamic two-way balance process, that is, while VOC molecules are ionized into VOC ions and electrons, some VOC ions and electrons recombine into VOC molecules. As the concentration of VOC increases, the number of VOC molecules ionized also increases, and the collision probability of VOC ions and electrons also increases. At this time, the ionization of VOC molecules and the concentration of VOC gas do not show a linear relationship, which is the main reason for the non-linear output of the PID sensor.

[0004] When the concentration of VOC increases, the recombination rate of VOC ions and electrons also increases. When the VOC reaches a certain concentration, a large number of VOC ions ionized will recombine with electrons before being collected by the ion detection electrode. At this time, 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, which is called the saturation phenomenon of the sensor. The saturation phenomenon is related to the light intensity of the vacuum ultraviolet lamp of the PID sensor, the structure of the ionization chamber, and the strength of the bias electric field.

[0005] In practical applications, for a PID sensor with a specific ionization chamber structure and bias electric field strength, if the saturation phenomenon of the PID sensor is to be improved or eliminated, the ionization of VOC molecules can be reduced by reducing the light intensity of the ultraviolet lamp. Specifically, the light intensity of the ultraviolet lamp is adjustable within a certain range, so that the PID sensor can meet the resolution requirement of ppb level at low concentration detection, and can also avoid the saturation phenomenon at high concentration detection.

[0006] The existing light intensity adjusting methods of the ultraviolet lamp for PID sensors mainly include the following two methods:

[0007] The first way is to adjust the amplitude of the driving voltage or adopt the pulse width modulation mode, to increase the light intensity of the ultraviolet lamp at low concentration detection, and to decrease the light intensity of the ultraviolet lamp at high concentration detection.

[0008] The second way is to adjust the light intensity of the ultraviolet lamp by modulating the frequency of the driving voltage, to improve the detection performance of the PID sensor.

[0009] However, although the above two ways can realize the adjustable light intensity of the ultraviolet lamp for the PID sensor within a certain range, both of the two ways need relatively complex driving circuits to cooperate, and when the driving voltage and the driving frequency decrease to a certain value, the ultraviolet lamp may not work normally due to the failure to meet the minimum excitation condition of the ultraviolet lamp. Each ultraviolet lamp has a specific threshold of voltage and frequency according to the type and pressure of the working medium filled therein, and when the corresponding threshold is met, the working medium is ionized and broken down. Therefore, the ways of adjusting the light intensity of the ultraviolet lamp by adjusting the amplitude or frequency of the driving voltage have certain limitations. SUMMARY

[0010] The present application aims to solve the problem of the great limitation of the light intensity adjustment mode of the existing ultraviolet lamp for the PID sensor.

[0011] In order to achieve the above-mentioned purpose, the present application provides an ultraviolet lamp with adjustable light intensity, a light intensity adjustment method of the ultraviolet lamp, and a photo-ionization sensor comprising the ultraviolet lamp.

[0012] According to a first aspect of the present application, an ultraviolet lamp with adjustable light intensity is provided, which comprises an ultraviolet lamp tube, a plurality of driving electrodes and a driving module.

[0013] The ultraviolet lamp tube comprises a glass shell with one end open, and an ultraviolet window sealingly arranged at the opening of the glass shell to form a closed chamber in the internal space of the glass shell.

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

[0015] The plurality of driving electrodes are fixedly sleeved on the glass shell and arranged along the axial direction of the glass shell, and each of the plurality of driving electrodes is electrically connected to the driving module.

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

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

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

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

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

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

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

[0023] Optionally, the driving electrodes are film electrodes formed on an outer wall of the glass envelope.

[0024] Alternatively, the driving electrodes are ring electrodes with a predetermined thickness.

[0025] According to a second aspect of the present application, there is provided a method for adjusting the luminous intensity of any of the above-described electrodeless ultraviolet lamps, which is applied to the driving module and specifically includes the following steps:

[0026] In response to an input ultraviolet lamp luminous intensity control instruction, a target pair of driving electrodes is determined according to a pre-acquired mapping relationship between ultraviolet lamp luminous intensity and pairs of driving electrodes.

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

[0028] Optionally, for the target pair of driving electrodes, 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 configured to be grounded and the high-voltage electrode is configured to be applied with a voltage.

[0029] According to a third aspect of the present application, there is provided a photoionization sensor, which includes any of the above-described electrodeless ultraviolet lamps.

[0030] The present application has the following advantages:

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

[0032] For the emission intensity adjustable electrodeless ultraviolet lamp of the present application, 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 positions of the ionized working gas corresponding to different driving electrode pairs to the UV 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 gas 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 gas is quenched is the same, but the distances from the photons to the UV window are different. In the process of the photons passing through the front working gas to reach the UV window, the photons collide with the working gas molecules constantly and are strongly absorbed, thereby causing the emission intensity of the electrodeless ultraviolet lamp to be different.

[0034] When the driving module applies a predetermined voltage to the two driving electrode pairs respectively, if the volumes of the ionized working gas corresponding to the two driving electrode pairs are different, the number of high-energy photons emitted when the plasma formed by the corresponding ionized working gas is quenched is different, and the distances from the photons to the UV window are also different, thereby causing the emission intensity of the electrodeless ultraviolet lamp to be different.

[0035] As can be seen from the above, for the emission intensity adjustable electrodeless ultraviolet lamp of the present application, the emission intensity of the electrodeless ultraviolet lamp can be adjusted by selecting different driving electrode pairs. In actual application, different emission intensity adjustment ranges can be obtained by adjusting the number of driving electrodes and / or the spacing between adjacent two driving electrodes. At the same time, when high concentration detection is performed, the driving electrode pair corresponding to the distance from the center position of the ionized working gas to the UV 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 small enough intensity, thereby effectively avoiding the situation that the ultraviolet lamp in the prior art cannot work due to insufficient driving voltage. As can be seen, the emission intensity adjustable electrodeless ultraviolet lamp of the present application can effectively solve the problem of large limitation of the emission intensity adjustment mode of the existing PID sensor ultraviolet lamp.

[0036] The light intensity adjusting method of the electrodeless ultraviolet lamp and the optical ionization sensor according to the present application belong to one general inventive concept with the electrodeless ultraviolet lamp with adjustable light intensity described above, and at least have the same beneficial effects as the electrodeless ultraviolet lamp with adjustable light intensity described above, which will not be repeated here.

[0037] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0038] The present application can be better understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals are used to indicate like parts, in all the figures.

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

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

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

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

[0043] In order to enable those skilled in the art to more fully understand the technical solutions of the present application, the following will be a more comprehensive and detailed description of the exemplary embodiments of the present application in conjunction with the accompanying drawings. Obviously, one or more embodiments of the present application described below are only one or more of the specific ways to implement the technical solutions of the present application, and are not exhaustive. It should be understood that other ways belonging to one general inventive concept can be used to implement the technical solutions of the present application, and should not be limited by the exemplary described embodiments. Based on one or more embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0044] Embodiment: Figure 1 A structural schematic diagram of the electrodeless ultraviolet lamp with adjustable light intensity according to an embodiment of the present application is shown, in which the driving electrode is shown in the form of a section, and the upper and lower parts constitute a complete driving electrode. Referring to Figure 1The electrodeless ultraviolet lamp with adjustable light intensity comprises an ultraviolet lamp tube 100, a plurality of driving electrodes 200 and a driving module 300.

[0045] The ultraviolet lamp tube 100 comprises a glass shell 110 with one end open, and an ultraviolet window 120 sealingly arranged at the opening of the glass shell 110 to form a closed chamber in the internal space of the glass shell 110.

[0046] The closed chamber is filled with working gas.

[0047] The plurality of driving electrodes 200 are fixedly sleeved on the glass shell 110 and arranged along the axial direction of the glass shell 110 at intervals, and 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 light intensity of the ultraviolet lamp and the driving electrode pairs, and is used for determining a target driving electrode pair in response to an input light intensity control instruction of the ultraviolet lamp, and applying an alternating voltage with a predetermined amplitude and frequency to the target driving electrode pair.

[0049] Specifically, in the embodiment of the present application, the working gas filled in the closed chamber is inert gas or an isotope of hydrogen; the ultraviolet window 120 is made of a crystal material, such as MgF2 or CaF2, each of which has a specific cutoff wavelength, for example, the cutoff wavelength of MgF2 crystal is about 117 nanometers, and the ultraviolet photon energy transmitted by the MgF2 crystal window is considered to be 10.6eV.

[0050] Further, in the embodiment of the present application, for the target driving electrode pair, one of the driving electrodes is a ground electrode and the other 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] Further, in the embodiment of the present application, the number of driving electrodes 200 is even.

[0052] The plurality of driving electrodes 200 are sequentially divided into a plurality of pairs of driving electrodes 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 A driving electrode configuration schematic diagram of the embodiment of the present application is shown. Referring to Figure 2In the embodiment of the present application, 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 and spacedly distributed on the glass envelope 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 form a driving electrode pair. The distance between the high-voltage electrode A1 and the ground electrode A2, the distance between the high-voltage electrode A3 and the ground electrode A4, and the distance between the high-voltage electrode A5 and the ground electrode A6 are equal. The distance between the ground electrode A2 and the high-voltage electrode A3 and the distance between the ground electrode A4 and the high-voltage electrode A5 are equal.

[0055] When 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 are respectively driven, the number of high-energy photons emitted when the plasma formed by the ionized working gas is quenched is the same, but the distance of the photons to the ultraviolet window is not the same. The photons collide with the working gas molecules in the process of passing through the front working gas to reach the ultraviolet window, and are strongly absorbed, thereby causing the luminous intensity of the electrodeless ultraviolet lamp to be different. Of course, it can be selected that for the above three driving electrode pairs, only one of the driving electrode pairs can be driven at the same time, any two of the driving electrode pairs can be driven at the same time, or all the three electrode pairs can be driven at the same time to meet the required ultraviolet light intensity for the PID sensor to work.

[0056] Further, as an optional embodiment, in the embodiment of the present application, one of the plurality of driving electrodes 200 is configured to be only a ground electrode and the remaining driving electrodes are all configured to be only high-voltage electrodes.

[0057] Specifically, Figure 3 Another driving electrode configuration schematic diagram of the embodiment of the present application is shown. Referring to Figure 3 In the embodiment of the present application, the high-voltage electrode B1, the ground electrode B2 and the high-voltage electrode B3 are sequentially and spacedly distributed on the glass envelope 110. When the high-voltage electrode B1 and the ground electrode B2 and the high-voltage electrode B3 and the ground electrode B2 are respectively driven, the number of high-energy photons emitted when the plasma formed by the ionized working gas in the corresponding part is quenched is not the same, and the distance of the photons to the ultraviolet window is also not the same, thereby causing the luminous intensity of the electrodeless ultraviolet lamp to be different.

[0058] Further, as an optional embodiment, in the embodiment of the present application, one of the plurality of driving electrodes 200 is configured to be only a high-voltage electrode and the remaining driving electrodes are all configured to be only ground electrodes.

[0059] Specifically, Figure 4 Another driving electrode configuration schematic diagram of the embodiment of the present application is shown. Referring toFigure 4 In the embodiment of the present application, the voltage electrode C1, the ground electrode C2 and the ground electrode C3 are distributed on the glass envelope 110 in sequence. 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 working gas in the corresponding part is quenched by the plasma formed by ionization is different, the distance of the photons to the ultraviolet window is also different, and thus the luminous intensity of the electrodeless ultraviolet lamp is different.

[0060] Further, in the embodiment of the present application, the driving electrode 200 is a film electrode formed on the outer wall of the glass envelope 110.

[0061] Alternatively, the driving electrode 200 is a ring electrode with a predetermined thickness.

[0062] Specifically, in the embodiment of the present application, the driving electrode 200 can be a film electrode or a ring electrode. Strictly speaking, the film electrode can also be considered as a kind of ring electrode, but the thickness is relatively thin and it is directly formed on the glass envelope 110.

[0063] Specifically, unlike the prior art which fixedly makes all or most of the working gas in the ultraviolet lamp tube form plasma and then emits light, the embodiment of the present application emits light by forming plasma in the predetermined segmented area of the ultraviolet lamp tube, and by reasonably setting the number, distribution position and spacing of adjacent electrodes of the driving electrode, the electrodeless ultraviolet lamp can emit ultraviolet light of multiple gears and different intensities, thereby meeting the needs of the PID sensor.

[0064] Correspondingly, on the basis of the luminous intensity adjustable electrodeless ultraviolet lamp of the embodiment of the present application, the embodiment of the present application also proposes a luminous intensity adjusting method of the electrodeless ultraviolet lamp, which is applied to a driving module and includes the following steps:

[0065] In response to the input ultraviolet lamp luminous intensity control instruction, a 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 with a predetermined amplitude and frequency is applied to the target driving electrode pair.

[0067] Correspondingly, on the basis of the luminous intensity adjustable electrodeless ultraviolet lamp of the embodiment of the present application, the embodiment of the present application also proposes a photoionization sensor, which includes the above-mentioned luminous intensity adjustable electrodeless ultraviolet lamp.

[0068] While one or more embodiments of the application have been described above, it should be understood that they have been presented by way of example only, and not limitation. Numerous changes to the embodiments can be made in addition to those described above without departing from the spirit and scope of the application. Accordingly, the scope of the application is defined only by the appended claims, rather than the description appearing in this overview.

Claims

1. An electrodeless ultraviolet lamp having an adjustable light intensity, characterized by The ultraviolet lamp comprises an ultraviolet lamp tube, at least three driving electrodes and a driving module. The ultraviolet lamp tube comprises a glass envelope with an open end, and an ultraviolet window sealingly arranged at the opening of the glass envelope to form a closed chamber in the internal space of the glass envelope. The closed chamber is filled with working gas. The driving electrodes are fixedly sleeved on the glass envelope and arranged along the axial direction of the glass envelope. The driving module pre-stores a mapping relationship between the ultraviolet lamp light intensity and the driving electrode pairs, and is configured to determine a target driving electrode pair in response to an input ultraviolet lamp light intensity control instruction, and apply an alternating voltage with a predetermined amplitude and frequency to the target driving electrode pair. For the target driving electrode pair, one of the driving electrodes is a ground electrode and the other is a high-voltage electrode, and the driving module is configured to ground the ground electrode and apply a potential to the high-voltage electrode. For the driving electrodes, one of the driving electrodes is configured to be only a high-voltage electrode and the remaining driving electrodes are configured to be only ground electrodes, or for the driving electrodes, one of the driving electrodes is configured to be only a ground electrode and the remaining driving electrodes are configured to be only high-voltage electrodes.

2. The intensity-adjustable electrodeless ultraviolet lamp according to claim 1, wherein The driving electrodes are film electrodes formed on the outer wall of the glass envelope. Alternatively, the driving electrodes are ring electrodes with a predetermined thickness.

3. The method of adjusting the luminous intensity of the electrodeless ultraviolet lamp according to claim 1 or 2, characterized in that, The driving module is applied to the ultraviolet lamp. The light intensity adjusting method comprises: In response to an input ultraviolet lamp light intensity control instruction, determining a target driving electrode pair according to a pre-acquired mapping relationship between the ultraviolet lamp light intensity and the driving electrode pairs. Applying an alternating voltage with a predetermined amplitude and frequency to the target driving electrode pair.

4. The method of adjusting the luminous intensity of an electrodeless ultraviolet lamp according to claim 3, characterized in that, For the target driving electrode pair, one of the driving electrodes is a ground electrode and the other is a high-voltage electrode, and the ground electrode is used for grounding and the high-voltage electrode is used for being applied with a potential.

5. A photoionization sensor characterized by, The ultraviolet lamp comprises the light intensity adjustable electrodeless ultraviolet lamp of claim 1 or 2.

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