Excimer lamp, and UV irradiation method using excimer lamp

Abstract

To provide an excimer lamp capable of suppressing the increase in ozone concentration with a simple structure.SOLUTION: An excimer lamp 10 is provided in an ultraviolet irradiation device 100 including a housing 60. The excimer lamp 10 includes a tubular discharge pipe (discharge container) 20 formed of a dielectric material such as quartz glass, and has an outer electrode 40 disposed on an outer surface 20S of the discharge pipe 20. The outer electrode 40 is formed as an electrode made of nickel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an excimer lamp capable of generating ozone and an ultraviolet irradiation method using the excimer lamp. [Background technology]

[0002] In an excimer lamp, a discharge gas is sealed inside a discharge tube, and an electrode (inner electrode) is provided inside the discharge tube and an electrode (outer electrode) is provided on the outer surface of the discharge tube. Excimer light (ultraviolet rays) is emitted by applying a high-frequency voltage between the electrodes.

[0003] For example, when an excimer lamp is applied to an ozone generator, the excimer lamp is placed in a flow tube (see Patent Document 1). In this case, while a raw material gas containing oxygen flows through the flow tube, ozone is generated by emitting ultraviolet light having a peak wavelength (e.g., 172 nm) in a wavelength range capable of generating ozone. Furthermore, an excimer lamp can also be applied to an ultraviolet irradiation device that performs processing by irradiating an object to be irradiated with ultraviolet light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-198145 Summary of the Invention [Problem to be solved by the invention]

[0005] Ultraviolet irradiation devices using excimer lamps are used in a variety of environments, including industrial applications in factories, etc. Ultraviolet irradiation devices are not only designed and installed in advance to suit the industrial product in which they are incorporated, but also come in modular configurations that can be detachably attached to the ultraviolet treatment device and incorporated into the device as needed.

[0006] In an excimer lamp that emits ultraviolet light containing wavelengths that generate ozone, ozone is generated when oxygen-containing gas remains as an impurity gas or gets mixed in the housing in which the object to be irradiated is placed or in the flow pipe through which the irradiated fluid flows. Therefore, particularly in an airtight housing or a flow pipe with a low flow rate, the ozone concentration increases, which can oxidize and damage surrounding components.

[0007] The temperature of the object or fluid being irradiated with ultraviolet light depends on the processing configuration of the device, and the temperature of the outer surface of the discharge tube of the excimer lamp is also affected by the ambient temperature and cooling conditions. Such temperature changes in the discharge tube of the excimer lamp may result in a decrease in the efficiency of ultraviolet light irradiation.

[0008] On the other hand, temperature control of the discharge tube of an excimer lamp requires precise temperature measurement using a sensor and temperature and flow rate adjustment of the source gas to be irradiated with ultraviolet light. However, such temperature control of the discharge tube leads to the complication of the device. Furthermore, when the excimer lamp is incorporated into the device using a modular configuration, temperature control of the discharge tube is difficult.

[0009] Therefore, it is desired to provide an excimer lamp that can suppress an increase in ozone concentration with a simple configuration. [Means for solving the problem]

[0010] An excimer lamp according to one aspect of the present invention comprises a discharge vessel capable of emitting ultraviolet rays that generate ozone in an oxygen-containing fluid, electrodes provided on the outer surface of the discharge vessel, and nickel provided on the outer surface of the discharge vessel, and is capable of operating the lamp when the temperature of the outer surface of the discharge vessel reaches 80°C or higher. Here, "operating the lamp" means that the lamp can continue to operate without substantially changing the ozone concentration and other ozone generation conditions compared to when the outer surface of the discharge vessel is at a temperature lower than 80°C. This configuration allows the lamp to operate when the outer surface of the discharge vessel reaches a temperature of 80°C or higher, a concept that has previously been rejected by those skilled in the art of ultraviolet irradiation devices.

[0011] Nickel can be used as an electrode, or it can be provided as a separate component. When nickel is used as an electrode, it can be made of nickel with an oxide film formed on it. It can also be made of nickel wire or nickel plate tightly wrapped around the outer surface of the discharge vessel.

[0012] The arrangement of the discharge vessel varies depending on the configuration of the ultraviolet treatment device, etc., and the discharge vessel can be arranged inside a flow path pipe. For example, the discharge vessel can be arranged coaxially inside a flow path pipe through which a fluid flows from an inlet to an outlet, and the distance between the outer surface of the discharge vessel and the inner surface of the flow path pipe can be set to be equal to or less than the transmission distance at which the ultraviolet intensity ratio of the ultraviolet rays radiated from the outer surface of the discharge vessel is attenuated to 20%.

[0013] Another aspect of the present invention is an ultraviolet irradiation method in which a discharge gas that radiates ultraviolet light having a wavelength that generates ozone in an oxygen-containing fluid is sealed in a discharge vessel, electrodes are provided on the outer surface of the discharge vessel, nickel is provided on the outer surface of the discharge vessel as an electrode or separately from the electrode, and the lamp is lit.

[0014] There are various configurations for disposing the discharge vessel. For example, the discharge vessel can be disposed within the housing of the processing device so that the lamp lights up in an airtight state. Furthermore, the discharge vessel can be disposed coaxially with a flow tube through which the fluid flows from the inlet to the outlet, with the distance between the outer surface of the discharge vessel and the inner surface of the flow tube being within the range of 1 mm to 10 mm, and the flow rate of the fluid flowing through the flow tube can be set to 3 L / min or less. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide an excimer lamp that can suppress an increase in ozone concentration with a simple configuration. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view taken along the electrode width direction of an excimer lamp according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0017] The excimer lamp of this embodiment will be described below with reference to the drawings.

[0018] Fig. 1 is a schematic cross-sectional view of an excimer lamp taken along the electrode width direction, and Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1.

[0019] Here, the excimer lamp 10 is installed in an ultraviolet irradiation device 100 that includes a housing 60. During operation of the ultraviolet irradiation device 100, the excimer lamp 10 emits ultraviolet rays containing wavelengths capable of generating ozone from a raw material gas containing oxygen, and performs ultraviolet irradiation processing on an irradiated object, irradiated fluid, or the like (not shown).

[0020] The excimer lamp 10 is detachably mounted in a housing (flow path pipe) 60, within which the irradiated fluid flows from an inlet 60A to an outlet 60B. The housing 60 is a cylindrical flow path pipe with a circular cross section, and the excimer lamp 10 is coaxially disposed within the housing 60. In other words, the excimer lamp 10 is housed within the housing 60 so that the lamp axis C of the excimer lamp 10 is aligned with the axis of the housing 60, and is held by a holding member (not shown).

[0021] On the other hand, the housing 60 in which the excimer lamp 10 is disposed may be configured as an airtight container in which the irradiated fluid is not flowed and the inside of the housing 60 is maintained in an airtight state. That is, the inlet 60A and the outlet 60B may be closed, and the internal space within the housing 60 of the ultraviolet irradiation device 100 may be configured so as not to be spatially connected to the external space outside the housing 60.

[0022] In this case, the housing 60 functions as a jacket tube that houses the excimer lamp 10, and transmits ultraviolet light emitted from the excimer lamp 10 to perform ultraviolet light irradiation processing on an object to be irradiated, a fluid to be irradiated, or the like around the housing 60. The ultraviolet light may be irradiated through an ultraviolet light transmitting window provided in part of the housing 60.

[0023] The excimer lamp 10 includes a tubular discharge tube (discharge vessel) 20 made of a dielectric material such as quartz glass, and is configured here as a discharge tube with a circular cross section along the tube diameter (lamp diameter) direction. A rare gas such as xenon gas or a mixture of these gases is sealed in the discharge space S within the discharge tube 20 as a discharge gas.

[0024] A foil electrode 30 is disposed inside the discharge tube 20, extending in a strip shape along the tube axis (lamp axis) C. The foil electrode 30 is covered by a columnar dielectric 50 made of quartz glass or the like, and is buried within the dielectric 50 without being exposed to the discharge space S. In other words, the foil electrode 30 is sealed (adhered) to the dielectric 50. A power supply line (power supply rod) 70 is connected to the end of the foil electrode 30 along the lamp axis C, and is also connected to an externally installed power supply unit (not shown).

[0025] The foil electrode 30 is arranged coaxially with its center position in the width direction and thickness direction aligned with the center position of the dielectric 50. Furthermore, the dielectric 50 is arranged coaxially with the discharge tube 20. Therefore, the foil electrode 30 is arranged coaxially with the discharge tube 20 and symmetrically with respect to the lamp axis C. In FIG. 2, the width direction of the foil electrode 30 is defined as the Y direction, and the direction perpendicular thereto (thickness direction) is defined as the X direction.

[0026] The outer electrode 40 arranged on the outer surface 20S of the discharge tube 20 is configured by winding a conductive wire made of a conductive metal along the outer surface of the discharge tube 20, and is wound spirally along the lamp axis C and arranged at predetermined intervals.

[0027] The outer electrode 40 is provided with such a spiral electrode portion (hereinafter referred to as the spiral portion 42) as well as conductive members (hereinafter referred to as the cylindrical members) 45A, 45B that contact both ends of the spiral portion 42. Here, the cylindrical members 45A, 45B are configured by wrapping a strip-shaped conductive plate around the lamp axis C in a cylindrical shape to cover part of the outer surface 20S of the discharge tube 20.

[0028] 2, the foil electrode 30 has a substantially constant cross-sectional shape along the lamp axis C, and has a knife-edge shape that tapers from a flat portion of constant thickness toward both ends in the width direction. On the other hand, the dielectric 50 has a flat external shape.

[0029] Here, the excimer lamp 10 is configured as a small excimer lamp. For example, the axial length (light-emitting length) in which discharge occurs inside the discharge tube 20 can be set in the range of 20 mm to 400 mm. The outer diameter of the discharge tube 20 can be set in the range of 5 mm to 30 mm, preferably in the range of 8 mm to 25 mm.

[0030] The thickness of the discharge tube 20 can be set in the range of, for example, 0.8 mm to 1.5 mm, taking into consideration prevention of discharge tube deterioration due to excimer light and suppression of an increase in discharge start voltage.

[0031] The foil electrode 30 and the outer electrode 40 have polarities set to anode and cathode, respectively. High frequency (for example, in the range of several kHz to several tens of MHz) and high voltage (for example, in the range of several kV to several tens of kV) are supplied to the excimer lamp 10 via a power supply line 70. The application of the high frequency voltage causes a discharge, which radiates ultraviolet light (for example, ultraviolet light with a wavelength of 172 nm) that is excimer light.

[0032] As described above, while the irradiated fluid flows through the housing 60, it is treated with ultraviolet light by the ultraviolet light emitted from the excimer lamp 10. The irradiated fluid that has been treated with ultraviolet light flows out from the outlet 60B of the housing 60. The distance D between the inner surface 60S of the housing 60 and the outer surface 20S of the discharge tube 20 is determined in consideration of the effective irradiation of ultraviolet light onto the source gas flowing through the housing 60, the phosphor film formed on the inner surface 60S of the housing 60 as needed, and the object to be irradiated placed outside the housing 60.

[0033] Here, the distance D between the outer surface 20S of the discharge tube 20 and the inner surface 60S of the housing 60 is determined so as to be equal to or less than the transmission distance at which the ultraviolet intensity ratio of the ultraviolet rays emitted from the outer surface 20S of the discharge tube is attenuated to 20%.

[0034] For example, when irradiating ultraviolet light with a wavelength of 172 nm, which has a transmission distance of several mm until it is attenuated to 20%, the housing 60 that houses the discharge tube 20 is set to a size (radial length) such that the distance D from the discharge tube 20 is relatively short.

[0035] Due to this arrangement of the housing 60 and the excimer lamp 10, the temperature of the outer surface 20S of the discharge tube 20 is likely to reach a high temperature during lamp operation. In particular, if the excimer lamp 10 is arranged in a casing 100K so as to operate in a low flow rate state or in an airtight state, the outer surface 20S of the discharge tube 20 is likely to reach a high temperature. As a result, a situation arises in which the lamp continues to operate in an environment exceeding 80°C, rather than in a normal (standard) operating environment for the excimer lamp 10, i.e., an operating environment in which the lamp is operated so that the temperature of the outer surface 20S of the discharge tube 20 is lower than 80°C.

[0036] In this embodiment, the outer electrode 40 is made of nickel with an oxide film formed thereon. Specifically, a nickel wire with an oxide film formed thereon is wound around the outer surface 20S of the discharge tube 20 so as to be in close contact with the outer surface 20S.

[0037] The nickel constituting the outer electrode 40 functions as a catalyst for decomposing ozone at high temperatures, particularly at 80°C or higher. As a result, when the excimer lamp 10 is turned on and the outer surface 20S of the discharge tube 20 is at a temperature exceeding 80°C, the outer electrode 40 promotes the decomposition of ozone generated by ultraviolet irradiation, thereby suppressing an increase in ozone concentration. Therefore, even if oxygen-containing gas is mixed into the housing 60 and ozone is generated, the ozone concentration does not increase, and the ozone does not oxidize and damage surrounding components.

[0038] On the other hand, the catalytic function of nickel with an oxide film on it for decomposing ozone decreases when the temperature drops below 80° C., especially to around 50° C. Therefore, when the temperature of the outer surface 20 of the discharge tube 20 is lower than 80° C., it does not function as a catalyst for decomposing ozone very effectively.

[0039] By using nickel with an oxide film that has the above-mentioned properties regarding ozone decomposition as the outer electrode 40, it is possible to suppress an increase in ozone concentration when the lamp is turned on at a temperature of 80°C or higher.

[0040] In particular, it is possible to effectively suppress an increase in ozone concentration even in an operating environment where the flow rate of the raw material gas flowing inside the casing (flow path pipe) 60 is small and the distance D between the outer surface 20S of the discharge tube 20 and the casing 60 is relatively short. For example, it is possible to effectively suppress an increase in ozone concentration even in an operating situation where the distance D is set in the range of 1 mm to 10 mm and an axial flow fan or the like is operated so that the flow rate of the raw material gas is 3 L / min or less.

[0041] The outer electrode 40 may be made of a nickel plate on which an oxide film is formed, instead of a nickel wire on which an oxide film is formed. Furthermore, the outer electrode 40 is not limited to a spirally wound configuration, and may be made of a nickel wire or nickel plate that is in close contact with the outer surface 20 of the discharge tube 20, which effectively promotes ozone decomposition under high temperature conditions. Furthermore, the nickel wire or nickel plate may be directly disposed on the outer surface 20 of the discharge tube 20. Instead of being integrated with the excimer lamp 10, a nickel material may be disposed within the housing 60 so that the temperature is 80°C or higher.

[0042] In this embodiment, the outer electrode 40 provided on the outer surface 20S of the discharge tube 20 is configured as an electrode made of nickel. However, the outer electrode 40 may not be made of nickel, but may be made of a metal different from the outer electrode 40, such that nickel is provided on the outer surface 20S side of the discharge tube 20. Even with this configuration, an increase in ozone concentration can be suppressed. For example, the outer electrode 40 can be made of a metal such as stainless steel, and the cylindrical members 45A, 45B can be made of nickel with an oxide film formed thereon.

[0043] The excimer lamp 10, which is integrally made of nickel material, is detachably attached to the housing 60 of the ultraviolet irradiation device 100. This allows the excimer lamp 10 and the nickel material to be replaced at the same time. It is also possible to replace only the nickel material and then reattach the excimer lamp 10 to the housing 60.

[0044] It is possible to configure the inner electrode as an electrode other than the foil electrode 30. Furthermore, the discharge tube 20 may be used as a dielectric, and an electrode may be provided on the outer surface of the discharge tube 20 to apply a voltage. [Explanation of symbols]

[0045] 10 Excimer Lamp 20 Discharge tube (discharge vessel) 30 foil electrode 40 Outer electrode (electrode) 50 Dielectric 60 Housing (flow pipe, airtight container, jacket pipe) 100 Processing equipment

Claims

1. a discharge vessel capable of emitting ultraviolet light to generate ozone in an oxygen-containing fluid; an electrode provided on the outer surface side of the discharge vessel; nickel provided on the outer surface side of the discharge vessel, An excimer lamp capable of lighting when the temperature of the outer surface of the discharge vessel is 80°C or higher.

2. 2. The excimer lamp of claim 1, wherein the nickel is configured as the electrode.

3. 3. The excimer lamp according to claim 2, wherein the electrodes are made of nickel having an oxide film formed thereon.

4. 3. The excimer lamp according to claim 2, wherein the electrodes are made of nickel wire or nickel plate and are wound tightly around the outer surface of the discharge vessel.

5. 2. The excimer lamp according to claim 1, wherein the nickel is provided separately from the electrodes.

6. the discharge vessel is coaxially disposed within a flow pipe through which the fluid flows from an inlet to an outlet; 2. The excimer lamp according to claim 1, wherein the distance between the outer surface of the discharge vessel and the inner surface of the flow path tube is equal to or less than the transmission distance at which the ultraviolet intensity ratio of the ultraviolet light radiated from the outer surface of the discharge vessel is attenuated to 20%.

7. a discharge gas that emits ultraviolet light having a wavelength that generates ozone in an oxygen-containing fluid is sealed in a discharge vessel; An electrode is provided on the outer surface side of the discharge vessel, nickel is provided on the outer surface side of the discharge vessel as the electrode or separately from the electrode; 1. A method for irradiating ultraviolet light using an excimer lamp, characterized in that the lamp is turned on.

8. 9. The ultraviolet irradiation method using an excimer lamp according to claim 8, wherein the discharge vessel is disposed in a housing of a processing device so that the lamp lights up in an airtight state.

9. the discharge vessel is arranged coaxially with a flow path pipe through which the fluid flows from an inlet to an outlet, the distance between the outer surface of the discharge vessel and the inner surface of the flow path pipe being within a range of 1 mm to 10 mm; 8. The ultraviolet irradiation method using an excimer lamp according to claim 7, wherein the flow rate of the fluid flowing through the flow pipe is set to 3 L / min or less.

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