Ultraviolet irradiation device

Abstract

To provide an ultraviolet ray irradiation device that can suppress reduction in the uniformity ratio in the tube axial direction of a barrier discharge lamp.SOLUTION: An ultraviolet ray irradiation device according to an embodiment includes: a housing which has a box shape and one end of which is open; a barrier discharge lamp which is provided in the housing and can emit the ultraviolet ray; and an air flow formation part which makes purge gas flow toward the barrier discharge lamp in the housing. The barrier discharge lamp includes: a light-emitting tube which extends in one direction, has an annular shape and is enclosed with gas; an internal electrode which is provided in the light-emitting tube; and an external electrode which is provided on the outside of the light-emitting tube. The air flow formation part forms the flow of the purge gas flowing in the vicinity of the end of on the side opposed to the opening of the housing of the light-emitting tube.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments of the present invention relate to an ultraviolet irradiation device. [Background Art]

[0002] There is an ultraviolet irradiation device provided with a barrier discharge lamp that emits ultraviolet light. An ultraviolet irradiation device including a barrier discharge lamp is used, for example, for surface treatments such as removal of organic substances adhering to the surface of an object (photo-cleaning treatment), surface modification, and formation of oxide films. A barrier discharge lamp includes, for example, an internal electrode provided inside an arc tube and an external electrode provided outside the arc tube. When an AC voltage is applied between the internal electrode and the external electrode, dielectric barrier discharge occurs, and ultraviolet light having a specific wavelength is irradiated according to the type of gas sealed inside the arc tube.

[0003] Here, when performing treatment with ultraviolet light, gas may be released from an object. For example, when the surface of an object contains an organic substance, the organic substance may be decomposed by irradiation of ultraviolet light, and a gas containing components of the organic substance may be released. Further, when a volatile material is applied to the surface of an object, a gas containing components of the volatile material is released. When the released gas reaches the barrier discharge lamp, components contained in the gas may adhere to the surface of the barrier discharge lamp, thereby reducing the uniformity of the barrier discharge lamp in the tube axial direction. A decrease in uniformity tends to cause uneven treatment, which may lead to deterioration in the quality of the treated object.

[0004] Therefore, a technique has been proposed in which a barrier discharge lamp is provided inside a box-shaped housing having one open end, and the inside of the box-shaped housing is purged with nitrogen gas. If the barrier discharge lamp is provided in a space filled with nitrogen gas, even if gas is released from the object, it is possible to suppress the released gas from reaching the barrier discharge lamp.

[0005] However, if the processing time is long or the number of processes is large, the released gas may reach the barrier discharge lamp over time. Similarly, if the amount of gas released is large, the released gas may reach the barrier discharge lamp. Therefore, simply filling the area around the barrier discharge lamp with nitrogen gas may reduce the uniformity of the barrier discharge lamp in the axial direction of the tube.

[0006] Therefore, there was a need for the development of an ultraviolet irradiation device that could suppress the decrease in uniformity in the axial direction of a barrier discharge lamp. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2013-191758 [Overview of the project] [Problems that the invention aims to solve]

[0008] The problem that the present invention aims to solve is to provide an ultraviolet irradiation device that can suppress the decrease in uniformity in the axial direction of a barrier discharge lamp. [Means for solving the problem]

[0009] The ultraviolet irradiation device according to the embodiment comprises: a box-shaped housing with one end open; a barrier discharge lamp capable of irradiating ultraviolet light, provided inside the housing; and an airflow forming unit inside the housing that directs purge gas toward the barrier discharge lamp. The barrier discharge lamp has a discharge tube that extends in one direction, is annular in shape, and has gas sealed inside; an internal electrode provided inside the discharge tube; and an external electrode provided outside the discharge tube. The airflow forming unit forms the flow of the purge gas that flows near the end of the discharge tube on the side facing the opening of the housing. [Effects of the Invention]

[0010] According to embodiments of the present invention, it is possible to provide an ultraviolet irradiation device that can suppress a decrease in the uniformity of a barrier discharge lamp in the axial direction of the tube. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view illustrating an ultraviolet irradiation device according to this embodiment. [Figure 2] This is a schematic exploded view of the barrier discharge lamp, cooling unit, socket, and cover. [Figure 3] This is a schematic diagram illustrating a barrier discharge lamp. [Figure 4] Figure 3 is a schematic cross-sectional view of the barrier discharge lamp in the direction of line AA. [Figure 5] This is a schematic cross-sectional view illustrating an ultraviolet irradiation device related to a comparative example. [Figure 6] This is a schematic perspective view illustrating the airflow forming section. [Figure 7] This is a schematic perspective view illustrating an airflow forming section according to another embodiment. [Figure 8] Figure 5 is a table illustrating the effects of the ultraviolet irradiation device in the comparative example shown. [Figure 9] This table illustrates the effects of providing an airflow forming section. [Figure 10] This graph illustrates the change in homogeneity over time. [Modes for carrying out the invention]

[0012] The embodiments will be illustrated below with reference to the drawings. In each drawing, similar components are denoted by the same reference numerals, and detailed explanations are omitted as appropriate. Also, the arrows X, Y, and Z in each drawing represent three mutually orthogonal directions. For example, the direction perpendicular to the tube axis of the barrier discharge lamp 1 (discharge tube 11) is the X direction, the tube axis of the barrier discharge lamp 1 (discharge tube 11) is the Y direction, and the direction of ultraviolet irradiation is the Z direction.

[0013] Fig. 1 is a schematic cross-sectional view illustrating the ultraviolet irradiation device 100 according to the present embodiment. Although Fig. 1 illustrates the case where one barrier discharge lamp 1 is provided, the number of barrier discharge lamps 1 can be appropriately changed according to the application of the barrier discharge lamps 1, the size of the processing object 200, and the like. That is, it is sufficient that at least one barrier discharge lamp 1 is provided.

[0014] Further, as shown in Fig. 1, the ultraviolet irradiation device 100 (barrier discharge lamp 1) is provided on the upper side of the object 200 in the gravity direction. In this case, the object 200 may be moved relative to the ultraviolet irradiation device 100 (barrier discharge lamp 1). For example, the object 200 can be moved in a predetermined direction using a conveying device 201 such as a conveyor. The ultraviolet irradiation device 100 (barrier discharge lamp 1) may be moved relative to the object 200. For example, the object 200 can be placed on a mounting table or the like, and the ultraviolet irradiation device 100 (barrier discharge lamp 1) can be moved in a predetermined direction using a uniaxial robot or the like.

[0015] That is, it is only required that the relative position between the ultraviolet irradiation device 100 (barrier discharge lamp 1) and the object 200 can be changed. The position between the ultraviolet irradiation device 100 (barrier discharge lamp 1) and the object 200 may be constant. However, if the relative position between the ultraviolet irradiation device 100 (barrier discharge lamp 1) and the object 200 is changed, the irradiation area of the ultraviolet irradiation device 100 (barrier discharge lamp 1) can be reduced, so that the size reduction and energy saving of the ultraviolet irradiation device 100 (barrier discharge lamp 1) can be achieved.

[0016] As shown in Fig. 1, the ultraviolet irradiation device 100 includes, for example, a barrier discharge lamp 1, a cooling unit 2, a socket 3, a cover 4, a housing 5, and a purge gas supply unit 6. Fig. 2 is a schematic exploded view of the barrier discharge lamp 1, the cooling unit 2, the socket 3, and the cover 4. Fig. 3 is a schematic view illustrating the barrier discharge lamp 1. FIG. 4 is a schematic cross-sectional view of the barrier discharge lamp 1 in FIG. 3 along the line A-A. Note that in FIG. 4, the cooling unit 2 is also illustrated. As shown in FIG. 3 and FIG. 4, the barrier discharge lamp 1 includes, for example, an arc tube 11, an internal electrode 12, a reflective film 13, a holder 14, a lead wire 15, and an external electrode 16.

[0017] The arc tube 11 has a tubular shape, and has a form in which the overall length (the length in the tube axial direction) is longer than the tube diameter. The arc tube 11 extends in one direction (Y direction). The arc tube 11 can be, for example, a cylindrical tube. A sealing portion 11a is provided at each of both end portions of the arc tube 11 in the tube axial direction. By providing the sealing portion 11a, the internal space of the arc tube 11 can be hermetically sealed. The sealing portion 11a can be formed using, for example, a pinch sealing method or a shrink sealing method.

[0018] Furthermore, a conductive portion 11b and an outer lead 11c can be provided inside the sealing portion 11a. One conductive portion 11b can be provided for one sealing portion 11a. The planar shape of the conductive portion 11b is, for example, a quadrangle. The conductive portion 11b has a thin film shape. The conductive portion 11b can be formed of, for example, molybdenum foil.

[0019] The outer lead 11c has a linear shape, and can be provided at least on the sealing portion 11a on the side where the lead wire 15 is provided. One end of the outer lead 11c is electrically connected to the conductive portion 11b. The vicinity of the end portion of the outer lead 11c can be laser-welded or resistance-welded to the conductive portion 11b. The other end of the outer lead 11c can be exposed from the sealing portion 11a. The outer lead 11c contains, for example, molybdenum or the like.

[0020] The internal space of the discharge tube 11 is filled with gas. In the barrier discharge lamp 1, a barrier discharge is performed between the internal electrode 12 and the external electrode 16, supplying high-energy electrons to the filled gas and generating excimer-excited molecules. When the excimer-excited molecules return to their original state, light with a specific peak wavelength is generated depending on the type of gas. Therefore, the gas sealed in the internal space of the discharge tube 11 can be appropriately changed according to the application of the barrier discharge lamp 1. The gas sealed in the internal space of the discharge tube 11 can be, for example, a noble gas such as krypton, xenon, argon, or neon, or a mixed gas of several types of noble gases. The gas can also contain halogen gases as needed.

[0021] The gas pressure (sealing pressure) inside the discharge tube 11 at 25°C can be, for example, around 80kPa to 200kPa. The gas pressure (sealing pressure) inside the discharge tube 11 at 25°C can be determined using the standard conditions of the gas (SATP (Standard Ambient Temperature and Pressure): 25°C, 1 bar).

[0022] For example, when photocleaning the surface of a glass plate for a flat panel display, it is preferable to use xenon as the sealed gas. In this case, the sealing pressure of the xenon can be, for example, about 93 kPa. Using xenon as the sealed gas allows for the generation of ultraviolet light with a peak wavelength of 172 nm, thereby enhancing the cleaning effect.

[0023] The discharge tube 11 is formed from a material with high transmittance of ultraviolet light having a peak wavelength of 200 nm or less. For example, the discharge tube 11 can be formed from synthetic quartz glass.

[0024] The internal electrode 12 is located inside the discharge tube 11. The internal electrode 12 has, for example, a coil 12a and a leg 12b. The coil 12a and the leg 12b can be formed integrally. The coil 12a and the leg 12b are formed, for example, by plastic deformation of a wire. The wire diameter is, for example, about 0.2 mm to 1.0 mm. The wire material is, for example, tungsten, or doped tungsten, which is tungsten with potassium or the like added.

[0025] The coil 12a is spiral in shape and is located in the internal space of the discharge tube 11. The coil 12a extends along the tube axis of the discharge tube 11 through the central region of the internal space of the discharge tube 11. The pitch dimension P of the coil 12a can be, for example, about 10 mm to 120 mm.

[0026] Legs 12b are provided at each of the ends of the coil 12a. Legs 12b are linear in shape and extend from the ends of the coil 12a along the tube axis of the discharge tube 11. The ends of legs 12b are electrically connected to the conductive part 11b inside the sealing part 11a. The vicinity of the ends of legs 12b can be laser-welded or resistance-welded to the conductive part 11b.

[0027] The reflective film 13 can be provided between the external electrode 16 and the internal electrode 12 (coil 12a). For example, the reflective film 13 is in the form of a film and can be provided on the inner wall of the discharge tube 11. The reflective film 13 reflects ultraviolet light generated in the internal space of the discharge tube 11 that does not travel in the direction of irradiation toward the direction of irradiation. If the reflective film 13 is provided, the efficiency of ultraviolet light extraction can be improved. In addition, if the reflective film 13 is provided, the area of ​​the discharge tube 11 that is directly incident on by ultraviolet light can be reduced, thereby suppressing chemical structural changes of the discharge tube 11 caused by ultraviolet light.

[0028] The thickness of the reflective film 13 can be, for example, about 100 μm to 300 μm. The reflective film 13 contains, for example, SiO2. The reflective film 13 may also contain particles that scatter ultraviolet light. The particles that scatter ultraviolet light include, for example, aluminum oxide.

[0029] The reflective film 13 is not strictly necessary and can be omitted. However, if the reflective film 13 is provided, the efficiency of ultraviolet light extraction can be improved, and chemical structural changes of the discharge tube 11 due to ultraviolet light can be suppressed.

[0030] The holder 14 is provided at each of the ends of the discharge tube 11 in the axial direction of the tube. The holder 14 covers the ends of the discharge tube 11. The holder 14 can be formed from, for example, an insulating material. The holder 14 can be formed from, for example, steatite, aluminum oxide, etc. The holder 14 may be in contact with the external electrode 16 or may be spaced apart from the external electrode 16.

[0031] The lead wire 15 is electrically connected to the end of the outer lead 11c that is exposed from the sealing portion 11a. The lead wire 15 is electrically connected to the internal electrode 12 via the outer lead 11c and the conductive portion 11b. The lead wire 15 is electrically connected, for example, to a lighting circuit provided outside the ultraviolet irradiation device 100. Note that the lead wire 15 can be provided on only one end of the discharge tube 11, as shown in Figure 3, or on both ends of the discharge tube 11.

[0032] As shown in Figures 2 to 4, the external electrode 16 is provided outside the discharge tube 11. The external electrode 16 has, for example, an electrode body 16a and a plurality of mounting parts 16b. The electrode body 16a and the plurality of mounting parts 16b can be formed integrally.

[0033] The electrode body 16a extends along the outer surface of the discharge tube 11, in the direction of the tube axis of the discharge tube 11. The electrode body 16a is provided between the outer surface of the discharge tube 11 and the inner wall of the recess 2a of the cooling section 2. The electrode body 16a faces the internal electrode 12 (coil 12a). If a reflective film 13 is provided, the electrode body 16a can be provided in a position facing the reflective film 13.

[0034] The thickness of the electrode body 16a can be, for example, 0.1 mm or more and 1.0 mm or less. The electrode body 16a can be formed from a conductive material such as metal. For example, the electrode body 16a can be formed from stainless steel, aluminum, etc. Also, when the barrier discharge lamp 1 is lit, heat is generated along with ultraviolet light. Therefore, if the electrode body 16a contains a material with high thermal conductivity such as metal, the electrode body 16a can also be used as a heat dissipation part.

[0035] Multiple mounting portions 16b are provided on each of the ends of the electrode body 16a in a direction perpendicular to the tube axis direction of the discharge tube 11. One end of each of the multiple mounting portions 16b is provided on the end of the electrode body 16a. In a direction perpendicular to the tube axis direction of the discharge tube 11, the multiple mounting portions 16b extend away from the discharge tube 11.

[0036] Multiple mounting portions 16b are arranged in the direction of the tube axis of the discharge tube 11. Multiple mounting portions 16b are attached to the surface of the cooling unit 2 where the recess 2a opens. Multiple mounting portions 16b are attached to the cooling unit 2 using fastening members such as screws. The thickness and material of the multiple mounting portions 16b can be the same as that of the electrode body 16a.

[0037] By attaching multiple mounting parts 16b to the cooling part 2, deformation of the electrode body 16a due to the heat generated when the barrier discharge lamp 1 is lit can be suppressed. Suppressing deformation of the electrode body 16a suppresses changes in the distance between the internal electrode 12 (coil 12a) and the external electrode 16 (electrode body 16a), which would otherwise change the discharge state. Suppressing changes in the discharge state allows for higher uniformity. Therefore, the occurrence of processing irregularities can be suppressed.

[0038] Furthermore, multiple positioning members 16c can be provided. The positioning members 16c are plate-shaped and can be provided between the mounting portion 16b and the surface of the cooling portion 2 through which the recess 2a opens. For example, the number of positioning members 16c can be the same as the number of mounting portions 16b.

[0039] The positioning member 16c is attached to the cooling unit 2 together with the mounting part 16b using fastening members such as screws. Therefore, the positioning member 16c can be provided with holes that penetrate in the thickness direction. The thickness of the positioning member 16c can be, for example, about 0.3 mm. The material of the positioning member 16c can be, for example, a metal such as stainless steel.

[0040] When the positioning member 16c is attached to the cooling unit 2, a small gap may be provided between one end of the positioning member 16c and the electrode body 16a, and between the electrode body 16a and the outer surface of the discharge tube 11, or no gap may be provided. In this way, deformation of the electrode body 16a and the discharge tube 11 due to the heat generated when the barrier discharge lamp 1 is lit can be suppressed. Therefore, it is possible to suppress changes in the distance between the internal electrode 12 (coil 12a) and the external electrode 16 (electrode body 16a), which changes the discharge state, and to suppress changes in the cooling state due to gaps between the discharge tube 11 and the cooling unit 2. If changes in the discharge state and cooling state can be suppressed, the uniformity can be further increased. Therefore, the occurrence of processing irregularities can be further suppressed.

[0041] As shown in Figures 2 and 4, the cooling unit 2 faces the discharge tube 11 with the external electrode 16 in between. The cooling unit 2 extends in the direction of the tube axis of the barrier discharge lamp 1. The length of the cooling unit 2 in the direction of the tube axis can be, for example, the same as the length of the external electrode 16 (electrode body 16a) in the direction of the tube axis. At least one cooling unit 2 can be provided. If multiple cooling units 2 are provided, as shown in Figure 2, the multiple cooling units 2 can be arranged in a line in the direction of the tube axis of the barrier discharge lamp 1.

[0042] As shown in Figure 4, a recess 2a can be provided on one surface of the cooling section 2. The recess 2a extends in the direction of the tube axis of the discharge tube 11. Inside the recess 2a, the electrode body 16a of the external electrode 16 and the discharge tube 11 of the barrier discharge lamp 1 can be provided. At least a portion of the inner surface of the recess 2a can be in contact with the electrode body 16a.

[0043] The cooling section 2 is made of a material with high thermal conductivity. The cooling section 2 can be made of a metal such as aluminum or stainless steel. Also, as shown in Figure 4, a flow path 2b can be provided inside the cooling section 2. A refrigerant is supplied to the flow path 2b, for example, via an on-off valve 2c. The refrigerant is, for example, water. The refrigerant that has flowed through the flow path 2b is discharged to the outside of the cooling section 2. By flowing a refrigerant through the flow path 2b, the heat generated in the barrier discharge lamp 1 can be efficiently dissipated.

[0044] Socket 3 is electrically connected to, for example, a lighting circuit. The lead wires 15 and external electrodes 16 are electrically connected to socket 3 in a detachable manner. By electrically connecting the lead wires 15 and external electrodes 16 to socket 3, the internal electrodes 12 and external electrodes 16 can be electrically connected to a lighting circuit or the like.

[0045] The lighting circuit includes, for example, an inverter that converts power from an AC power source into high-voltage, high-frequency power (for example, a sine wave with a frequency of 37 kHz). For example, the lighting circuit lights up the barrier discharge lamp 1 with a lamp power of approximately 2.4 kW.

[0046] The cover 4 is box-shaped and houses the barrier discharge lamp 1, the cooling unit 2, and the socket 3 inside. One end of the cover 4 is open. If the cover 4 is provided, the purge gas G, described later, can be retained in the internal space of the cover 4. If the purge gas G is retained in the internal space of the cover 4, the barrier discharge lamp 1 can be protected.

[0047] The housing 5 is box-shaped and houses the barrier discharge lamp 1, cooling unit 2, socket 3, and cover 4 inside. One end of the housing 5 is open. The direction in which the opening of the housing 5 is provided can be the same as the direction in which the opening of the cover 4 is provided. As shown in Figure 1, ultraviolet light emitted from the barrier discharge lamp 1 is irradiated onto the object 200 through the opening of the cover 4 and the opening of the housing 5.

[0048] The purge gas G supplied from the purge gas supply unit 6 accumulates in the internal space of the housing 5. When the internal space of the housing 5 is filled with purge gas G, it is possible to suppress the gas 200a containing components of the object 200 released from the object 200 from reaching the barrier discharge lamp 1 (discharge tube 11).

[0049] Figure 5 is a schematic cross-sectional view illustrating an ultraviolet irradiation device 300 according to a comparative example. As shown in Figure 5, the ultraviolet irradiation device 300 includes a barrier discharge lamp 1, a cooling unit 2, a socket 3, a cover 4, a housing 5, and a purge gas supply unit 306. The purge gas supply unit 306 supplies purge gas G to the internal space of the housing 5, for example, via a flow rate control valve 306a. The purge gas G supplied to the internal space of the housing 5 remains in the internal space of the housing 5, and a portion of it is discharged to the outside through an opening in the housing 5.

[0050] If the purge gas G remains in the internal space of the housing 5, a layer 306b of the purge gas G is formed between the barrier discharge lamp 1 (discharge tube 11) and the object 200, as shown in Figure 5. If a layer 306b of the purge gas G is formed, it is possible to suppress the gas 200a released from the object 200 from reaching the barrier discharge lamp 1 (discharge tube 11). Therefore, it is possible to suppress the adhesion of components of the object 200 to the surface of the barrier discharge lamp 1 (discharge tube 11) and the decrease in the uniformity of the barrier discharge lamp 1 in the axial direction of the tube.

[0051] However, if the processing time is long or the number of items to be processed is large, gas 200a may reach the barrier discharge lamp 1 (discharge tube 11) over time. Also, if the amount of gas 200a released is large, gas 200a may reach the barrier discharge lamp 1 (discharge tube 11). When gas 200a reaches the barrier discharge lamp 1 (discharge tube 11), components of the object 200 may adhere to the surface of the barrier discharge lamp 1 (discharge tube 11), which may reduce the uniformity of the barrier discharge lamp 1 in the axial direction of the tube. A decrease in uniformity makes it easier for uneven processing to occur, which may reduce the quality of the processed object 200.

[0052] Therefore, the ultraviolet irradiation device 100 according to this embodiment is provided with a purge gas supply unit 6. As shown in Figure 1, the purge gas supply unit 6 includes, for example, a gas supply source 6a, an on-off valve 6b, a flow rate adjustment unit 6c, and an airflow forming unit 6d. The gas supply source 6a, the on-off valve 6b, and the flow rate adjustment unit 6c can be provided outside the housing 5. The airflow forming unit 6d can be provided in the internal space of the housing 5.

[0053] The gas supply source 6a supplies purge gas G to the airflow forming section 6d. The gas supply source 6a can be, for example, a high-pressure cylinder containing purge gas G or factory piping. The purge gas G is not particularly limited as long as it does not react easily with the target object 200 and the elements of the barrier discharge lamp 1. For example, the purge gas G can be nitrogen gas, argon, or a noble gas such as helium. In this case, if the purge gas G is a gas with a lower specific gravity than air (for example, helium), it becomes easier to retain the purge gas G in the internal space of the housing 5. Also, if the purge gas G is nitrogen gas, which is cheaper than a noble gas, running costs can be reduced.

[0054] The on-off valve 6b can be connected between the gas supply source 6a and the airflow forming unit 6d via piping or the like. The on-off valve 6b controls the supply and cessation of the supply of purge gas G. The on-off valve 6b can be, for example, a two-way valve.

[0055] The flow rate adjustment unit 6c can be connected between the on-off valve 6b and the airflow forming unit 6d via piping or the like. The flow rate adjustment unit 6c adjusts the flow rate of the purge gas G. The flow rate adjustment unit 6c can be, for example, a flow rate adjustment valve or a pressure adjustment valve. Furthermore, the flow rate adjustment unit 6c may also have the function of the on-off valve 6b.

[0056] The airflow forming unit 6d can be connected to the flow rate adjustment unit 6c, for example, via piping. Figure 6 is a schematic perspective view illustrating the airflow forming section 6d. As shown in Figures 1 and 6, the airflow forming section 6d can be installed alongside the barrier discharge lamp 1 (discharge tube 11) in a direction perpendicular to the tube axis direction (X direction). The airflow forming section 6d can be installed parallel to the barrier discharge lamp 1 (discharge tube 11). In the tube axis direction (Y direction) of the barrier discharge lamp 1 (discharge tube 11), the length of the airflow forming section 6d can be approximately the same as the length of the barrier discharge lamp 1.

[0057] As shown in Figure 6, the airflow forming section 6d can be provided with a purge gas G outlet 6d1. The outlet 6d1 can be, for example, a slit extending in the tube axis direction (Y direction) of the barrier discharge lamp 1 (discharge tube 11). Alternatively, multiple holes aligned in the tube axis direction (Y direction) of the barrier discharge lamp 1 (discharge tube 11) may be used as the outlet 6d1.

[0058] As shown in Figures 1 and 6, the purge gas G supplied to the airflow forming unit 6d is blown out from the outlet 6d1. The purge gas G blown out from the outlet 6d1 is supplied near the end of the discharge tube 11 on the object 200 side. That is, the airflow forming unit 6d flows the purge gas G towards the barrier discharge lamp 1 (discharge tube 11) inside the housing 5. In this case, as shown in Figure 1, the airflow forming unit 6d forms a flow of purge gas G that flows near the end of the discharge tube 11 on the side facing the opening of the housing 5 (the side facing the object 200). The purge gas G flows along the opening of the housing 5 from one side of the discharge tube 11 to the other side in a direction perpendicular to the direction in which the discharge tube 11 extends (X direction). If such a flow of purge gas G can be formed, the gas 200a moving from the object 200 towards the barrier discharge lamp 1 (discharge tube 11) can be carried away by the flow of purge gas G, moving it away from the barrier discharge lamp 1 (discharge tube 11).

[0059] The flow velocity and flow rate of the purge gas G discharged from the outlet 6d1 are not particularly limited, as long as the gas 200a is kept away from the barrier discharge lamp 1 (discharge tube 11). In this case, increasing the flow velocity or flow rate of the purge gas G will make it more difficult for the gas 200a to reach the barrier discharge lamp 1 (discharge tube 11). On the other hand, increasing the flow velocity or flow rate of the purge gas G will increase the running cost. Therefore, the flow velocity and flow rate of the purge gas G can be appropriately changed depending on the amount of gas 200a released, the distance between the barrier discharge lamp 1 (discharge tube 11) and the object 200, etc. The flow velocity and flow rate of the purge gas G can be appropriately determined by conducting experiments or simulations.

[0060] If an airflow forming section 6d is provided, it is possible to effectively suppress the adhesion of components of the object 200 to the surface of the barrier discharge lamp 1 (discharge tube 11). As a result, it is possible to suppress a decrease in the uniformity of the barrier discharge lamp 1 in the axial direction of the tube, and consequently, to suppress the occurrence of uneven processing.

[0061] Figure 7 is a schematic perspective view illustrating an airflow forming section 6da according to another embodiment. The airflow forming section 6da can be, for example, a blower fan. In this case, as shown in Figure 7, multiple airflow forming sections 6da can be arranged in the direction of the tube axis (Y direction) of the barrier discharge lamp 1 (discharge tube 11). The rows of multiple airflow forming sections 6da can be arranged parallel to the barrier discharge lamp 1 (discharge tube 11). The number of airflow forming sections 6da is not limited to the example given, and can be appropriately changed, for example, depending on the length of the tube axis of the barrier discharge lamp 1 (discharge tube 11). The airflow forming section 6da can also be a cross-flow fan (line flow fan®). When the airflow forming section 6da is a cross-flow fan, for example, one airflow forming section 6da can be provided that extends in the direction of the tube axis (Y direction) of the barrier discharge lamp 1 (discharge tube 11).

[0062] Furthermore, the airflow forming unit 6da supplies the purge gas G, which is accumulating in the internal space of the housing 5, to the vicinity of the end of the discharge tube 11 on the object 200 side. For this reason, the aforementioned flow rate adjustment unit 6c is connected to the internal space of the housing 5. The flow rate adjustment unit 6c supplies the purge gas G to the internal space of the housing 5 so that the purge gas G is present at least around the airflow forming unit 6da.

[0063] Even when an airflow forming section 6da is provided, a flow of purge gas G can be formed near the end of the discharge tube 11 on the object 200 side. Once a flow of purge gas G is formed, the gas 200a moving from the object 200 towards the barrier discharge lamp 1 (discharge tube 11) can be carried away by the flow of purge gas G, moving it away from the barrier discharge lamp 1 (discharge tube 11). In other words, by providing an airflow forming section 6da, the same effects as those of the airflow forming section 6d described above can be enjoyed.

[0064] Figure 8 is a table illustrating the effects of the ultraviolet irradiation device 300 according to the comparative example shown in Figure 5. Note that Figure 8 is a table illustrating the effects when the airflow forming section 6d (6da) is not provided. Figure 9 is a table illustrating the effects when the airflow forming section 6d (6da) is provided. In Figures 8 and 9, "0 mm" represents the center position of the barrier discharge lamp 1 (discharge tube 11) in the tube axis direction (Y direction). "300 mm", "600 mm", "700 mm", "-300 mm", "-600 mm", and "-700 mm" represent the distance from the center position. Figure 10 is a graph illustrating the change in uniformity over time.

[0065] As can be seen from Figures 8 and 9, if an airflow forming section 6d (6da) is provided, the variation in illuminance in the tube axis direction (Y direction) of the barrier discharge lamp 1 (discharge tube 11) can be reduced. In other words, uniformity can be improved. Furthermore, as can be seen from Figure 10, if an airflow forming section 6d (6da) is provided, the decrease in uniformity over time can be suppressed.

[0066] Furthermore, since the purge gas G is supplied directly to the vicinity of the barrier discharge lamp 1 (discharge tube 11), contact with outside air (air) to the barrier discharge lamp 1 (discharge tube 11) can be effectively suppressed. For example, when a barrier discharge occurs between the internal electrode 12 and the electrode body 16a, if there is ambient air in the gap between the electrode body 16a and the cooling unit 2, or in the gap between the electrode body 16a and the discharge tube 11, hydrogen nitrate gas may be generated. Also, moisture from the environment may condense on the surface of the electrode body 16a. When hydrogen nitrate gas dissolves in the condensed moisture, nitric acid is produced. When nitric acid comes into contact with the outer surface of the discharge tube 11, the transmittance of ultraviolet light decreases. If such chemical reactions occur repeatedly each time the barrier discharge lamp 1 is lit, the efficiency of ultraviolet light extraction may decrease over time.

[0067] If an airflow forming section 6d (6da) is provided, the purge gas G is supplied directly to the vicinity of the barrier discharge lamp 1 (discharge tube 11), so the generation of hydrogen nitrate gas and the condensation of moisture can be effectively suppressed. Therefore, the decrease in ultraviolet light extraction efficiency over time can be effectively suppressed.

[0068] Furthermore, if cover 4 is provided, the purge gas G supplied near the barrier discharge lamp 1 (discharge tube 11) can be retained, further suppressing the generation of hydrogen nitrate gas and the condensation of moisture. As a result, the decrease in ultraviolet light extraction efficiency over time can be further suppressed.

[0069] Although several embodiments of the present invention have been illustrated above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. Furthermore, the embodiments described above can be implemented in combination with each other. [Explanation of Symbols]

[0070] 1 Barrier discharge lamp, 2 Cooling unit, 5 Housing, 6 Purge gas supply unit, 6a Gas supply source, 6b On / off valve, 6c Flow rate adjustment unit, 6d Airflow forming unit, 11 Discharge tube, 12 Internal electrode, 16 External electrode, 16a Electrode body, 100 Ultraviolet irradiation device, 200 Target object, 200a Gas, G Purge gas

Claims

1. A box-shaped housing with one end open; A barrier discharge lamp that emits ultraviolet light is provided inside the aforementioned housing; Inside the housing, there is an airflow forming section that flows purge gas toward the barrier discharge lamp; It is equipped with, The aforementioned barrier discharge lamp is A light-emitting tube that extends in one direction, is tubular in shape, and has gas sealed inside; An internal electrode provided inside the light-emitting tube; An external electrode provided outside the aforementioned light-emitting tube; It has, The airflow forming unit is an ultraviolet irradiation device that forms the flow of the purge gas flowing near the end of the discharge tube on the side facing the opening of the housing.

2. The ultraviolet irradiation apparatus according to claim 1, wherein the purge gas is retained in the internal space of the housing.

3. The ultraviolet irradiation apparatus according to claim 1 or 2, wherein the purge gas flows along the opening of the housing from one side of the discharge tube to the other side in a direction perpendicular to the direction in which the discharge tube extends.

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