Ultraviolet ray irradiation apparatus

Abstract

To provide an ultraviolet ray irradiation apparatus capable of achieving miniaturization and appropriate purging with inert gas.SOLUTION: An ultraviolet ray irradiation apparatus according to an embodiment comprises: a cooling part having a recess extending in one direction; a cover provided on a side of the cooling part where the recess is open; and a barrier discharge lamp including a light-emitting tube disposed in a space defined by the recess of the cooling part and the cover and extending in the extending direction of the recess, and irradiating ultraviolet rays. In a direction orthogonal to the extending direction of the light-emitting tube, a surface of the cover facing the light-emitting tube is formed as a curved surface protruding away from the light-emitting tube. An inert gas is supplied into the space defined by the recess of the cooling part and the cover.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to an ultraviolet irradiation device. [Background technology]

[0002] There is an ultraviolet irradiation device equipped with a barrier discharge lamp that irradiates ultraviolet rays. An ultraviolet irradiation device equipped with a barrier discharge lamp is used, for example, for surface treatments such as removing organic matter adhering to the surface of an object (photo-cleaning treatment), surface modification, and oxide film formation. A barrier discharge lamp has, for example, an internal electrode provided inside the 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, a dielectric barrier discharge is generated, and ultraviolet rays having a specific wavelength depending on the type of gas sealed inside the arc tube are irradiated.

[0003] As mentioned above, the external electrode of a barrier discharge lamp is provided outside the arc tube. In this case, the external electrode is provided so as to be in contact with the arc tube. However, a gap may occur between the external electrode and the arc tube. If a gap exists between the external electrode and the arc tube, an aerial discharge may occur in the gap, and nitrogen oxides may be generated from the air (a mixture of nitrogen and oxygen) in the gap. When nitrogen oxides are generated, they may react with moisture in the atmosphere to generate nitrates. When nitrates are generated, they may adhere to the surface of an object or accumulate in the gap, which may damage the arc tube.

[0004] For this reason, a technique has been proposed in which a barrier discharge lamp is housed inside a vessel, and the vessel is filled with an inert gas such as nitrogen gas.

[0005] However, simply storing a barrier discharge lamp inside a container leads to new problems, such as an increase in the size of the ultraviolet irradiation device and an increase in the amount of inert gas consumed.Furthermore, there are areas in the corners of the container where the inert gas has difficulty flowing, which increases the time required to replace the air inside the container with the inert gas. Therefore, there has been a demand for the development of an ultraviolet irradiation device that can be made smaller and that can optimize purging with an inert gas. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-72645 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide an ultraviolet irradiation device that can be made compact and that can optimize purging with an inert gas. [Means for solving the problem]

[0008] An ultraviolet irradiation device according to an embodiment includes a cooling unit having a recess extending in one direction; a cover provided on the side of the cooling unit where the recess opens; and a barrier discharge lamp that is provided in a space defined by the recess of the cooling unit and the cover, has an arc tube extending in the direction of extension of the recess, and irradiates ultraviolet light. In a direction perpendicular to the direction in which the arc tube extends, the surface of the cover facing the arc tube is a curved surface that protrudes in a direction away from the arc tube. An inert gas is supplied to the space defined by the recess of the cooling unit and the cover. [Effects of the Invention]

[0009] According to an embodiment of the present invention, it is possible to provide an ultraviolet irradiation device that can be made smaller and that can optimize purging with an inert gas. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic side view illustrating an ultraviolet irradiation device according to an embodiment of the present invention; [Figure 2]2 is a cross-sectional view of the ultraviolet irradiation device shown in FIG. 1 taken along the line AA. [Figure 3] FIG. 1 is a schematic diagram illustrating a barrier discharge lamp. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be illustrated with reference to the drawings. In the drawings, like components are designated by like reference numerals and detailed descriptions thereof will be omitted where appropriate.

[0012] FIG. 1 is a schematic side view illustrating an ultraviolet irradiation device 100 according to the present embodiment. FIG. 2 is a cross-sectional view of the ultraviolet irradiation device 100 shown in FIG. 1 taken along the line AA. As shown in FIGS. 1 and 2, the ultraviolet irradiation device 100 includes, for example, a barrier discharge lamp 1, a cooling unit 2, a socket 3, a sealing unit 4, and a cover 5.

[0013] The barrier discharge lamp 1 is provided in a space defined by the recess 2 a of the cooling part 2 and the cover 5 . FIG. 3 is a schematic diagram illustrating the barrier discharge lamp 1. As shown in FIG. As shown in FIG. 3, the barrier discharge lamp 1 includes, for example, an arc tube 11, an internal electrode 12, a reflective film 13, a holder 14, lead wires 15, and an external electrode 16.

[0014] The arc tube 11 is tubular and has a configuration in which the overall length (length in the tube axis direction) is longer than the tube diameter. The arc tube 11 extends in one direction (for example, the direction in which the recess 2a of the cooling section 2 extends). The arc tube 11 is, for example, a cylindrical tube. Sealing sections 11a are provided on both ends of the arc tube 11 in the tube axis direction. By providing the sealing sections 11a, the internal space of the arc tube 11 is airtightly sealed. The sealing sections 11a are formed using, for example, a pinch seal method or a shrink seal method.

[0015] Furthermore, a conductive portion 11b and an outer lead 11c can be provided inside the sealing portion 11a. For example, one conductive portion 11b can be provided for each sealing portion 11a. The planar shape of the conductive portion 11b is, for example, a rectangle. The conductive portion 11b has a thin film shape. The conductive portion 11b is formed from, for example, molybdenum foil.

[0016] The outer lead 11c is linear 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 of the outer lead 11c is laser welded or resistance welded to the conductive portion 11b. The other end of the outer lead 11c is exposed from the sealing portion 11a. The outer lead 11c is a linear body containing, for example, molybdenum.

[0017] Gas is sealed in the internal space of the arc tube 11. In the barrier discharge lamp 1, a barrier discharge is generated between the internal electrode 12 and the external electrode 16, and high-energy electrons are given to the sealed gas to generate excited excimer molecules. When the excited excimer molecules return to their original state, ultraviolet light with a specific dominant wavelength is generated depending on the type of gas.

[0018] Therefore, the gas sealed in the internal space of the arc tube 11 can be changed as appropriate depending on the application of the barrier discharge lamp 1. The gas sealed in the internal space of the arc tube 11 can be, for example, a rare gas such as krypton, xenon, argon, or neon, or a mixed gas of multiple types of rare gases. The gas can also further contain a halogen gas or the like, as necessary.

[0019] The gas pressure (filled pressure) in the internal space of arc tube 11 at 25°C can be, for example, about 80 kPa to 200 kPa. The gas pressure (filled pressure) in the internal space of arc tube 11 at 25°C can be determined from the standard ambient temperature and pressure (SATP: temperature 25°C, 1 bar).

[0020] Here, when short-wavelength ultraviolet light (deep ultraviolet light) is irradiated onto organic matter, the bonds of the organic matter can be dissociated. Furthermore, when ultraviolet light with a dominant wavelength of 242 nm or less is irradiated onto an atmosphere containing oxygen (e.g., air), ozone and active oxygen are generated. Ozone and active oxygen have the ability to decompose organic matter. Therefore, when short-wavelength ultraviolet light is irradiated onto organic matter adhering to the surface of an object, the organic matter can be easily removed.

[0021] In this case, if the barrier discharge lamp 1 (xenon excimer lamp) is filled with xenon gas, it can irradiate ultraviolet light with a dominant wavelength of 172 nm. Therefore, if the barrier discharge lamp 1 is filled with xenon gas, it can increase the irradiation energy and also increase the ability to generate ozone and active oxygen. Therefore, for example, the barrier discharge lamp 1 filled with xenon gas is suitable for optically cleaning the surface of glass plates for flat panel displays.

[0022] The arc tube 11 is made of, for example, a material that has a high transmittance for ultraviolet light with a dominant wavelength of 200 nm or less. For example, the arc tube 11 can be made of synthetic quartz glass.

[0023] The internal electrode 12 is provided inside the arc tube 11. The internal electrode 12 has, for example, a coil 12a and legs 12b. The coil 12a and legs 12b can be formed integrally. The coil 12a and legs 12b are formed, for example, by plastically working 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 obtained by adding potassium or the like to tungsten.

[0024] The coil 12a has a spiral shape and is provided in the internal space of the arc tube 11. The coil 12a extends along the tube axis of the arc tube 11 in the central region of the internal space of the arc tube 11.

[0025] The legs 12b are provided at both ends of the coil 12a. The legs 12b are linear and extend from the ends of the coil 12a along the tube axis of the arc tube 11. The ends of the legs 12b are electrically connected to the conductive part 11b inside the sealing part 11a. The vicinity of the ends of the legs 12b can be laser-welded or resistance-welded to the conductive part 11b.

[0026] 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 arc tube 11. The reflective film 13 reflects ultraviolet rays that are generated in the internal space of the arc tube 11 and do not travel in the irradiation direction toward the irradiation direction. If the reflective film 13 is provided, the efficiency of extracting ultraviolet rays can be improved. Furthermore, if the reflective film 13 is provided, the area of the arc tube 11 onto which ultraviolet rays directly enter can be reduced, thereby suppressing chemical structural changes in the arc tube 11 caused by ultraviolet rays.

[0027] 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 can also contain particles that scatter ultraviolet light. The particles that scatter ultraviolet light include, for example, aluminum oxide.

[0028] The reflective film 13 is not necessarily required and can be omitted, but if the reflective film 13 is provided, the efficiency of extracting ultraviolet light can be improved and chemical structural changes in the arc tube 11 due to ultraviolet light can be suppressed.

[0029] The holder 14 is provided at each of both end portions of the arc tube 11 in the tube axis direction. The holder 14 covers the end portions of the arc tube 11. The holder 14 is made of, for example, an insulating material. The holder 14 can be made of, for example, steatite, aluminum oxide, or the like. The holder 14 may be in contact with the external electrode 16 or may be spaced apart from the external electrode 16.

[0030] The lead wire 15 is electrically connected to the end of the outer lead 11c 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 to, for example, a lighting circuit provided outside the ultraviolet irradiation device 100. Note that the lead wire 15 can be provided at only one end of the arc tube 11, as shown in FIG. 3, or at both ends of the arc tube 11.

[0031] As shown in FIGS. 2 and 3, the external electrode 16 is provided on the outside of the arc tube 11. The external electrode 16 extends in the axial direction of the arc tube 11 along the outer surface of the arc tube 11. The external electrode 16 is provided between the outer surface of the arc tube 11 and the inner wall of the recess 2a of the cooling section 2. The external electrode 16 faces the internal electrode 12 (coil 12a). When a reflective film 13 is provided, the external electrode 16 can be provided in a position facing the reflective film 13.

[0032] The thickness of the external electrode 16 is, for example, 0.1 mm or more and 1.0 mm or less. The external electrode 16 can be made of a conductive material such as metal. The external electrode 16 is made of, for example, stainless steel or aluminum. Furthermore, when the barrier discharge lamp 1 is turned on, heat is generated along with ultraviolet rays. Therefore, if the external electrode 16 contains a material with high thermal conductivity such as metal, the external electrode 16 can also be used as a heat dissipation section.

[0033] 1 and 2, the cooling part 2 faces the arc tube 11 across the external electrode 16. The cooling part 2 extends in the tube axis direction of the barrier discharge lamp 1. The length of the cooling part 2 in the tube axis direction can be, for example, the same as or longer than the length of the external electrode 16 in the tube axis direction.

[0034] 2, a recess 2a can be provided on one surface of the cooling part 2. The recess 2a extends in the tube axis direction of the arc tube 11. For example, an external electrode 16 and the arc tube 11 of the barrier discharge lamp 1 can be provided inside the recess 2a.

[0035] In this case, a gap is provided between the inner wall of the recess 2a and the external electrode 16. The center of the circle of curvature of the inner wall of the recess 2a can be aligned with the central axis of the arc tube 11, for example. In this way, the dimension between the inner wall of the recess 2a and the external electrode 16 can be made approximately uniform in the direction perpendicular to the extension direction of the arc tube 11.

[0036] The cooling unit 2 is made of a material with high thermal conductivity. The cooling unit 2 can be made of a metal such as aluminum or stainless steel. As shown in FIG. 2, a flow path 2b can be provided inside the cooling unit 2. The flow path 2b extends in the same direction as the cooling unit 2. A pair of pipe joints 2c can be connected to the flow path 2b, for example. A refrigerant supplied to the flow path 2b from one pipe joint 2c flows inside the flow path 2b and is discharged to the outside of the cooling unit 2 from the other pipe joint 2c. The refrigerant is, for example, water. By flowing the refrigerant inside the flow path 2b, the heat generated in the barrier discharge lamp 1 can be dissipated efficiently.

[0037] The socket 3 detachably holds the barrier discharge lamp 1. The lead wires 15 and external electrodes 16 of the barrier discharge lamp 1 are electrically connected via the socket 3 to a lighting circuit or the like provided outside the ultraviolet irradiation device 100. The lighting circuit has, 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 the barrier discharge lamp 1 with a lamp power of about 2.4 kW.

[0038] The sealing portion 4 airtightly seals the space defined by the cooling portion 2 and the cover 5. The sealing portion 4 also detachably holds the socket 3. The sealing portion 4 is provided at each of the ends on both sides of the cooling portion 2 and the cover 5.

[0039] The cover 5 is provided on the side of the cooling part 2 where the recess 2a is open. The cover 5 extends in the tube axis direction of the barrier discharge lamp 1. The cover 5 faces the arc tube 11 of the barrier discharge lamp 1 and the cooling part 2. The ultraviolet rays irradiated from the barrier discharge lamp 1 are emitted to the outside of the ultraviolet irradiation device 100 via the cover 5. For this reason, the cover 5 is made of, for example, a material that has a high transmittance for ultraviolet rays with a dominant wavelength of 200 nm or less. For example, the cover 5 can be made of synthetic quartz glass.

[0040] The end of cover 5 on the cooling unit 2 side is provided airtightly to the end where recess 2a of cooling unit 2 opens, via seal member 5a. The end of cover 5 on the sealing unit 4 side is provided airtightly to sealing unit 4 via seal member 5b.

[0041] In a direction perpendicular to the direction in which the arc tube 11 extends, the surface of the cover 5 facing the arc tube 11 is a curved surface that protrudes in a direction away from the arc tube 11. The center of the circle of curvature of the surface of the cover 5 facing the arc tube 11 can be aligned with the central axis of the arc tube 11, for example. For example, the cover 5 can be shaped as a part of a cylinder. In this case, the central axis of the cylinder can be aligned with the central axis of the arc tube 11, for example. In this way, the dimension between the arc tube 11 and the cover 5 can be made substantially uniform in the direction perpendicular to the direction in which the arc tube 11 extends.

[0042] The space 5c between the arc tube 11 and the cover 5 is connected to the space between the inner wall of the recess 2a and the external electrode 16. A piping joint 2e is connected to the hole 2d of the cooling section 2. In the direction in which the cooling section 2 extends, the inert gas is supplied from the piping joint 2e provided on one end side of the cooling section 2 to the hole 2d of the cooling section 2, and flows into the space between the inner wall of the recess 2a and the external electrode 16, and into the space 5c between the arc tube 11 and the cover 5. The inert gas that has flowed into these spaces is discharged to the outside of the cooling section 2 from the piping joint 2e provided on the other end side of the cooling section 2.

[0043] That is, the inert gas is supplied to the space defined by the recess 2a of the cooling unit 2 and the cover 5. The supply of the inert gas may be continuous or intermittent. The inert gas may also be supplied as needed. However, if the inert gas is supplied continuously, the reliability of the ultraviolet irradiation device 100 can be improved and the maintenance cycle can be extended.

[0044] Here, an aerial discharge may occur in the gap between external electrode 16 and arc tube 11. In this case, if air (a mixture of nitrogen and oxygen) is present in the gap, nitrogen oxides may be generated. Furthermore, if moisture is present in the atmosphere in the gap, the nitrogen oxides may react with the moisture to generate nitrates. If nitrates are generated, they may adhere to the inner surface of cover 5, hindering irradiation of ultraviolet rays, or may accumulate in the gap between external electrode 16 and arc tube 11, causing damage to arc tube 11.

[0045] Therefore, it is preferable that the inert gas supplied to the space between the inner wall of the recess 2a and the external electrode 16, and to the space 5c between the arc tube 11 and the cover 5, be a gas that does not contain oxygen. For example, the inert gas may be nitrogen gas or a rare gas.

[0046] In this case, the barrier discharge lamp 1, the cooling unit 2, and the socket 3 can be housed inside the container, and the container can be filled with inert gas. However, this requires a container with a large volume, which leads to an increase in the size of the ultraviolet irradiation device and an increase in the amount of inert gas consumed. Furthermore, if the dimensions between the arc tube 11 and the inner wall of the container are uneven, areas will be created where the inert gas has difficulty flowing, and it may take a long time to replace the air inside the container with inert gas.

[0047] As described above, the dimension between the inner wall of the recess 2a and the external electrode 16 is approximately uniform in the direction perpendicular to the extension direction of the arc tube 11. Furthermore, the dimension between the arc tube 11 and the cover 5 is also approximately uniform. This makes it easy to reduce the volume of the space to which the inert gas is supplied, thereby enabling the ultraviolet irradiation device 100 to be made more compact. Furthermore, if the dimension between the inner wall of the recess 2a and the external electrode 16, and the dimension between the arc tube 11 and the cover 5 are approximately uniform, the inert gas flows more easily, thereby preventing stagnation and other problems that would otherwise occur and lengthen the time required to replace air with inert gas. That is, the ultraviolet irradiation device 1 according to the present embodiment can be made smaller and can optimize purging with an inert gas.

[0048] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0049] 1 barrier discharge lamp, 2 cooling part, 2a recess, 5 cover, 11 arc tube, 12 internal electrode, 16 external electrode, 100 ultraviolet irradiation device

Claims

1. a cooling portion having a recess extending in one direction; a cover provided on the cooling unit on the side where the recessed portion opens; a barrier discharge lamp that is provided in a space defined by the recess of the cooling part and the cover, has an arc tube that extends in the direction in which the recess extends, and irradiates ultraviolet light; Equipped with a surface of the cover facing the arc tube in a direction perpendicular to the extending direction of the arc tube is a curved surface that protrudes in a direction away from the arc tube; An ultraviolet irradiation device, wherein an inert gas is supplied to the space defined by the recess of the cooling part and the cover.

2. 2. The ultraviolet irradiation device according to claim 1, wherein the center of the circle of curvature of the surface of the cover coincides with the central axis of the arc tube.

3. 3. The ultraviolet irradiation device according to claim 1, wherein the cover is in the form of a part of a cylinder.

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