Ultraviolet irradiation device

Abstract

The invention provides an ultraviolet irradiation device capable of realizing miniaturization and suitableness of purge by inert gas. An ultraviolet irradiation device according to an embodiment includes: a cooling unit having a recess extending in one direction; the cover is arranged on the opening side of the concave part of the cooling part; and a barrier discharge lamp which is provided in a space defined by the recess of the cooling unit and the cover, has a light-emitting tube extending in the direction in which the recess extends, and irradiates ultraviolet rays. In the direction orthogonal to the extending direction of the light-emitting tube, the face, opposite to the light-emitting tube, of the cover becomes a curved face protruding in the direction away from the light-emitting tube. An inert gas is supplied to the space defined by the recess of the cooling unit and the cover.

Description

Technical Field

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

[0002] There is an ultraviolet irradiation device including a barrier discharge lamp that irradiates ultraviolet rays. The ultraviolet irradiation device including the barrier discharge lamp is used, for example, for surface treatment such as removal of organic matter (photo cleaning treatment) attached to the surface of an object, surface modification, and formation of an oxide film. The barrier discharge lamp has, for example, an internal electrode provided inside a light emitting tube and an external electrode provided outside the light emitting tube. When an alternating voltage is applied to the internal electrode and the external electrode, dielectric barrier discharge is generated, and ultraviolet rays having a specific wavelength are irradiated corresponding to the type of gas sealed inside the light emitting tube.

[0003] Here, as described above, the external electrode of the barrier discharge lamp is provided outside the light emitting tube. In this case, the external electrode is provided in contact with the light emitting tube. However, a gap sometimes occurs between the external electrode and the light emitting tube. If there is a gap between the external electrode and the light emitting tube, gas discharge sometimes occurs in the gap, and nitrogen oxides are generated from the air (a mixture of nitrogen and oxygen) in the gap. If nitrogen oxides are generated, moisture in the atmosphere sometimes reacts with the nitrogen oxides to generate nitrates. If nitrates are generated, there is a concern that the nitrates adhere to the surface of the object or accumulate in the gap and the light emitting tube is damaged.

[0004] Therefore, a technique has been proposed in which the barrier discharge lamp is housed inside a container and an inert gas such as nitrogen is filled inside the container.

[0005] However, if the barrier discharge lamp is simply housed inside the container, new problems such as enlargement of the ultraviolet irradiation device or an increase in the consumption amount of the inert gas occur. In addition, there is also a problem that the time required to replace the air inside the container with the inert gas becomes long in a region where the inert gas does not easily flow, such as at the corners of the container.

[0006] Therefore, it is desired to develop an ultraviolet irradiation device that can be miniaturized and the purging using the inert gas can be optimized.

[0007] [Prior Art Documents]

[0008] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-72645 Summary of the Invention

[0010] [Problems to be Solved by the Invention]

[0011] The problem to be solved by the present invention is to provide an ultraviolet irradiation device that can achieve miniaturization and proper purging using an inert gas.

[0012] [Technical means for solving the problem]

[0013] The ultraviolet irradiation device according to the embodiment includes: a cooling unit having a recess extending in one direction; a cover provided on the side of the opening of the recess of the cooling unit; and a barrier discharge lamp provided in a space defined by the recess of the cooling unit and the cover, having a light-emitting tube extending in the direction in which the recess extends and irradiating ultraviolet rays. In a direction orthogonal to the direction in which the light-emitting tube extends, the surface of the cover facing the light-emitting tube forms a curved surface protruding away from the light-emitting tube. An inert gas is supplied to the space defined by the recess of the cooling unit and the cover.

[0014] [Effects of the invention]

[0015] According to the embodiment of the present invention, an ultraviolet irradiation device that can achieve miniaturization and proper purging using an inert gas can be provided. Description of the drawings

[0016] Figure 1 It is a schematic side view for illustrating the ultraviolet irradiation device of the present embodiment.

[0017] Figure 2 is Figure 1 A - A sectional view of the ultraviolet irradiation device in

[0018] Figure 3 It is a schematic diagram for illustrating the barrier discharge lamp.

[0019] [Description of reference numerals]

[0020] 1: Barrier discharge lamp

[0021] 2: Cooling unit

[0022] 2a: Recess

[0023] 2b: Flow path

[0024] 2c: Pipe joint

[0025] 2d: Hole

[0026] 2e: Pipe joint

[0027] 3: Lamp socket

[0028] 4: Sealing part

[0029] 5: Cover

[0030] 5a: Sealing member

[0031] 5b: Sealing member

[0032] 5c: Space

[0033] 11: Light-emitting tube

[0034] 11a: Sealing part

[0035] 11b: Conductive part

[0036] 11c: External lead

[0037] 12: Internal electrode

[0038] 12a: Coil

[0039] 12b: Pole wire

[0040] 13: Reflective film

[0041] 14: Bracket

[0042] 15: Wire

[0043] 16: External electrode

[0044] 100: Ultraviolet irradiation device Detailed implementation mode

[0045] Hereinafter, the implementation mode will be illustrated with reference to the drawings. In addition, in each drawing, the same reference numerals are assigned to the same structural components and the detailed description is appropriately omitted.

[0046] Figure 1 is a schematic side view for illustrating the ultraviolet irradiation device 100 of the present implementation mode.

[0047] Figure 2 is Figure 1 the sectional view taken along line A-A of the ultraviolet irradiation device 100 in

[0048] As Figure 1 and Figure 2 shown, the ultraviolet irradiation device 100 has, for example: a barrier discharge lamp 1, a cooling unit 2, a lamp socket 3, a sealing unit 4, and a cover 5.

[0049] The barrier discharge lamp 1 is disposed in the space defined by the concave portion 2a of the cooling unit 2 and the cover 5.

[0050] Figure 3 is a schematic diagram for illustrating the barrier discharge lamp 1.

[0051] As Figure 3 shown, the barrier discharge lamp 1 has, for example: a light-emitting tube 11, an internal electrode 12, a reflective film 13, a bracket 14, a wire 15, and an external electrode 16.

[0052] The light-emitting tube 11 is tubular and has a shape in which the overall length (the length in the tube axis direction) is longer than the tube diameter. The light-emitting tube 11 extends in one direction (e.g., the direction in which the concave portion 2a of the cooling unit 2 extends). The light-emitting tube 11 is, for example, a cylindrical tube. Sealing portions 11a are provided at both end portions in the tube axis direction of the light-emitting tube 11. By providing the sealing portions 11a, the internal space of the light-emitting tube 11 is hermetically sealed. The sealing portions 11a are formed, for example, using a pinch seal method or a shrink seal method.

[0053] Moreover, inside the sealing portion 11a, a conductive portion 11b and an external lead 11c can be provided. For example, one conductive portion 11b can be provided with respect to one sealing portion 11a. The planar shape of the conductive portion 11b is, for example, a quadrilateral. The conductive portion 11b is in the form of a thin film. The conductive portion 11b is formed of, for example, molybdenum foil.

[0054] The external lead 11c is linear and can be provided at least at the sealing portion 11a on the side where the wire 15 is provided. One end portion of the external lead 11c is electrically connected to the conductive portion 11b. Laser welding or resistance welding is performed between the vicinity of the end portion of the external lead 11c and the conductive portion 11b. The other end portion of the external lead 11c protrudes from the sealing portion 11a. The external lead 11c is, for example, a linear body containing molybdenum or the like.

[0055] A gas is enclosed in the internal space of the light-emitting tube 11. In the barrier discharge lamp 1, barrier discharge is performed between the internal electrode 12 and the external electrode 16, and high-energy electrons are given to the enclosed gas to generate excimer-excited molecules. When the excimer-excited molecules return to their original state, ultraviolet rays having a specific main wavelength are generated corresponding to the type of gas.

[0056] Therefore, the gas enclosed in the internal space of the light-emitting tube 11 can be appropriately changed according to the use of the barrier discharge lamp 1. The gas enclosed in the internal space of the light-emitting tube 11 can be, for example, a noble gas such as krypton, xenon, argon, neon, or a mixed gas formed by mixing a plurality of noble gases. Halogen gas or the like can also be further included in the gas as needed.

[0057] The gas pressure (enclosure pressure) at 25°C in the internal space of the light-emitting tube 11 can be set to about 80 kPa to 200 kPa, for example. The gas pressure (enclosure pressure) at 25°C in the internal space of the light-emitting tube 11 can be obtained from the standard state of the gas (Standard Ambient Temperature and Pressure (SATP): temperature 25°C, 1 bar).

[0058] Here, irradiating organic matter with ultraviolet light of short wavelength (deep ultraviolet light) can dissociate the organic matter's bonds. Furthermore, irradiating an atmosphere containing oxygen (e.g., air) with ultraviolet light with a dominant wavelength of 242 nm or less produces ozone and active oxygen species. Ozone and active oxygen species have the effect of decomposing organic matter. Therefore, irradiating organic matter attached to the surface of an object with ultraviolet light of short wavelength can easily remove the organic matter.

[0059] In this case, a barrier discharge lamp 1 (xenon excimer lamp) filled with xenon gas can emit ultraviolet light with a dominant wavelength of 172 nm. Therefore, a barrier discharge lamp 1 filled with xenon gas can increase the irradiation energy and enhance the ability to generate ozone and active oxygen. Therefore, for example, a barrier discharge lamp 1 filled with xenon gas is suitable for optical cleaning of the surface of a glass plate used in a flat-panel display.

[0060] The light emitting tube 11 is formed of a material having a high transmittance for ultraviolet rays having a main wavelength of 200 nm or less, for example, or can be formed of synthetic quartz glass.

[0061] The internal electrode 12 is provided inside the arc tube 11. For example, the internal electrode 12 includes a coil 12a and a pole wire 12b. The coil 12a and pole wire 12b can be integrally formed. For example, the coil 12a and pole wire 12b are formed by plastic working a wire rod. The wire rod has a diameter of, for example, approximately 0.2 mm to 1.0 mm. The wire rod is made of, for example, tungsten or doped tungsten with potassium or other additives.

[0062] The coil 12a is spiral-shaped 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.

[0063] Polar wires 12b are provided at either end of coil 12a. These wires are linear and extend from the ends of coil 12a along the axis of the arc tube 11. The ends of polar wires 12b are electrically connected to the conductive portion 11b within the sealing portion 11a. The vicinity of the ends of polar wires 12b can be laser welded or resistance welded to the conductive portion 11b.

[0064] 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 film-shaped and is provided on the inner wall of the light-emitting tube 11. The reflective film 13 reflects ultraviolet light generated within the interior of the light-emitting tube 11 and not directed in the irradiation direction back in the irradiation direction. The provision of the reflective film 13 improves the efficiency of ultraviolet light extraction. Furthermore, the reflective film 13 reduces the area of the light-emitting tube 11 directly incident with ultraviolet light, thereby suppressing chemical structural changes in the light-emitting tube 11 caused by ultraviolet light.

[0065] The thickness of the reflective film 13 can be set to around 100 μm to 300 μm, for example. The reflective film 13 contains SiO2, for example. Moreover, the reflective film 13 can also contain particles that scatter ultraviolet rays. The particles that scatter ultraviolet rays contain aluminum oxide or the like, for example.

[0066] In addition, the reflective film 13 may not be necessarily provided and can be omitted. However, if the reflective film 13 is provided, the extraction efficiency of ultraviolet rays can be improved, and chemical structural changes of the light-emitting tube 11 caused by ultraviolet rays can be suppressed.

[0067] The brackets 14 are respectively provided at both end portions in the tube axis direction of the light-emitting tube 11. The brackets 14 cover the end portions of the light-emitting tube 11. The brackets 14 are formed of an insulating material, for example. The brackets 14 can be formed of steatite, aluminum oxide, or the like, for example. The brackets 14 can be in contact with the external electrodes 16 or can be separated from the external electrodes 16.

[0068] The lead wire 15 is electrically connected to the end portion of the external lead 11c exposed from the sealing portion 11a. The lead wire 15 is electrically connected to the internal electrode 12 via the external lead 11c and the conductive portion 11b. The lead wire 15 is electrically connected to a lighting circuit provided outside the ultraviolet irradiation device 100, for example. In addition, the lead wire 15 can be provided only on one end side of the light-emitting tube 11 as shown in Figure 3 or can be respectively provided on both end portions of the light-emitting tube 11.

[0069] As in Figure 2 and Figure 3 shown, the external electrode 16 is provided outside the light-emitting tube 11.

[0070] The external electrode 16 extends along the outer surface of the light-emitting tube 11 in the tube axis direction of the light-emitting tube 11. The external electrode 16 is provided between the outer surface of the light-emitting tube 11 and the inner wall of the concave portion 2a of the cooling portion 2. The external electrode 16 faces the internal electrode 12 (coil 12a). In the case where the reflective film 13 is provided, the external electrode 16 can be provided at a position facing the reflective film 13.

[0071] The thickness of the external electrode 16 is 0.1 mm or more and 1.0 mm or less, for example. The external electrode 16 can be formed of a conductive material such as metal. The external electrode 16 is formed of stainless steel, aluminum, or the like, for example. In addition, when the barrier discharge lamp 1 is lit, ultraviolet rays and heat are generated together. Therefore, if the external electrode 16 contains a material with a high thermal conductivity such as metal, the external electrode 16 can also be used as a heat dissipation portion.

[0072] As in Figure 1 and Figure 2As shown, the cooling part 2 faces the light-emitting tube 11 with the external electrode 16 therebetween. The cooling part 2 extends along 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.

[0073] As Figure 2 shown, a recess 2a can be provided on one surface of the cooling part 2. The recess 2a extends along the tube axis direction of the light-emitting tube 11. The external electrode 16 and the light-emitting tube 11 of the barrier discharge lamp 1 can be provided, for example, inside the recess 2a.

[0074] In the above case, a gap is provided between the inner wall of the recess 2a and the external electrode 16. The center of the curvature circle of the inner wall of the recess 2a can overlap with the central axis of the light-emitting tube 11, for example. If so, in the direction orthogonal to the extending direction of the light-emitting tube 11, the dimension between the inner wall of the recess 2a and the external electrode 16 can be substantially uniform.

[0075] The cooling part 2 is formed of a material with high thermal conductivity. The cooling part 2 can be formed of a metal such as aluminum or stainless steel, for example. Also, as Figure 2 shown, a flow path 2b can be provided inside the cooling part 2. The flow path 2b extends along the extending direction of the cooling part 2. For example, a pair of pipe connectors 2c can be connected to the flow path 2b. The cooling medium supplied to the flow path 2b from one of the pipe connectors 2c flows inside the flow path 2b and is discharged to the outside of the cooling part 2 from the other pipe connector 2c. The cooling medium is water or the like, for example. If the cooling medium flows inside the flow path 2b, the heat generated in the barrier discharge lamp 1 can be dissipated efficiently.

[0076] The lamp holder 3 holds the barrier discharge lamp 1 detachably. The lead wire 15 and the external electrode 16 of the barrier discharge lamp are electrically connected to a lighting circuit or the like provided outside the ultraviolet irradiation device 100 via the lamp holder 3. The lighting circuit has, for example, an inverter that converts the power from an AC power supply into high-voltage and high-frequency (for example, a sine wave with a frequency of 37 kHz) power. For example, the lighting circuit lights the barrier discharge lamp 1 with a lamp power of about 2.4 kW.

[0077] The sealing part 4 seals the space defined by the cooling part 2 and the cover 5 airtightly. Also, the sealing part 4 holds the lamp holder 3 detachably. The sealing part 4 is provided at both end parts of the cooling part 2 and the cover 5, respectively.

[0078] The cover 5 is provided on the side of the opening of the recess 2a of the cooling section 2. The cover 5 extends in the tube axis direction of the barrier discharge lamp 1. The cover 5 faces the light-emitting tube 11 of the barrier discharge lamp 1 and the cooling section 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. Therefore, the cover 5 is formed of a material having a high transmittance for ultraviolet rays with a main wavelength of 200 nm or less, for example. For example, the cover 5 can be formed of synthetic quartz glass.

[0079] The end portion of the cover 5 on the cooling section 2 side is provided to be airtight with the end portion of the opening of the recess 2a of the cooling section 2 via the sealing member 5a. The end portion of the cover 5 on the sealing section 4 side is provided to be airtight with the sealing section 4 via the sealing member 5b.

[0080] In the direction orthogonal to the direction in which the light-emitting tube 11 extends, the surface of the cover 5 facing the light-emitting tube 11 becomes a curved surface protruding in a direction away from the light-emitting tube 11. The center of the curvature circle of the surface of the cover 5 facing the light-emitting tube 11 can overlap with the central axis of the light-emitting tube 11, for example. For example, the shape of the cover 5 can be set as a part of a cylinder. In this case, the central axis of the cylinder can overlap with the central axis of the light-emitting tube 11, for example.

[0081] If so, in the direction orthogonal to the direction in which the light-emitting tube 11 extends, the dimension between the light-emitting tube 11 and the cover 5 can be substantially uniform.

[0082] The space 5c between the light-emitting tube 11 and the cover 5 is connected to the space between the inner wall of the recess 2a of the cooling section 2 and the external electrode 16. A pipe 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 supplied to the hole 2d of the cooling section 2 from the pipe joint 2e provided on one end side of the cooling section 2 flows into the space between the inner wall of the recess 2a and the external electrode 16 and the space 5c between the light-emitting tube 11 and the cover 5. In addition, the inert gas flowing into these spaces is discharged to the outside of the cooling section 2 from the pipe joint 2e provided on the other end side of the cooling section 2.

[0083] That is, the inert gas is supplied to the space defined by the recess 2a of the cooling section 2 and the cover 5. In addition, the supply of the inert gas can be continuous or intermittent. In addition, the inert gas can also be supplied as needed. Among them, if the supply of the inert gas is continuous, the reliability of the ultraviolet irradiation device 100 can be improved or the maintenance cycle can be extended.

[0084] Here, sometimes gas discharge occurs in the gap between the outer electrode 16 and the light-emitting tube 11. In such a case, if air (a mixture of nitrogen and oxygen) exists in the gap, nitrogen oxides are sometimes generated. Additionally, if moisture exists in the atmosphere of the gap, the nitrogen oxides sometimes react with the moisture to form nitrates. If nitrates are formed, there is a concern that the nitrates adhere to the inner surface of the cover 5 and obstruct the irradiation of ultraviolet rays, or that the nitrates accumulate in the gap between the outer electrode 16 and the light-emitting tube 11 and the light-emitting tube 11 is damaged.

[0085] Therefore, the inert gas supplied to the space between the inner wall of the recess 2a and the outer electrode 16 and the space 5c between the light-emitting tube 11 and the cover 5 is preferably a gas that does not contain oxygen. For example, the inert gas can be nitrogen or a noble gas, etc.

[0086] In such a case, the barrier discharge lamp 1, the cooling unit 2, and the lamp socket 3 can be housed inside a container, and the inside of the container can be filled with an inert gas. However, if this is done, a large-volume container is required, resulting in the enlargement of the ultraviolet irradiation device or an increase in the consumption of the inert gas. Additionally, if the dimensions between the light-emitting tube 11 and the inner wall of the container are uneven, a region where the inert gas does not easily flow is generated, and there is a concern that the time required to replace the air inside the container with the inert gas becomes longer.

[0087] As described above, in the direction orthogonal to the extending direction of the light-emitting tube 11, the dimensions between the inner wall of the recess 2a and the outer electrode 16 are substantially uniform. Additionally, the dimensions between the light-emitting tube 11 and the cover 5 are substantially uniform. Therefore, it is easy to reduce the volume of the space for supplying the inert gas, and thus miniaturization of the ultraviolet irradiation device 100 can be achieved. Additionally, if the dimensions between the inner wall of the recess 2a and the outer electrode 16 and the dimensions between the light-emitting tube 11 and the cover 5 are substantially uniform, the inert gas easily flows, and thus it is possible to suppress the occurrence of stagnation, etc., and make the time for replacing the air with the inert gas longer.

[0088] That is, according to the ultraviolet irradiation device 100 of the present embodiment, miniaturization and appropriate purging using an inert gas can be achieved.

[0089] Above, several embodiments of the present invention have been exemplified, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, changes, etc. can be made without departing from the gist of the invention. These embodiments or their modifications are included in the scope or gist of the invention and are included in the invention described in the claims and its equivalents. Moreover, the above-described embodiments can be implemented in combination with each other.

Claims

1. An ultraviolet irradiation device, characterized in that, Comprising: A cooling part having a recess extending in one direction; A cover disposed on the side of the opening of the recess of the cooling part; And A barrier discharge lamp disposed in the space defined by the recess of the cooling part and the cover, having a light-emitting tube extending in the direction in which the recess extends, and irradiating ultraviolet rays, In a direction orthogonal to the direction in which the light-emitting tube extends, the surface of the cover facing the light-emitting tube becomes a curved surface protruding away from the light-emitting tube, An inert gas is supplied to the space defined by the recess of the cooling part and the cover.

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

3. The ultraviolet irradiation device according to claim 1 or 2, characterized in that, The shape of the cover is a part of a cylinder.

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