Ultraviolet irradiation device

Abstract

The deformation of the external electrodes of the ultraviolet irradiation device will be reduced, and the purging with inert gas will be optimized. [Solution] The ultraviolet irradiation device comprises: an internal electrode extending inside a discharge tube; an external electrode having a curved portion extending in a first direction along the outer wall of the discharge tube and a plurality of mounting portions arranged in the first direction; the discharge tube and a cooling unit having the curved portion and a first recess extending in the first direction; a cover provided on the side of the cooling unit where the first recess opens and facing the discharge tube through a space; and a plurality of holders provided on the side of the cooling unit where the first recess opens, arranged in the first direction. Each of the plurality of holders is adjustable in the position of the curved portion relative to the discharge tube. An inert gas can be supplied to the space between the discharge tube 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 a barrier discharge lamp is used, for example, for surface treatment such as removal of organic substances (photo cleaning treatment) adhering 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 occurs, and ultraviolet rays having a specific wavelength are irradiated according to the type of gas enclosed inside the light emitting tube.

[0003] In recent years, in order to perform a wider range of processing, the length of the barrier discharge lamp in the tube axis direction tends to become longer. When the length of the barrier discharge lamp in the tube axis direction becomes longer, the length of the external electrode in the tube axis direction becomes longer. When the length of the external electrode becomes longer, the amount of deformation of the external electrode tends to increase due to the generated heat. When the amount of deformation of the external electrode increases, the distance between the internal electrode and the external electrode may change, and the discharge state may change. When the discharge state changes, the uniformity decreases, and processing unevenness is likely to occur.

[0004] Furthermore, when the length of the barrier discharge lamp in the tube axis direction becomes longer, a gap is likely to occur between the external electrode and the light emitting tube. When there is a gap between the external electrode and the light emitting tube, atmospheric 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, there is a possibility that the moisture in the atmosphere reacts with the nitrogen oxides to generate nitrates. When nitrates are generated, the nitrates may adhere to the surface of the object or accumulate in the gap, and the light emitting tube may be damaged.

[0005] Therefore, a technique has been proposed to supply an inert gas to the gap between the external electrode and the discharge tube. By supplying an inert gas to the gap between the external electrode and the discharge tube, even if an air discharge occurs in the gap, the generation of the aforementioned nitrogen oxides can be suppressed.

[0006] However, simply supplying an inert gas to the gap between the external electrode and the discharge tube presents new challenges, such as variations in the concentration of the inert gas in the gap and increased leakage of the supplied inert gas, leading to increased consumption of the inert gas.

[0007] Therefore, there was a need for the development of an ultraviolet irradiation device that could reduce the deformation of the external electrodes and optimize purging with inert gas. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2021-197267 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The problem that this invention aims to solve is to provide an ultraviolet irradiation device that can reduce the amount of deformation of the external electrode and optimize purging with an inert gas. [Means for solving the problem]

[0010] The ultraviolet irradiation device according to the embodiment comprises: a light-emitting tube extending in a first direction; an internal electrode extending inside the light-emitting tube; an external electrode having a curved portion extending in the first direction along the outer wall of the light-emitting tube and a plurality of mounting portions provided at predetermined intervals and arranged in the first direction at each of the ends on both sides of the curved portion in a second direction intersecting the first direction; a cooling unit on which the light-emitting tube and the curved portion are provided and which has a first recess extending in the first direction; a cover provided on the side of the cooling unit on which the first recess opens and facing the light-emitting tube through a space; a packing provided between each of the ends on both sides of the cover in the second direction and the side of the cooling unit on which the first recess opens, and extending in the first direction; and a plurality of plate-shaped holders provided on the side of the cooling unit on which the first recess opens, arranged in the first direction. Each of the plurality of holders is adjustable in the position of the curved portion relative to the light-emitting tube. An inert gas can be supplied to the space between the light-emitting tube and the cover. [Effects of the Invention]

[0011] According to embodiments of the present invention, it is possible to provide an ultraviolet irradiation device that can reduce the amount of deformation of the external electrode and optimize purging with an inert gas. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic exploded view illustrating the ultraviolet irradiation device according to this embodiment. [Figure 2] Figure 1 is a cross-sectional view of the ultraviolet irradiation device along line AA. [Figure 3] This is a schematic diagram illustrating a barrier discharge lamp. [Figure 4] This is a schematic perspective view illustrating holders positioned opposite each other. [Modes for carrying out the invention]

[0013] 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 descriptions will be omitted as appropriate.

[0014] Figure 1 is a schematic exploded view illustrating the ultraviolet irradiation device 100 according to this embodiment. Figure 2 is a cross-sectional view of the ultraviolet irradiation device 100 in Figure 1, along line AA. As shown in Figures 1 and 2, the ultraviolet irradiation device 100 includes, for example, a barrier discharge lamp 1, a cooling unit 2, a clamp 3, a holder 4, and a cover 5.

[0015] Figure 3 is a schematic diagram illustrating barrier discharge lamp 1. As shown in Figure 3, the barrier discharge lamp 1 includes, for example, a discharge tube 11, an internal electrode 12, a reflective film 13, a base 14, lead wires 15, and an external electrode 16.

[0016] The discharge tube 11 is substantially cylindrical in shape, and its total length (length in the central axis direction) is longer than its diameter. The discharge tube 11 extends in one direction. Sealing portions 11a are provided at each end of the discharge tube 11 in the direction in which it extends (corresponding to an example of the first direction). By providing the sealing portions 11a, the internal space of the discharge tube 11 is hermetically sealed. The sealing portions 11a are formed, for example, using a pinch seal method or a shrink seal method.

[0017] 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 is in the form of a thin film and is formed from, for example, molybdenum foil.

[0018] The outer lead 11c is linear and can be provided at the sealing portion 11a on at least 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 other end of the outer lead 11c is exposed from the sealing portion 11a. The outer lead 11c is, for example, a linear body containing molybdenum or the like.

[0019] The internal space of the arc discharge lamp 11 is filled with gas. In the barrier discharge lamp 1, barrier discharge is performed between the internal electrode 12 and the external electrode 16 to give high-energy electrons 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 according to the type of gas. For example, when xenon gas is enclosed in the internal space of the arc discharge lamp 11, ultraviolet rays having a main wavelength of 172 nm are generated.

[0020] Therefore, the gas enclosed in the internal space of the arc discharge lamp 11 can be appropriately changed according to the use of the ultraviolet irradiation device 100. The gas enclosed in the internal space of the arc discharge lamp 11 can be, for example, a noble gas such as krypton, xenon, argon, neon, or a mixed gas in which a plurality of types of noble gases are mixed. The gas can further contain a halogen gas or the like as necessary.

[0021] The pressure (enclosure pressure) of the gas in the internal space of the arc discharge lamp 11 at 25°C can be, for example, about 80 kPa to 200 kPa. The pressure (enclosure pressure) of the gas in the internal space of the arc discharge lamp 11 at 25°C can be determined by the standard state of the gas (SATP (Standard Ambient Temperature and Pressure): temperature 25°C, 1 bar).

[0022] The arc discharge lamp 11 is formed of a material having a high transmittance of ultraviolet rays. For example, the arc discharge lamp 11 can be formed of synthetic quartz glass.

[0023] The internal electrode 12 is provided inside the arc discharge lamp 11 and extends inside the arc discharge lamp 11. The internal electrode 12 includes, 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 from, for example, a wire containing tungsten or doped tungsten. The wire diameter is, for example, about 0.2 mm to 1.0 mm.

[0024] 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 central axis 11e of the discharge tube 11 through the central region of the internal space of the discharge tube 11.

[0025] 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 central axis 11e of the discharge tube 11. The ends of legs 12b are electrically connected to the conductive part 11b inside the sealing part 11a.

[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 is provided on the inner wall of the discharge tube 11. When viewed from the direction in which the discharge tube 11 extends, the reflective film 13 has an aperture 13a that faces the cooling unit 2 on either side of the central axis 11e of the discharge tube 11. The reflective film 13 reflects ultraviolet light generated in the internal space of the discharge tube 11 and directed toward the cooling unit 2, and emits it out of the discharge tube 11 through the aperture 13a.

[0027] The thickness of the reflective film 13 is, 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.

[0028] 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.

[0029] The base 14 is provided at each end of the discharge tube 11 in the direction in which the discharge tube 11 extends. The base 14 covers the ends of the discharge tube 11. The base 14 is formed from an insulating material such as steatite or aluminum oxide.

[0030] 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.

[0031] As shown in Figures 1 to 3, the external electrode 16 is plate-shaped and is provided on the outside of the discharge tube 11. The external electrode 16 has, for example, a curved portion 16a and a plurality of mounting portions 16b. The curved portion 16a and the plurality of mounting portions 16b can be formed integrally.

[0032] The curved portion 16a extends along the outer wall of the discharge tube 11 in the direction in which the discharge tube 11 extends. The curved portion 16a has a curved shape that conforms to the outer wall of the discharge tube 11. The curved portion 16a is provided between the outer wall of the discharge tube 11 and the inner wall of the recess 2a of the cooling section 2 (corresponding to an example of the first recess). The curved portion 16a faces the internal electrode 12 (coil 12a). If a reflective film 13 is provided, the curved portion 16a can be provided in a position facing the reflective film 13.

[0033] Furthermore, when viewed from the direction in which the discharge tube 11 extends, it is preferable that the central angle of the curved portion 16a be between 180° and 300°. This ensures that the required amount of ultraviolet light is generated and suppresses a decrease in the efficiency of ultraviolet light extraction.

[0034] The external electrode 16 can be formed from, for example, a metal plate with a thickness of 0.1 mm or more and 1.0 mm or less. The metal plate can include, for example, stainless steel or aluminum. If the external electrode 16 is formed from a metal plate, it can also be used as a heat dissipation part.

[0035] In this case, the discharge tube 11, internal electrode 12, and reflective film 13 are more prone to wear than the external electrode 16. Therefore, if the discharge tube 11 can be detached from the external electrode 16, maintenance can be improved and running costs can be reduced.

[0036] For example, as shown in Figures 1 and 2, the external electrode 16 has a plurality of mounting portions 16b. In a direction intersecting the direction in which the discharge tube 11 extends (corresponding to an example of a second direction), the plurality of mounting portions 16b can be provided at each of the ends on both sides of the curved portion 16a. Also, in the direction in which the discharge tube 11 extends, the plurality of mounting portions 16b can be arranged side by side at predetermined intervals. The plurality of mounting portions 16b protrude from the ends of the curved portion 16a in a direction intersecting the direction in which the discharge tube 11 extends. Holes can be provided in the mounting portions 16b into which fastening members such as screws are inserted.

[0037] An AC voltage is applied to the internal electrode 12 and the external electrode 16 from a lighting circuit located 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 and high-frequency power (for example, a sine wave with a frequency of 37 kHz). For example, the lighting circuit applies about 2.4 kW of lamp power to the internal electrode 12 and the external electrode 16.

[0038] As shown in Figures 1 and 2, the cooling section 2 faces the discharge tube 11 with the external electrode 16 in between. The cooling section 2 extends in the direction in which the discharge tube 11 extends. A recess 2a opens at one end 2c of the cooling section 2 in a direction intersecting the direction in which the discharge tube 11 extends. The recess 2a extends in the direction in which the discharge tube 11 extends. The discharge tube 11 and the curved portion 16a of the external electrode 16 can be provided inside the recess 2a. The inner wall of the recess 2a faces the discharge tube 11 and the curved portion 16a. The inner wall of the recess 2a has a concave curved surface shape that follows the outer wall of the discharge tube 11.

[0039] In this case, as shown in Figure 2, a gap can be provided between the inner wall of the recess 2a and the curved portion 16a. If a gap is provided between the inner wall of the recess 2a and the curved portion 16a, manufacturing errors in the outer diameter dimensions of the discharge tube 11 and the curved portion 16a can be absorbed. In addition, it is possible to suppress the discharge tube 11 from coming into contact with the cooling portion 2 via the curved portion 16a due to thermal expansion when the barrier discharge lamp 1 is lit. Therefore, it is possible to suppress damage to the discharge tube 11 when the barrier discharge lamp 1 is lit.

[0040] The center of the curvature circle of the inner wall of the recess 2a can be, for example, aligned with the central axis 11e of the discharge tube 11. When viewed from the direction in which the discharge tube 11 extends, the central angle of the recess 2a with respect to the central axis 11e can be 180° or less. This makes it easy to install and remove the barrier discharge lamp 1 through the opening of the recess 2a. As a result, the maintainability of the ultraviolet irradiation device 100 can be improved.

[0041] Furthermore, as shown in Figure 1, a plurality of recesses 2d (corresponding to an example of a second recess) can be provided at the end 2c of the cooling section 2. In the direction in which the discharge tube 11 extends, the plurality of recesses 2d can be arranged in a line with predetermined intervals between them. Each of the plurality of recesses 2d can be provided at a position opposite each of the plurality of mounting portions 16b of the external electrode 16. As will be described later, each of the plurality of recesses 2d is provided with a holder 4 and a mounting portion 16b of the external electrode 16. Therefore, the spacing, number, and arrangement of the plurality of recesses 2d can be the same as the spacing, number, and arrangement of the plurality of mounting portions 16b of the external electrode 16.

[0042] Furthermore, the multiple recesses 2d can be positioned opposite each other in a direction intersecting the direction in which the discharge tube 11 extends. In this way, a pair of holders 4 can be positioned opposite each other with the discharge tube 11 in between. Therefore, when adjusting the position of the external electrode 16 using the holders 4, as described later, it is possible to adjust the external electrode 16 to approximately the same position in a direction intersecting the direction in which the discharge tube 11 extends.

[0043] The recess 2d opens to the end 2c of the cooling section 2 and to at least the inner wall of the recess 2a. In this case, as shown in Figure 1, if the recess 2d opens to the outer wall of the cooling section 2 and the inner wall of the recess 2a in a direction intersecting the direction in which the discharge tube 11 extends, the position adjustment by the holder 4 described later will be easier.

[0044] As shown in Figure 1, the cooling unit 2 can be provided, for example, in the housing 200 in which the ultraviolet irradiation device 100 is installed. The cooling unit 2 dissipates the heat generated when the barrier discharge lamp 1 is lit. Therefore, 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.

[0045] Furthermore, as shown in Figure 2, a flow path 2b can be provided inside the cooling unit 2. The flow path 2b extends in the direction in which the discharge tube 11 extends. A refrigerant such as water is supplied to one end of the flow path 2b via a pipe fitting or the like. The refrigerant that has flowed inside the flow path 2b is discharged to the outside of the cooling unit 2 from the other end of the flow path 2b via a pipe fitting or the like.

[0046] As shown in Figure 1, the clamp 3 can be provided on each of the ends of the barrier discharge lamp 1. The clamp 3 detachably holds the ends of the barrier discharge lamp 1. The clamp 3 has, for example, a base 3a and a fixing part 3b. The base 3a can be provided, for example, on a housing 200 on which an ultraviolet irradiation device 100 is installed. The fixing part 3b is detachably provided, for example, on the end of the base 3a opposite to the housing 200 side using fastening members such as screws. A recess is provided on the end of the base 3a opposite to the housing 200 side. A recess is provided on the end of the fixing part 3b on the base 3a side. When the fixing part 3b is attached to the base 3a, the base 14 of the barrier discharge lamp 1 is held by the recess of the base 3a and the recess of the fixing part 3b. Furthermore, the clamp 3 can be equipped with a packing that seals the space defined by the cooling section 2 and the cover 5 in an airtight manner.

[0047] The material of clamp 3 is not particularly limited, as long as it has a certain degree of rigidity, heat resistance, and resistance to ultraviolet rays. Clamp 3 can be made from a metal such as aluminum or stainless steel.

[0048] As shown in Figures 1 and 2, the multiple holders 4 are plate-shaped and arranged in the direction in which the light-emitting tube 11 extends, on the side where the recess 2a of the cooling section 2 opens. The holders 4 are provided between the bottom of the recess 2d of the cooling section 2 and the mounting portion 16b of the external electrode 16. The mounting portion 16b of the external electrode 16 and the holders 4 are attached to the bottom of the recess 2d of the cooling section 2 using fastening members such as screws. The holders 4 can be made from, for example, a metal such as stainless steel or a resin such as fluororesin.

[0049] Figure 4 is a schematic perspective view illustrating holders 4 located at opposing positions. The configurations of the multiple holders 4 can be the same or different. In this case, if the configurations of the multiple holders 4 are the same, it is possible to reduce manufacturing costs and simplify the management of parts inventory.

[0050] As shown in Figure 4, one end 4a of the holder 4 has a concave curved surface that conforms to the outer wall of the discharge tube 11. The center of the circle of curvature of end 4a can be, for example, aligned with the central axis 11e of the discharge tube 11. In this case, the radius of curvature of end 4a can be the same as half the diameter of the discharge tube 11, or slightly larger. Alternatively, end 4a may be an inclined surface that approximates the shape of the outer wall of the discharge tube 11. When installing the holder 4 inside the recess 2d of the cooling unit 2, the end 4a side should face the outer wall of the discharge tube 11.

[0051] Furthermore, the holder 4 can be provided with a hole 4b that penetrates in the thickness direction. The hole 4b extends in the direction toward the end 4a. If a hole 4b extending toward the end 4a is provided, as shown in Figure 2, it becomes easier to adjust the position between the end 4a and the curved portion 16a of the external electrode 16, and consequently, the position between the curved portion 16a and the discharge tube 11, in a direction intersecting the direction in which the discharge tube 11 extends. In other words, each of the multiple holders 4 can adjust the position of the curved portion 16a relative to the discharge tube 11.

[0052] If multiple holders 4 are provided, the barrier discharge lamp 1 (discharge tube 11) can be held in the cooling unit 2. Furthermore, if multiple holders 4 are provided, it is possible to suppress the amount of deformation of the curved portion 16a due to the heat generated when the barrier discharge lamp 1 is lit. As a result, it is possible to suppress changes in the distance between the coil 12a of the internal electrode 12 and the curved portion 16a, which changes the discharge state, thus suppressing the occurrence of uneven processing due to a decrease in uniformity.

[0053] When multiple holders 4 are removed from the cooling unit 2, the barrier discharge lamp 1 can be removed from the opening of the recess 2a of the cooling unit 2. In other words, if multiple holders 4 are provided, it is possible to suppress displacement of the barrier discharge lamp 1 and adjust the position of the curved portion 16a of the external electrode 16 in a direction intersecting the direction in which the discharge tube 11 extends, without impairing the maintainability of the ultraviolet irradiation device 100.

[0054] As mentioned above, a gap is provided between the inner wall of the recess 2a of the cooling unit 2 and the curved portion 16a of the external electrode 16. In addition, a gap may also be created between the curved portion 16a and the discharge tube 11. As mentioned above, such gaps can absorb manufacturing errors in the outer diameter of the discharge tube 11 and suppress contact between the discharge tube 11 and the cooling unit 2 due to thermal expansion.

[0055] However, if such gaps exist, air discharge may occur in the gaps. In this case, if the gap contains air (a mixture of nitrogen and oxygen) in the atmosphere where the ultraviolet irradiation device 100 is installed, nitrogen oxides may be generated when air discharge occurs. When nitrogen oxides are generated, they may react with moisture in the atmosphere to produce nitrates. When nitrates are generated, they may adhere to the surface of the object being irradiated with ultraviolet light, or accumulate in the gaps, potentially damaging the discharge tube 11.

[0056] Therefore, the ultraviolet irradiation device 100 according to this embodiment is provided with a cover 5. As shown in Figures 1 and 2, the cover 5 is provided on the side of the cooling section 2 where the recess 2a opens. The cover 5 extends in the direction in which the discharge tube 11 extends. The cover 5 faces the discharge tube 11 across a space. When viewed from the direction in which the discharge tube 11 extends, the surface of the cover 5 facing the discharge tube 11 is a curved surface that protrudes away from the discharge tube 11. The center of the circle of curvature of the surface of the cover 5 facing the discharge tube 11 can coincide with, for example, the central axis 11e of the discharge tube 11. For example, the cover 5 can be part of a cylinder. In this case, the central axis of the cylinder can coincide with, for example, the central axis 11e of the discharge tube 11.

[0057] In this way, the dimensions of the space between the cover 5 and the discharge tube 11 can be made approximately uniform. As a result, the inert gas, which will be described later, can flow smoothly through the space between the cover 5 and the discharge tube 11, thereby suppressing stagnation and preventing the time required to replace the air with the inert gas from being prolonged. In addition, since the volume of the space to which the inert gas is supplied can be reduced, the ultraviolet irradiation device 100 can be made more compact.

[0058] Ultraviolet light emitted from the barrier discharge lamp 1 enters the object being irradiated with ultraviolet light through the cover 5. Therefore, the cover 5 is made of a material that has high transmittance of ultraviolet light with a dominant wavelength of 200 nm or less. For example, the cover 5 can be made of synthetic quartz glass.

[0059] A packing 5a is provided between each of the ends of the cover 5 in a direction intersecting the direction in which the discharge tube 11 extends, and the side of the cooling section 2 where the recess 2a opens. The packing 5a can be made of an elastic material such as rubber. The packing 5a extends in the direction in which the discharge tube 11 extends. Also, as shown in Figure 1, the end 2c of the cooling section 2 is provided with a pair of recesses 2c1 (corresponding to an example of a third recess) that extend in the direction in which the discharge tube 11 extends and open into the end 2c of the cooling section 2. The pair of recesses 2c1 face each other with the recess 2a of the cooling section 2 in between.

[0060] One end of the packing 5a is provided inside the recess 2c1. The recess 2c1 holds one end of the packing 5a. In this case, the packing 5a can be held in the recess 2c1 by elastic force, or it can be joined to the recess 2c1 using an adhesive or the like. However, if the packing 5a is held in the recess 2c1 by elastic force, it becomes easier to remove the cover 5, packing 5a, external electrode 16, and consequently the barrier discharge lamp 1 from the cooling unit 2 during maintenance. Therefore, the maintainability of the ultraviolet irradiation device 100 can be further improved.

[0061] Furthermore, if a recess 2c1 for holding the packing 5a is provided at the end 2c of the cooling unit 2, it is possible to prevent the packing 5a and cover 5 from shifting position or from falling off the cooling unit 2.

[0062] A recess 5a1 is provided at the end of the packing 5a opposite to the cooling section 2. The end of the cover 5, in a direction intersecting the direction in which the light-emitting tube 11 extends, is detachably fitted into the recess 5a1 of the packing 5a.

[0063] In the direction in which the discharge tube 11 extends, each end of the cover 5 is detachably attached to the clamp 3 via a packing. Similarly, in the direction in which the discharge tube 11 extends, each end of the cooling section 2 is detachably attached to the clamp 3 via a packing.

[0064] Therefore, the space between the cover 5 and the discharge tube 11, the gap between the inner wall of the recess 2a of the cooling section 2 and the curved portion 16a of the external electrode 16, and the gap between the curved portion 16a and the discharge tube 11 are sealed to be airtight. These gaps are in communication with each other, and an inert gas is supplied from the outside.

[0065] For example, as shown in Figure 2, the cooling section 2 can be provided with a plurality of holes 2f that open into the inner wall of the recess 2a. In the direction in which the light-emitting tube 11 extends, the holes 2f can be provided on one end side of the cooling section 2 and on the other end side of the cooling section 2.

[0066] An inert gas is supplied to a hole 2f provided at one end of the cooling unit 2. The supplied inert gas flows through the aforementioned gap and space and is discharged to the outside of the cooling unit 2 through a hole 2f provided at the other end of the cooling unit 2. If an inert gas is supplied to the aforementioned gap, the generation of nitrates can be suppressed even if an air discharge occurs in the gap.

[0067] In this case, the supply of inert gas may be continuous or intermittent. Furthermore, the inert gas may be supplied as needed. However, a continuous supply of inert gas can improve the reliability of the ultraviolet irradiation device 100 and extend the maintenance cycle.

[0068] An inert gas can be any gas that does not contain oxygen. For example, inert gases include nitrogen gas and noble gases.

[0069] Here, as shown in Figure 1, the packing 5a extending in the direction in which the discharge tube 11 extends will straddle the holder 4 and the mounting portion 16b of the external electrode 16, which are provided in the recess 2d of the cooling section 2. In this case, if the depth dimension of the recess 2d is smaller than the sum of the thickness of the holder 4 and the thickness of the mounting portion 16b of the external electrode 16, the packing 5a may be lifted, potentially creating a large gap between the packing 5a and the end portion 2c of the cooling section 2. If the depth dimension of the recess 2d is larger than the sum of the thickness of the holder 4 and the thickness of the mounting portion 16b of the external electrode 16, a large gap may be created between the packing 5a and the mounting portion 16b of the external electrode 16. If a large gap is created, the amount of inert gas leaking out through the gap will increase, which may increase running costs.

[0070] According to the findings of the present inventors, if the difference between the depth dimension of the recess 2d and the sum of the thickness of the holder 4 and the thickness of the mounting portion 16b of the external electrode 16 is ±0.5 mm or less, the amount of inert gas leaking from the aforementioned gap can be kept within an acceptable range.

[0071] Furthermore, a recess may be provided at the end of the packing 5a on the cooling section 2 side, opposite to the recess 2d. The depth of the recess can be approximately the same as the depth of the recess 2c1. In this way, when the packing 5a is installed inside the recess 2c1, the position of the bottom of the recess provided at the end of the packing 5a on the cooling section 2 side can be set to the position of the end 2c of the cooling section 2. Therefore, when the packing 5a is installed inside the recess 2c1, it is possible to suppress the formation of a gap between the packing 5a and the mounting portion 16b of the external electrode 16.

[0072] As described above, with the ultraviolet irradiation device 100 according to this embodiment, the inert gas can flow smoothly through the gap between the cover 5 and the discharge tube 11. Therefore, variations in the concentration of the inert gas in the gap can be suppressed, and thus the generation of nitrates can be effectively suppressed. Furthermore, since a packing 5a is provided between the cover 5 and the cooling unit 2, the amount of leakage of the supplied inert gas can be reduced. In other words, the ultraviolet irradiation device 100 according to this embodiment can reduce the amount of deformation of the external electrode 16 and optimize purging with inert gas.

[0073] 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]

[0074] 1 Barrier discharge lamp, 2 Cooling section, 2a Recess, 2c End, 2c1 Recess, 2d Recess, 4 Holder, 5 Cover, 5a Packing, 11 Discharge tube, 12 Internal electrode, 16 External electrode, 16a Curved section, 16b Mounting section, 100 Ultraviolet irradiation device

Claims

1. A light-emitting tube extending in a first direction; An internal electrode extending inside the discharge tube; An external electrode having a curved portion extending in a first direction along the outer wall of the discharge tube, and a plurality of mounting portions provided at predetermined intervals and arranged in the first direction at each of the ends of the curved portion in a second direction intersecting the first direction; The light-emitting tube and the cooling section having the curved portion and a first recess extending in the first direction; The cooling section is provided on the side where the first recess opens, and has a cover that faces the light-emitting tube across the space; A packing extending in the first direction is provided between each of the ends of the cover in the second direction and the side of the cooling section where the first recess opens; The cooling section has a plate-like shape and is provided with a plurality of holders arranged in the first direction on the side where the first recess opens; It is equipped with, Each of the plurality of holders is adjustable in the position of the curved portion relative to the light-emitting tube. An ultraviolet irradiation device capable of supplying an inert gas to the space between the light-emitting tube and the cover.

2. The end of the cooling section through which the first recess opens is provided with a plurality of second recesses facing the plurality of mounting portions of the external electrode. The ultraviolet irradiation device according to claim 1, wherein each of the plurality of second recesses is provided with the holder and the mounting portion.

3. The ultraviolet irradiation device according to claim 2, wherein the difference between the depth dimension of the second recess and the sum of the thickness of the holder and the thickness of the mounting portion is ±0.5 mm or less.

4. The ultraviolet irradiation device according to any one of claims 1 to 3, wherein the end of the cooling section through which the first recess opens is provided, and the end of the packing is provided in the third recess.

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