Ultraviolet light irradiation device

Abstract

To provide an ultraviolet light irradiation device maintaining high startability.SOLUTION: An ultraviolet light irradiation device includes: a lamp container in which discharge gas for generating excimer light is sealed; a pair of lamp electrode disposed not to be exposed to the discharge gas and applying voltage to the lamp container; a starting electrode at the same potential as one of the pair of lamp electrodes and causing discharge to generate trigger light by being disposed opposite a part at the same potential as the other electrode; a starting discharge container surrounding the tip of the starting electrode and transmitting the trigger light; and a sealing part for hermetically sealing a space at least including a space inside the starting discharge container, the sealing part being made of a material different from that of the starting discharge container.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an ultraviolet light irradiation device. [Background technology]

[0002] In an excimer lamp having a pair of external electrodes disposed on the outer surface of the lamp vessel, it is known to provide a starting electrode in order to improve the starting performance of lighting (hereinafter simply referred to as "starting performance").

[0003] For example, Patent Document 1 describes the provision of a starting electrode that is electrically connected to either a first electrode or a second electrode that applies a voltage to the lamp vessel, and that is disposed opposite the other electrode via a dielectric so as to generate a trigger light by locally discharging between the other electrode or a conductor electrically connected to the other electrode. Furthermore, the same document describes the placement of a discharge vessel so as to surround the tip of the starting electrode and the local discharge region. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-164223 Summary of the Invention [Problem to be solved by the invention]

[0005] The market demands longer life for ultraviolet light irradiation devices. To achieve longer life, it is necessary to maintain high startability over a long period of time. Therefore, the object of the present invention is to provide an ultraviolet light irradiation device that maintains high startability. [Means for solving the problem]

[0006] The ultraviolet light irradiation device according to the present invention comprises: a lamp vessel containing a discharge gas that generates excimer light; a pair of lamp electrodes arranged so as not to be exposed to the discharge gas, for applying a voltage to the lamp vessel; a starting electrode that has the same potential as one of the pair of lamp electrodes and is disposed opposite a portion that has the same potential as the other of the pair of lamp electrodes, thereby discharging and generating trigger light; a starting discharge vessel surrounding the tip of the starting electrode and transmitting the trigger light; a sealing portion that hermetically seals a space including at least the space inside the starting discharge vessel; Equipped with The sealing portion is made of a material different from that of the starting discharge vessel.

[0007] In the ultraviolet light irradiation device, the fact that the starting electrode is at the same potential as one of the pair of lamp electrodes means that the starting electrode is electrically connected to the one electrode. Also, the portion at the same potential as the other electrode may be on the surface of the other electrode, or may be on the surface of a member electrically connected to the other electrode.

[0008] Details will be explained in the "Mode for Carrying Out the Invention." Here, we will briefly explain the background and effects of the present invention. FIG. 14 is a diagram showing the periphery of a lamp electrode of a conventional ultraviolet light irradiation device. Patent Document 1 also shows a diagram similar to FIG. 14. The first electrode 9a and the second electrode 9b constituting the lamp electrodes are fixed to the inner surface of the housing (not shown) of the ultraviolet light irradiation device through screw holes 9h provided in each. A starting electrode 5 is disposed in the recess of the first electrode 9a, and the tip of the starting electrode 5 is covered by a discharge vessel 6 that surrounds the tip of the starting electrode 5 and forms a discharge space therein (hereinafter, the discharge vessel that surrounds the tip of the starting electrode 5 and forms a discharge space therein is referred to as the "starting discharge vessel"). A gap that communicates with the outside of the first electrode 9a is present between the recess of the first electrode 9a and the starting discharge vessel 6. Therefore, the air present outside the first electrode 9a penetrates into the starting discharge vessel 6 along the flow indicated by the arrow labeled F1.

[0009] As a result of intensive research by the inventors, it was found that when an ultraviolet light irradiation device having the lamp electrodes (9a, 9b), starting electrode 5, and starting discharge vessel 6 configured as shown in Figure 14 is used for a long period of time, the connection between the starting electrode 5 and the member connected to it corrodes, and the conductivity from that member to the starting electrode 5 may deteriorate. Investigation into the cause of this corrosion at the connection revealed that it was an oxidizing substance generated by the discharge generated at the tip of the starting electrode. It was found that the oxidizing substance was generated by nitrogen and water vapor contained in the atmosphere that entered along the flow indicated by the arrow labeled F1.

[0010] Therefore, in the present invention, a space including the space inside the starting discharge vessel is airtightly sealed. For example, the space surrounded by the first electrode, including at least the internal space of the starting discharge vessel, is airtightly sealed. Here, the member used to airtightly seal the space is called a sealing portion. Using the sealing portion, the space including the space inside the starting discharge vessel is airtightly sealed, preventing the inflow of air, which serves as a raw material for generating oxidizing substances, into the space. This suppresses the generation of oxidizing substances in the airtight space. As a result, corrosion of the connection between the starting electrode and the conductor connected to the starting electrode is suppressed, and conductivity from the conductor to the starting electrode 5 is maintained. Thus, trigger light can be stably emitted even when the ultraviolet light irradiation device is used for a long period of time. Furthermore, even if oxidizing substances are generated inside the starting discharge vessel, the oxidizing substances can be prevented from leaking outside the starting discharge vessel.

[0011] The sealing portion is made of a material different from that of the starting discharge vessel. For example, the starting discharge vessel is required to transmit a trigger light, whereas the sealing portion is not required to transmit the trigger light, but instead is required to provide an airtight seal to prevent gas from flowing through. In this way, the characteristics required of the starting discharge vessel and the characteristics required of the sealing portion are different, so a material that better matches the characteristics required of the sealing portion can be used for the sealing portion.

[0012] The sealing portion may airtightly seal only the space within the starting discharge vessel. When airtightly sealing only the space within the starting discharge vessel, the sealing portion may be arranged to cover the opening of the starting discharge vessel, or to close the gap between the opening of the starting discharge vessel and another member covering the opening. When the sealing portion is arranged to cover the opening of the starting discharge vessel, the starting electrode may penetrate the sealing portion. Furthermore, the sealing portion may airtightly seal not only the space within the starting discharge vessel, but also the space extending outside the starting discharge vessel. For example, the sealing portion may airtightly seal the space extending inside and outside the starting discharge vessel by closing the gap between the starting discharge vessel and the recess of the lamp electrode housed in the starting discharge vessel.

[0013] A portion of the starting discharge vessel may be located between the starting electrode and a portion of the lamp electrode that has the same potential as the other electrode. The first through fifth embodiments are examples of starting discharge vessels with such a positional relationship. The sixth embodiment discloses an embodiment in which a portion of the starting discharge vessel is not located between the starting electrode and the portion.

[0014] The sealing portion may be made of a material that has moisture absorption properties, and by absorbing water vapor within the starting discharge vessel, reduces the generation of oxidizing substances within the starting discharge vessel.

[0015] The sealing portion may be made of an epoxy or silicone adhesive.

[0016] The interior of the starting discharge vessel may contain atmospheric components including at least nitrogen, thereby allowing starting discharge to occur in the presence of atmospheric components, and generating trigger light due to atmospheric discharge.

[0017] The discharge gas may contain Kr and Cl2. When the discharge gas is a mixture of Kr and Cl2, the ultraviolet light emitted from the excimer lamp has a main emission wavelength of around 222 nm. Ultraviolet light in this wavelength range exhibits high sterilization and virus inactivation performance while minimizing its impact on the human body. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view showing the appearance of an embodiment of an ultraviolet light irradiation device. [Figure 2] 1 is a perspective view showing the appearance of an embodiment of an ultraviolet light irradiation device. [Figure 3] 1 is a perspective view showing a lamp vessel, a lamp electrode, a starting electrode, and a starting discharge vessel extracted from an ultraviolet light irradiation device. FIG. [Figure 4] This is an enlarged partial view of the vicinity of the starting electrode as viewed in the +X direction. [Figure 5] This is the optical spectrum of the trigger light generated by atmospheric discharge. [Figure 6] FIG. 10 is a partially enlarged view showing a comparative example in which there is no sealing portion that seals the starting discharge vessel. [Figure 7] 10A and 10B are diagrams illustrating modified examples of the sealing portion. [Figure 8] FIG. 4 is a partially enlarged view of a second embodiment of the ultraviolet light irradiation device. [Figure 9] FIG. 10 is a partially enlarged view of a third embodiment of the ultraviolet light irradiation device. [Figure 10] FIG. 10 is a diagram showing a fourth embodiment of the ultraviolet light irradiation device. [Figure 11] FIG. 10 is a diagram showing a fifth embodiment of the ultraviolet light irradiation device. [Figure 12] FIG. 10 is a partially enlarged view of a sixth embodiment of the ultraviolet light irradiation device. [Figure 13] FIG. 13 is a view of a part of FIG. 12 as viewed in the −X direction. [Figure 14] FIG. 1 is a perspective view showing a lamp electrode, a starting electrode, and a starting discharge vessel of a known ultraviolet light irradiation device. DETAILED DESCRIPTION OF THE INVENTION

[0019] Each embodiment of the ultraviolet light irradiation device according to the present invention will be described with reference to the drawings as appropriate. Note that the following drawings are schematic illustrations, and the dimensional ratios on the drawings do not necessarily match the actual dimensional ratios. Furthermore, the dimensional ratios between the drawings do not necessarily match.

[0020] In the following, each drawing will be described with reference to the XYZ coordinate system as appropriate. In the XYZ coordinate system, the direction in which a ray on the optical axis of emitted ultraviolet light travels is defined as the +X direction, and the plane perpendicular to the X direction is defined as the YZ plane. In this specification, when a direction is expressed and a positive or negative direction is distinguished, it is described with a positive or negative sign, such as "+X direction" or "-X direction." When a direction is expressed without distinguishing between positive and negative directions, it is simply described as "X direction." In other words, in this specification, when simply referring to the "X direction," it includes both the "+X direction" and the "-X direction." The same applies to the Y direction and the Z direction.

[0021] First Embodiment [Outline of UV light irradiation equipment] 1 and 2 are perspective views showing the appearance of an embodiment of an ultraviolet light irradiation device according to the present invention. Fig. 1 is a view of the ultraviolet light irradiation device 10 as seen from the light extraction unit 4 side, and Fig. 2 is a view as seen from the opposite side to the light extraction unit 4 side.

[0022] The ultraviolet light irradiation device 10 of this embodiment includes an excimer lamp that emits ultraviolet light. The ultraviolet light irradiation device 10 includes a lamp vessel 3 (see FIG. 2), a housing 2 that houses the lamp vessel 3, and a light extraction unit 4 that extracts the ultraviolet light emitted from the lamp vessel 3 to the outside of the housing 2 in the +X direction. In FIGS. 1 and 2, the arrow labeled L1 indicates the optical axis of the ultraviolet light emitted from the light extraction unit 4 and the traveling direction of the light ray on the optical axis. The longitudinal direction of the tube axis of the lamp vessel 3 extends along the Y direction.

[0023] In this embodiment, the housing 2 is composed of a first frame 2a having an opening in the center that is used as the light extraction portion 4, and a second frame 2b that has no opening. The second frame 2b and the first frame 2a are fitted together to form an internal space surrounded by the housing 2. In this internal space, four lamp vessels 3 and a pair of lamp electrodes (9a, 9b) that supply power to the lamp vessels 3 are arranged.

[0024] As shown in FIG. 2, the pair of lamp electrodes (9a, 9b) are fixed to a surface of the second frame 2b that contacts the internal space. Two connection terminals (8a, 8b) are provided on a surface of the second frame 2b that contacts the outside. The two connection terminals (8a, 8b) are electrically connected to the pair of lamp electrodes (9a, 9b) across the second frame 2b. Power supply lines (7a, 7b) that supply power from an external power source (not shown) are connected to the two connection terminals (8a, 8b), respectively. The pair of lamp electrodes (9a, 9b) are made of a conductive material (e.g., aluminum, aluminum alloy, stainless steel, etc.).

[0025] FIG. 3 is a perspective view showing four lamp vessels (3a, 3b, 3c, 3d) spaced apart in the Z direction, a pair of lamp electrodes (9a, 9b) spaced apart in the Y direction, a starting electrode 5, and a starting discharge vessel 6 extracted from the ultraviolet light irradiation device 10.

[0026] The pair of lamp electrodes (9a, 9b) is composed of a first electrode 9a and a second electrode 9b. The first electrode 9a and the second electrode 9b have the same shape. A plurality of recesses are formed on the +X side surfaces of the lamp electrodes (9a, 9b). Each recess has a substantially V-shaped groove extending in the Y direction. The lamp capsules (3a, 3b, 3c, 3d) are arranged spaced apart from each other in the Z direction so as to be sandwiched between the recesses of the pair of lamp electrodes (9a, 9b). Each of the pair of lamp electrodes (9a, 9b) is in contact with the outer surface of the lamp capsule (3a, 3b, 3c, 3d).

[0027] A discharge gas that generates excimer light is sealed inside the lamp vessel 3. The pair of lamp electrodes (9a, 9b) are located outside the lamp vessel 3, and the discharge gas is located inside the lamp vessel 3, so the pair of lamp electrodes (9a, 9b) are not exposed to the discharge gas. When a high-frequency AC voltage of, for example, about 1 kHz to 5 MHz is applied between the pair of lamp electrodes (9a, 9b), a dielectric barrier discharge occurs inside the lamp vessel 3, and atoms constituting the gas species are excited or ionized to enter an excimer state, and then emit excimer light when they transition to the ground state.

[0028] In this embodiment, the discharge gas is a mixed gas containing Kr and Cl2, and the emitted excimer light is ultraviolet light with a main emission wavelength of around 222 nm. Ultraviolet light in this wavelength band is known to exhibit high sterilization and virus inactivation performance while minimizing its impact on the human body, and the ultraviolet light irradiation device 10 is used in sterilization devices, virus inactivation devices, etc. However, the gas species of the discharge gas are not limited to those described above. The gas species of the discharge gas may be one or more rare gases such as argon (Ar), krypton (Kr), xenon (Xe), etc., or a mixed gas of the rare gas with a halogen gas such as fluorine (F), chlorine (Cl), iodine (I), or bromine (Br).

[0029] As another example of a combination of gas species, a mixed gas of krypton (Kr), chlorine (Cl), and argon (Ar) can be used as the discharge gas. In this case, krypton and chlorine function as luminous gases, and argon functions as a buffer gas. Furthermore, one or more rare gases selected from argon (Ar), neon (Ne), and helium (He) can be used as the buffer gas.

[0030] [Starting electrode] As shown in FIG. 3, the ultraviolet light irradiation device 10 includes a starting electrode 5. The starting electrode 5 assists in starting the illumination of the excimer lamp. The details of the starting electrode 5 will be described with reference to FIG. 4. FIG. 4 is an enlarged view of the ultraviolet light irradiation device 10, looking in the +X direction, near the starting electrode 5. The starting electrode 5 extends generally in the Y direction. The starting electrode 5 of this embodiment has a spiral proximal portion 5a and a distal portion 5b that is less spiral and has a shape that is relatively closer to a rod than the proximal portion 5a. The spiral proximal portion 5a has elasticity in the Y direction. The distal portion 5b is relatively straighter than the proximal portion 5a, but has a slight bend.

[0031] The first electrode 9a has a recess in its side surface 9as (see FIG. 4), and the proximal portion 5a of the starting electrode 5 is disposed in the recess. The proximal portion 5a contacts the bottom of the recess, thereby electrically connecting the proximal portion 5a to the first electrode 9a. The distal portion 5b of the starting electrode 5 extends to the vicinity of the side surface 9bs of the second electrode 9b, which faces the side surface 9as of the first electrode 9a. A corona discharge is generated between the tip 5c of the distal portion 5b and the second electrode 9b.

[0032] The shape of the starting electrode 5 is not limited to the structure of this embodiment. The starting electrode 5 may have an overall columnar, rod-like, thin plate-like, or other shape. Furthermore, the shape of the distal portion 5b of the starting electrode 5 is not limited to a rod-like shape and may be a thin plate-like shape, but it is preferable that the tip 5c of the distal portion 5b be pointed. This concentrates the electric field at the tip 5c of the starting electrode 5, making it easier for discharge to occur at the tip 5c of the starting electrode 5.

[0033] The starting electrode 5 is made of a conductive material. It is preferable that the starting electrode 5 is made of a metal material that is highly corrosion-resistant to oxidizing substances. For example, the starting electrode 5 is preferably made of titanium, aluminum, molybdenum, or stainless steel, and more preferably made of gold, platinum, or tungsten.

[0034] [Starting discharge vessel] As shown in FIG. 4 , the starting discharge vessel 6 is disposed so as to surround the tip 5c of the starting electrode 5. The starting discharge vessel 6 has a cylindrical shape with a cylindrical portion and a bottom that closes one end of the cylindrical portion. The tip 5c of the starting electrode 5 is pressed against the bottom of the starting discharge vessel 6 by the elastic force of the proximal portion 5a. The starting discharge vessel of this embodiment has a cylindrical portion, and the boundary between the cylindrical portion and the bottom is connected so as to be rounded. However, the starting discharge vessel is not limited to a cylindrical portion and may be a rectangular or other cylindrical portion. Furthermore, the bottom is not limited to a flat shape and may be hemispherical or other shapes. The starting discharge vessel 6 is pressed against the second electrode 9b. The starting discharge vessel 6 functions as a dielectric between the tip 5c of the starting electrode and the second electrode 9b. The starting electrode 5 and the starting discharge vessel 6 do not necessarily need to be in contact with each other; they may be spaced apart enough to allow discharge.

[0035] The starting discharge vessel 6 is preferably made of a material that has high mechanical strength, insulating properties, and functions as a dielectric. For example, the starting discharge vessel 6 is preferably made of quartz glass, a ceramic material such as alumina, or a resin material such as PTFE. Furthermore, the starting discharge vessel 6 is preferably made of a material that has high transmittance for ultraviolet light (trigger light, described below); for example, it is more preferable to use quartz glass for the starting discharge vessel 6.

[0036] Regarding the excimer emission that occurs within the lamp vessel 3, especially when halogen gas is sealed within the lamp vessel 3, the halogen gas, which has a high electron affinity, gradually absorbs electrons. This makes it difficult for current to flow through the discharge gas (electrons are less likely to move), especially if the lamp is left unlit for a while. As a result, starting the lamp becomes difficult. Therefore, trigger light L2 is generated using the starting electrode 5, and the generated trigger light L2 is incident on the lamp vessel 3, imparting light energy to the discharge gas within the lamp vessel 3, inducing excimer excitation within the lamp vessel 3 and generating an excimer discharge.

[0037] Air (mainly containing nitrogen gas) is present around the tip 5c of the starting electrode 5. When the ultraviolet light irradiation device 10 is operated, a voltage is applied not only to the pair of lamp electrodes (9a, 9b), but also between the starting electrode 5 and the second electrode 9b. Because the distance between the starting electrode 5 and the second electrode 9b is smaller than the distance between the pair of lamp electrodes (9a, 9b), a breakdown occurs at a lower voltage than within the lamp vessel 3, generating a corona discharge in the air. This discharge generates trigger light L2.

[0038] FIG. 5 shows the optical spectrum of trigger light emitted by atmospheric corona discharge (hereinafter, "atmospheric corona discharge" may be referred to as "atmospheric discharge"). The trigger light has a continuous spectrum with many peak wavelengths, for example, a peak wavelength between 226 nm and 227 nm. On the other hand, when the discharge gas sealed in the lamp vessel 3 contains krypton (Kr) and chlorine (Cl), the peak wavelength in the optical spectrum of the excimer light emitted from the lamp vessel 3 is 222 nm. The peak wavelength of the trigger light is close to the peak wavelength of the excimer light. Therefore, the starting electrode 5, which generates an atmospheric discharge, easily induces the excitation of KrCl excimer light within the lamp vessel 3. When the trigger light generated by the starting electrode 5 is incident on the lamp vessel 3, the energy of the trigger light initiates excimer light emission within the lamp vessel 3 within a short time (for example, within 2 seconds), and the excimer lamp (ultraviolet light irradiation device 10) lights up.

[0039] Note that even after the excimer lamp is lit, voltage continues to be applied to the tip 5c of the starting electrode 5, so the trigger light may continue to be emitted at the tip 5c. Even in this case, the power used at the tip 5c of the starting electrode 5 is very small, so the reduction in the illuminance of the excimer lamp due to the power lost to emitting the trigger light is usually not a problem. Furthermore, after the excimer lamp is lit, the discharge inside the lamp vessel 3 becomes dominant, which acts to suppress atmospheric discharge at the starting electrode 5, so the effect of the trigger light on the excimer lamp is smaller.

[0040] Although Figure 5 shows only the wavelength range of 200 nm to 320 nm of the light spectrum generated by atmospheric discharge, it also has emission bands in other ultraviolet wavelength ranges and has multiple emission peaks. Therefore, the trigger light generated by atmospheric discharge is useful for devices other than KrCl excimer lamps. For example, the peak wavelength of a XeCl excimer lamp is 308 nm, but this trigger light is also effective for XeCl excimer lamps.

[0041] The reason for using the starting discharge vessel 6, which is positioned to surround the tip 5c of the starting electrode 5, as a dielectric is as follows. The atmospheric discharge occurring near the tip 5c of the starting electrode 5 generates nitrogen oxides (hereinafter sometimes referred to as "NOx"), such as nitric oxide and nitrogen dioxide, from N2 and O2 in the atmosphere. Furthermore, the atmosphere contains water vapor (H2O), and NOx can react with the atmospheric H2O to generate nitric acid gas (HNO3). Nitric acid gas is an oxidizing substance. NOx and oxidizing substances may have undesirable effects on the ultraviolet light irradiation device, surrounding equipment, people, and the environment.

[0042] [Sealing part of starting discharge vessel] Fig. 6 is a further enlarged view of the area around the starting electrode 5, showing a comparative configuration in which there is no sealing portion that seals the starting discharge vessel 6. The comparative configuration in Fig. 6 is an enlarged view of the conventional configuration shown in Fig. 14. First, with reference to the comparative configuration, we will explain the problems that arise when there is no sealing portion that seals the starting discharge vessel 6, and then explain why the problems can be solved by the sealing portion that seals the starting discharge vessel 6.

[0043] As shown in Figure 6, the starting discharge vessel 6 is inserted into a recess in the first electrode 9a. A gap exists between the outer wall of the starting discharge vessel 6 and the inner wall of the recess. This gap allows communication between the recess of the first electrode 9a and the interior of the starting discharge vessel 6. Therefore, the air outside the first electrode 9a penetrates into the interior of the starting discharge vessel 6 along the flow indicated by the arrow labeled F1. As mentioned above, the air contains nitrogen and water vapor, which can generate nitric acid gas (HNO3), an oxidizing substance. Although the amount of nitric acid gas generated over a short period of time is small, the impact of nitric acid gas generated over a long period of time has become significant as lamp life has increased. Corrosion by nitric acid gas is particularly problematic at the connection 11 between the first electrode 9a, which is a conductor connected to the starting electrode 5, and the starting electrode 5 (the area surrounded by the dashed-dotted circle in Figure 6). Oxidizing substances 13 migrate to the connection 11, adhere to the connection 11, and cause corrosion. It was found that when the ultraviolet light irradiation device is turned on for a long period of time, electrical conduction to the starting electrode 5 is hindered due to the progression of corrosion.

[0044] Corrosion will now be described. When the oxidizing substance 13 is nitric acid gas and the member to be corroded is aluminum, the nitric acid gas comes into contact with the aluminum and undergoes a chemical reaction to produce nitrate (for example, Al(NO3)3). The nitrate is in powder form and is emitted from the first electrode 9a. The first electrode 9a is scraped off. In this way, the connection 11 between the first electrode 9a and the starting electrode 5 is scraped off, resulting in poor electrical continuity. Furthermore, the connection 11 is subject to a load when the starting electrode 5 is pressed against it, making it prone to breakage. If the connection 11 breaks, the starting electrode 5 will no longer function and the trigger light will not be emitted.

[0045] Therefore, a sealing portion is formed in the gap so that the space including the inside of the starting discharge vessel 6 is airtightly sealed. This prevents moisture-containing air from penetrating into the starting discharge vessel 6. This prevents oxidizing substances from being continuously generated inside the starting discharge vessel 6.

[0046] In FIG. 4 , a sealing member 7 is attached to the open end of the starting discharge vessel 6, airtightly sealing only the space within the starting discharge vessel 6. The sealing member 7 is pierced by the starting electrode 5, airtightly sealing the interior of the starting discharge vessel 6 from the outside. This prevents oxidizing substances from coming into contact with the connection 11, even if they are generated by the atmosphere present inside the starting discharge vessel 6 during manufacturing. This prevents the oxidizing substances from coming into contact with the connection 11, thereby suppressing corrosion at the connection 11. In other words, the placement of the sealing member 7 shown in FIG. 4 not only prevents the generation of oxidizing substances by blocking the atmosphere, but also further suppresses corrosion by separating the space including the area susceptible to corrosion by oxidizing substances from the space within the starting discharge vessel where the oxidizing substances are generated by the sealing member 7. Furthermore, even if oxidizing substances are generated inside the starting discharge vessel 6, the oxidizing substances are prevented from leaking outside the starting discharge vessel 6. Although oxidizing substances may adhere to the distal portion 5b of the starting electrode 5, corrosion at the distal portion 5b has little effect on electrical continuity. If corrosion at the distal portion 5b is a problem, highly corrosion resistant materials such as tungsten, gold and platinum may be used for the distal portion 5b (starting electrode 5).

[0047] There are various methods for forming the sealed portion of the starting discharge vessel 6. When the starting discharge vessel 6 is made of a glass-like material, one method is to heat-form a portion of the starting discharge vessel 6 and close the starting discharge vessel 6 to form the sealed portion 7. In this method, the sealed portion 7 is made of the same material as the starting discharge vessel 6. However, in this embodiment, the method of heat-forming a portion of the starting discharge vessel 6 and closing the starting discharge vessel 6 to form the sealed portion 7 is not adopted.

[0048] When forming the sealed portion 7 by heat-molding a portion of the starting discharge vessel 6 and closing the starting discharge vessel 6, the gas inside the starting discharge vessel 6 is exposed to high temperatures during the heat-molding process. After closing, the space inside the starting discharge vessel 6 becomes a reduced-pressure space with a pressure lower than atmospheric pressure. If the space inside the starting discharge vessel 6 is a reduced-pressure space, excessive discharge occurs at the starting electrode 5, making the starting electrode 5 more susceptible to wear. It is preferable that the space inside the starting discharge vessel 6 be a space with a gas pressure close to atmospheric pressure. For this reason, this embodiment employs a method of forming the sealed portion 7 without heat-molding a portion of the starting discharge vessel 6.

[0049] In this embodiment, a sealing portion 7 is used that is separate from the starting discharge vessel 6. In this embodiment, a different material is used for the sealing portion 7 than for the starting discharge vessel 6. Since the characteristics required for the starting discharge vessel 6 and the sealing portion 7 are different, a material that better matches the characteristics required for the sealing portion 7 can be used for the sealing portion 7. Note that a space with a gas pressure at about atmospheric pressure refers to a space within a range of ±30% of the pressure (unit: Pa) of the environment in which the ultraviolet light irradiation device is placed.

[0050] Possible materials for the sealing portion 7 include ceramic materials such as quartz glass and alumina, resin materials such as silicone, epoxy, acrylic, and urethane, and rubber materials. Because the sealing portion 7 penetrates the starting electrode 5, there will inevitably be a portion where the sealing portion 7 comes into contact with the starting electrode 5. However, the thermal expansion coefficients of the sealing portion 7 and the starting electrode 5 are different. Therefore, it is preferable to use a highly elastic material for the sealing portion 7 so that the sealing portion 7 can easily adhere to the starting electrode 5 even when the temperature changes. Examples of highly elastic materials include resin and rubber. Furthermore, because ozone (O3) is generated from oxygen molecules in the atmosphere by discharge near the tip 5c of the starting electrode 5, it is preferable to use a material that is resistant to deterioration by ozone, such as a resin.

[0051] The gap between the starting discharge vessel 6 and the sealing portion 7 may be sealed with an adhesive. Furthermore, since the opening diameter of the starting discharge vessel 6 is small, the sealing portion 7 itself may be made of an adhesive. If the sealing portion 7 itself is made of an adhesive, it is preferable to use an epoxy-based or silicone-based adhesive, which can adhere well to the two materials, the starting discharge vessel 6 and the starting electrode 5. In this embodiment, the use of an adhesive is optional and not essential. The sealing portion 7 may be engaged with the starting discharge vessel 6. For example, a recess or protrusion may be formed on the outer wall surface of the starting discharge vessel 6 to prevent the sealing portion 7 from shifting.

[0052] It is preferable that the sealing portion 7 be made of a moisture-absorbing material, as this reduces the moisture that is essential for generating nitric acid from within the starting discharge vessel 6. The moisture-absorbing material is particularly preferably a material that hardens through a condensation reaction (for example, a moisture-curing resin). When an adhesive is used for the sealing portion 7, using a moisture-curing adhesive can achieve two effects at once: hardening the adhesive and removing moisture from within the starting discharge vessel. Furthermore, a moisture-absorbing material may be placed inside the starting discharge vessel 6, separate from the sealing portion 7.

[0053] The sealing portion 7 may be made of a thermosetting material (typically a thermosetting adhesive). It is preferable to use a material that thermosets at 110°C or below. If the temperature is 110°C or below, the above-mentioned disadvantage of the interior of the starting discharge vessel 6 becoming a reduced pressure space does not occur.

[0054] When attaching the sealing part 7 to the starting discharge vessel 6, the sealing part 7 may be attached with nitrogen gas sealed inside the starting discharge vessel 6. By eliminating or reducing the oxygen and water vapor inside the starting discharge vessel 6, it is possible to prevent the generation of nitric acid gas or reduce the amount of nitric acid gas generated.

[0055] [Sealing deformation] FIG. 7 shows a modified embodiment of the sealing portion 7 described above. In the embodiment shown in FIG. 7, the sealing portion 7 is not attached to the open end of the starting discharge vessel 6, but is arranged so as to close the gap between the outer wall of the starting discharge vessel 6 and the inner wall of the recess in the first electrode 9a. The sealing portion 7 may also be an annular element that surrounds the periphery of the starting discharge vessel 6. Even in the embodiment shown in FIG. 7, the space including the interior of the starting discharge vessel 6 is airtightly sealed, preventing the inflow of moisture-containing air from the outside.

[0056] Second Embodiment A second embodiment of the ultraviolet light irradiation device will be described with reference to Fig. 8. The second embodiment can be implemented in the same manner as the first embodiment and the modified embodiment of the first embodiment except for the details described below. The same applies to the third and subsequent embodiments.

[0057] 8 is an enlarged view of the periphery of starting electrode 5 in an ultraviolet light irradiation device of the second embodiment. This embodiment has starting electrode 5 connected to first electrode 9a and starting electrode 15 connected to second electrode 9b. Tip 5c of starting electrode 5 and tip 15c of starting electrode 15 are arranged opposite each other. Each starting electrode (5, 15) has the same potential as one of the pair of lamp electrodes, and is characterized in that it is arranged opposite a portion of the other electrode that has the same potential as the other electrode so as to discharge and generate trigger light L2.

[0058] Starting discharge vessel 6 is interposed between tip 5c of starting electrode 5 and tip 15c of starting electrode 15, surrounding both tips (5c, 15c). Starting discharge vessel 6 is partitioned into a first space surrounding tip 5c of starting electrode 5 and a second space surrounding tip 15c of starting electrode 15. Sealing portions (7, 17) are penetrated by the respective starting electrodes (5, 15) and airtightly seal the respective spaces of starting discharge vessel 6. Connection portion 11 between starting electrode 5 and first electrode 9a is located outside starting discharge vessel 6.

[0059] Third Embodiment A third embodiment of the ultraviolet light irradiation device will be described with reference to Figure 9. Figure 9 is an enlarged view of the periphery of the starting electrode 5 in the ultraviolet light irradiation device of the third embodiment. In this embodiment, the starting electrode 5 connected to the first electrode 9a is in the form of a coil made of a wound, elongated conductor. The +Y side ends of the multiple coils form the tips 5c of the starting electrodes 5, thereby obtaining a wide discharge area. In this embodiment as well, the coil-shaped starting electrode 5 is surrounded by the starting discharge vessel 6 and the sealed portion 7. The starting electrode 5 penetrates the sealed portion 7, and the connection portion 11 between the starting electrode 5 and the first electrode 9a is located outside the starting discharge vessel 6.

[0060] <Fourth embodiment> 10 shows a fourth embodiment of an ultraviolet light irradiation device. An ultraviolet light irradiation device 40 has a lamp vessel 3 filled with a discharge gas 3G. The lamp vessel 3 is elongated in the Y direction, and its cross section along the XZ plane is a flat, approximately rectangular shape. A first electrode 9a and a second electrode 9b are provided on a pair of flat outer surfaces along the YZ plane of the lamp vessel 3, respectively. A high voltage is applied to the first electrode 9a and the second electrode 9b.

[0061] In this embodiment, the first electrode 9a is formed in a lattice pattern, and excimer light L1 can be extracted from the areas without the lattice. Although the lattice shape of the first electrode 9a cannot be seen in FIG. 10, the lattice shape can be seen when the first electrode 9a is viewed in the -X direction. The shape of the first electrode 9a is not particularly limited as long as it allows light to be extracted. The second electrode 9b is an electrode that extends over a surface along the YZ plane. The second electrode 9b may have any shape other than a surface. Since the first electrode 9a and the second electrode 9b are located on the outer surface of the lamp vessel 3, the first electrode 9a and the second electrode 9b are not exposed to the discharge gas 3G.

[0062] The ultraviolet light irradiation device 10 includes a starting electrode 5 electrically connected to the second electrode 9b and at the same potential as the second electrode 9b, and a conductive member 12 electrically connected to the first electrode 9a and at the same potential as the first electrode 9a. The starting electrode 5 is positioned opposite the conductive member 12. The conductive member 12 has a flat portion facing the starting electrode 5. A starting discharge vessel 6 is interposed between the starting electrode 5 and the conductive member 12. The starting discharge vessel 6 surrounds the tip of the starting electrode 5. An atmospheric discharge generated at the tip of the starting electrode 5 emits trigger light L2. The trigger light L2 passes through the starting discharge vessel 6. The starting discharge vessel 6 is hermetically sealed by a sealing member 7. A connection portion 11 between the starting electrode 5 and the conductor connected to the starting electrode 5 is located outside the starting discharge vessel 6. The sealing portion 7 has a through-hole through which the starting electrode 5 passes, and the starting electrode 5 is inserted, but the sealing portion 7 and the starting electrode 5 are in close contact within the through-hole, maintaining an airtight state. This prevents the air outside the starting discharge vessel 6 from flowing into the starting discharge vessel 6. Thus, even if oxidizing substances are generated inside the starting discharge vessel 6, they can be prevented from leaking out of the starting discharge vessel 6.

[0063] In this embodiment, the starting electrode 5 is disposed outside the lamp vessel 3 in the Y direction of the lamp tube axis, but the starting electrode 5 does not have to be located in this position. However, it is preferable that the tip 5c of the starting electrode 5 is close to the lamp vessel 3, and the distance between the tip 5c of the starting electrode 5 and the lamp vessel 3 is preferably less than 30 mm, more preferably 20 mm or less, and even more preferably 15 mm or less.

[0064] Fifth Embodiment 11 shows a fifth embodiment of an ultraviolet light irradiation device. An ultraviolet light irradiation device 50 has a lamp vessel 3 in which a discharge gas 3G is sealed. The lamp vessel 3 of this embodiment has a double-tube structure that is long in the Y direction. The lamp vessel 3 includes an inner tube 3i and an outer tube 3o that surrounds the inner tube 3i. The Y-direction ends of the inner tube 3i and the outer tube 3o are sealed, forming a closed space between the inner tube 3i and the outer tube 3o. A discharge gas 3G is sealed in this closed space.

[0065] A first electrode 9a is provided on the outer peripheral wall of the outer tube 3o. The first electrode 9a is formed in a grid pattern, and excimer light L1 can be extracted from the areas where there is no grid. A second electrode 9b is provided on the inner peripheral wall of the inner tube 3i. The second electrode 9b is an electrode that extends all along the inner peripheral surface. A high voltage is applied to the first electrode 9a and the second electrode 9b. The first electrode 9a and the second electrode 9b are not exposed to the discharge gas 3G.

[0066] The ultraviolet light irradiation device 50 includes a starting electrode 5 electrically connected to the second electrode 9b and at the same potential as the second electrode 9b, and a conductive member 12 electrically connected to the first electrode 9a and at the same potential as the first electrode 9a. The starting electrode 5 is positioned opposite the conductive member 12. The starting discharge vessel 6 is hermetically sealed by a sealing member 7. Portions susceptible to corrosion by oxidizing substances, such as the connection 11 between the starting electrode 5 and the conductor connected to the starting electrode 5, are located outside the starting discharge vessel 6. In this embodiment, the starting electrode 5 is located inside the inner tube 3i, but the starting electrode 5 does not have to be located in this position. However, as mentioned above, it is preferable that the tip of the starting electrode 5 be close to the lamp vessel 3.

[0067] Sixth Embodiment A sixth embodiment of an ultraviolet light irradiation device will be described with reference to Figures 12 and 13. Figure 12 is an enlarged view of the periphery of the starting electrode 5 in an ultraviolet light irradiation device 60 of the sixth embodiment. Figure 13 is a view of the ultraviolet light irradiation device 60 of Figure 12 excluding the lamp vessel 3 and electrodes (9a, 9b), viewed in the -X direction from the electrode pads (69a, 69b).

[0068] The ultraviolet light irradiation device 60 includes a lamp vessel 3 filled with a discharge gas 3G, and two electrodes (first electrode 9a and second electrode 9b) arranged spaced apart from each other on the outer surface of the lamp vessel 3 in the −X direction.

[0069] The first electrode 9a is electrically connected to the starting electrode 5 via an electrode pad 69a and a conductive path. The first electrode 9a and the starting electrode 5 are at the same potential. The second electrode 9b is electrically connected to the conductive member 12 via an electrode pad 69b and a conductive path. The second electrode 9b and the conductive member 12 are at the same potential. The pair of electrode pads (69a, 69b) are disposed on a substrate. The starting electrode 5 is exposed from the substrate 65. The conductive member 12 is embedded inside the substrate 65. The substrate 65 is an insulator. The space between the starting electrode 5 and the conductive member 12 acts as a dielectric.

[0070] The starting electrode 5 in this embodiment is a creeping discharge type. A creeping discharge occurs in region a1 in Figure 12, generating trigger light L2. The tip of the starting electrode 5 is surrounded by starting discharge vessel 6, but starting discharge vessel 6 is not located between starting electrode 5 and conductive member 12. The end of starting discharge vessel 6 is airtightly fixed to substrate 65 by sealing portion 7, which is an adhesive. At this time, adhesive is applied so as to cover starting electrode 5, and the end of starting discharge vessel 6 is joined to the applied adhesive. This allows sealing portion 7, which is an adhesive, to airtightly seal starting discharge vessel 6. Parts that are susceptible to corrosion by oxidizing substances, such as starting electrode 5 and electrode pads (69a, 69b) connected via a conductor leading to starting electrode 5, are located outside starting discharge vessel 6.

[0071] Although the embodiments and modifications of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments and modifications. The scope of the present invention is defined not only by the description of the above-mentioned embodiments and modifications but also by the claims, and further includes all modifications within the meaning and scope of the claims.

[0072] The structures employed in the above-described embodiments and modifications can be employed in any other embodiments and modifications. The specific configurations of the components are not limited to the above-described embodiments and modifications, and various modifications are possible within the scope of the present invention. [Example]

[0073] An experiment was conducted to investigate the life extension effect of providing an ultraviolet light irradiation device with a sealing portion 7 that airtightly seals the starting discharge vessel 6. The starting electrode 5, starting discharge vessel 6, and sealing portion 7 of the ultraviolet light irradiation device described in the first embodiment were used. Samples with and without a sealing portion were prepared, and an experiment was conducted to measure the starting time after a predetermined lighting time had passed. When measuring the starting time, all samples were left in the dark for 50 hours to prevent the starting performance from being affected by the ambient light from the ultraviolet light irradiation device. The experimental conditions are shown below.

[0074] [Lamp container] Material: Quartz glass, Outer diameter: 6 mm, Total length: 60 mm [Discharge gas] Gas pressure: 19 kPa, Gas type: Cl2 and Kr mixed gas [First electrode and second electrode] Material: Aluminum, Length: 60 mm, Distance between electrodes: 6 mm [External power supply] Voltage: 5kV, Frequency: 100kHz [Starting electrode] Material: tungsten, shape: as shown in Figure 4, electrode diameter: 0.25 mm Length = 17 mm [Starting discharge vessel] Outer diameter = 4mm, inner diameter = 2.4mm, length = 13mm [Sealing part] Material: Silicone adhesive

[0075] The experimental results are shown in Table 1. [Table 1]

[0076] There was no difference in start-up time between the sealed and unsealed samples until the cumulative lighting time reached 5,000 hours. After 6,000 hours of lighting, the unsealed sample began to experience a delay in starting. After 8,000 hours of lighting, the excimer lamp in the unsealed sample did not light even after 60 seconds. In contrast, the sealed sample lit up without any delay, even after 8,000 hours of lighting.

[0077] When a sample without a sealed portion with an accumulated lighting time of 8,000 hours was disassembled, it was found that powdery nitrate had adhered to the connection between starting electrode 5 and first electrode 9a connected to starting electrode 5, causing poor conductivity. When a sample with a sealed portion with an accumulated lighting time of 8,000 hours was disassembled, no dust was found at the connection between starting electrode 5 and first electrode 9a connected to starting electrode 5. [Explanation of symbols]

[0078] 2: Housing 2a: First frame (constituting the housing) 2b: Second frame (constituting the housing) 3: Lamp container 3G: Discharge gas 3i: Inner tube 3o: Outer tube 4: Light extraction section 5,15: Starting electrode 5a: Proximal part (of the starting electrode) 5b: Distal part (of starting electrode) 5c, 15c: Tip (of starting electrode) 6: Starting discharge vessel 7: Sealing part 9a: First electrode (forming a pair of lamp electrodes) 9b: Second electrode (constituting a pair of lamp electrodes) 10,40,50,60: Ultraviolet light irradiation device 11: Connection part 12: Conductive material 13: Oxidizing substances 65: Circuit board 69a, 69b: electrode pads L1: Excimer light L2: Trigger light

Claims

1. a lamp vessel containing a discharge gas that generates excimer light; a pair of lamp electrodes arranged so as not to be exposed to the discharge gas, for applying a voltage to the lamp vessel; a starting electrode that has the same potential as one of the pair of lamp electrodes and is disposed opposite a portion that has the same potential as the other of the pair of lamp electrodes, thereby discharging and generating trigger light; a starting discharge vessel surrounding the tip of the starting electrode and transmitting the trigger light; a sealing portion that hermetically seals a space including at least the space inside the starting discharge vessel; Equipped with The ultraviolet light irradiation device is characterized in that the sealing portion is made of a material different from that of the starting discharge vessel.

2. 2. The ultraviolet light irradiation device according to claim 1, wherein the sealing portion hermetically seals only the space within the starting discharge vessel.

3. 2. The ultraviolet light irradiation device according to claim 1, wherein a part of said starting discharge vessel is located between said starting electrode and a part having the same potential as said other electrode.

4. 2. The ultraviolet light irradiation device according to claim 1, wherein the sealing portion is made of a material having a moisture absorbing property.

5. 2. The ultraviolet light irradiation device according to claim 1, wherein the sealing portion is made of an epoxy-based or silicone-based adhesive.

6. 6. The ultraviolet light irradiation device according to claim 1, wherein atmospheric components are present inside the starting discharge vessel.

7. The discharge gas is Kr and Cl ２ The ultraviolet light irradiation device according to any one of claims 1 to 5, comprising:

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