UV generator

Abstract

To improve starting performance in an ultraviolet light generator that uses an excimer lamp as an ultraviolet light source.SOLUTION: An ultraviolet light generator includes an excimer lamp having a discharge vessel filled with discharge gas, a first electrode body and a second electrode body arranged so as not to be exposed to discharge gas, and a first conductor electrically connected to one of the first electrode body and the second electrode body. The first conductor is arranged to face the other electrode body or a second conductor electrically connected to the other electrode body via a dielectric member, and the first conductor generates an atmospheric discharge around the first conductor.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to an ultraviolet light generating device, and more particularly to an ultraviolet light generating device that uses an excimer lamp as an ultraviolet light source. [Background technology]

[0002] Conventionally, excimer lamps have been known in which a pair of external electrodes are arranged facing each other on the outer surface of a discharge vessel, and it is known to provide a first conductor made of a conductive material on the inner surface of the discharge vessel in order to improve starting performance (for example, Patent Document 1 below).

[0003] In Patent Document 1, the external electrode is provided with a branched electrode consisting of a root portion extending from an end in the tube axis direction of the external electrode along the tube axis direction of the discharge vessel and a branch portion extending from the tip of the root portion in the width direction of the discharge vessel, and the first conductor is arranged so as to overlap with the tip of the branch portion of the branched electrode of the external electrode, with the discharge vessel interposed therebetween. With this configuration, when the excimer lamp is started, a high-frequency current applied to one external electrode is in a kind of capacitor-coupled state, and the high-frequency current flows to the other external electrode through the dielectric wall that makes up the discharge vessel, making it easier to generate a discharge and improving starting performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-190676 Summary of the Invention [Problem to be solved by the invention]

[0005] Excimer lamps can emit light with different emission wavelengths depending on the type of luminous gas enclosed within. However, depending on the type of luminous gas enclosed within, it may be difficult to adopt the configuration described in Patent Document 1. For example, when a rare gas and a halogen gas are enclosed within the discharge vessel, the halogen gas is highly reactive and is absorbed by conductive materials, making it difficult to form a first conductor within the discharge vessel. Therefore, the technology described in Patent Document 1 is not very versatile as a means of improving the starting performance of excimer lamps.

[0006] In view of the above problems, an object of the present invention is to improve the start-up performance of an ultraviolet light generating device that uses an excimer lamp as an ultraviolet light source. [Means for solving the problem]

[0007] The ultraviolet light generating device according to the present invention comprises: an excimer lamp having a discharge vessel in which a discharge gas is sealed; a first electrode body and a second electrode body arranged so as not to be exposed to the discharge gas; a first conductor electrically connected to either the first electrode body or the second electrode body, the first conductor is disposed opposite to the other electrode body or a second conductor electrically connected to the other electrode body via a dielectric member; The first conductor generates an atmospheric discharge around the first conductor.

[0008] With this configuration, an atmospheric discharge can be generated around the first conductor by applying a voltage to the first electrode body and the second electrode body. Light emitted by this atmospheric discharge induces excitation of excimers within the discharge vessel of the excimer lamp, improving the starting performance of the excimer lamp. Note that atmospheric discharge here refers to a discharge phenomenon that occurs in the atmosphere, specifically, corona discharge, creeping discharge, etc., that occur in the atmosphere. Furthermore, the first conductor is disposed opposite the other electrode body or the second conductor electrically connected to the other electrode body via a dielectric member, thereby generating atmospheric discharge. More specifically, atmospheric discharge occurs from the tip of the first conductor, where electric field concentration is likely to occur, or from a portion of the first conductor that makes point contact with the dielectric member. In this manner, the first conductor has a discharge origin where electric field concentration is likely to occur, and it is desirable that this origin is disposed opposite the electrode body itself, which has the same potential as the other electrode body, or the second conductor electrically connected to the electrode body via a dielectric member. It is also desirable that the first conductor has multiple such discharge origins. With this configuration, even if one of the origins becomes difficult to function (difficult to discharge), the other origins continue to function, making it less likely that the startability of the ultraviolet light generator will be impaired.

[0009] In the ultraviolet generating device according to the present invention, the dielectric member may be configured as a separate member from the discharge vessel.

[0010] By constructing the dielectric member separately from the discharge vessel, the thickness of the dielectric member can be adjusted as desired. By appropriately adjusting the thickness of the dielectric member, it is possible to suppress the consumption of electrical energy in atmospheric discharge when the excimer lamp is lit.

[0011] In the ultraviolet generating device of the present invention, the thickness of the dielectric member interposed between the first conductor and the other electrode body or the second conductor (shortest distance) may be smaller than the sum of the thickness of the discharge vessel interposed between the first electrode body and the discharge gas and the thickness of the discharge vessel interposed between the second electrode body and the discharge gas.

[0012] With this configuration, the voltage applied to the first electrode body and the second electrode body makes it more likely that insulation breakdown will occur between the first conductor and the other electrode body or the second conductor before the insulation within the discharge vessel is broken down.

[0013] Furthermore, the thickness of the dielectric member interposed between the first conductor and the other electrode body or the second conductor (shortest distance) is preferably 30% or more of the total thickness of the discharge vessel interposed between the first electrode body and the discharge gas and the thickness of the discharge vessel interposed between the second electrode body and the discharge gas, and more preferably 50% or more.

[0014] With this configuration, after the insulation inside the discharge vessel is broken down by the voltage applied to the first electrode body and the second electrode body (after discharge is initiated inside the discharge vessel), the atmospheric discharge between the first conductor and the other electrode body or the second conductor can be further attenuated, and it is expected that the amount of current consumed by the atmospheric discharge after the excimer lamp starts can be reduced. This is expected to suppress a decrease in power to the excimer lamp and a decrease in illuminance. Attenuating the atmospheric discharge after discharge is initiated can also reduce wear on the first conductor, which causes the atmospheric discharge.

[0015] In the ultraviolet generation device according to the present invention, the first conductor may be made of at least one conductive material selected from the group consisting of gold, platinum, tungsten, titanium, aluminum, and stainless steel, or an alloy of the conductive material.

[0016] The material that constitutes the first conductor used to assist in starting the excimer lamp should not exhibit deliquescence. X Gas is produced, but NO XThe gas reacts with moisture in the air to form HNO3 (nitric acid). When the first conductor is immersed in nitric acid, nitrates are formed on the first conductor, and many of these nitrates absorb moisture from the air and dissolve in water, becoming liquid (this is called deliquescence). The formation of deliquescent substances causes liquefaction to form around the first conductor, making it difficult for atmospheric discharge to occur. Note that many discharge lamps have high tube wall temperatures, and when the temperature around the lamp is high, the amount of moisture in the air decreases, making the above problem less likely to occur. However, in the dielectric barrier discharge lamp according to the present invention, the temperature of the discharge vessel is relatively unlikely to increase, making the problem of poor starting performance due to deliquescence more likely to become apparent. Therefore, in the ultraviolet light generator according to the present invention, it is desirable to construct the first conductor from one of the above-listed materials that has high nitric acid resistance to prevent the formation of deliquescent substances.

[0017] In the ultraviolet generating device according to the present invention, the first conductor is preferably made of at least one conductive material selected from the group consisting of gold, platinum, and tungsten, or an alloy of the conductive material.

[0018] Although the above-mentioned titanium, aluminum, and stainless steel are resistant to nitric acid by forming an oxide coating on the metal surface, it is anticipated that atoms without an oxide coating may react with nitric acid due to sputtering in the discharge area caused by atmospheric discharge. Therefore, it is preferable to form the first conductor from a material (gold, platinum, tungsten) whose atoms without a nitric acid coating do not react with nitric acid.

[0019] In the ultraviolet ray generating device according to the present invention, the first conductor extends in a rod shape toward the other electrode body or the second conductor, The first conductor may be configured to generate an atmospheric discharge (here, a corona discharge) starting from the tip of the first conductor.

[0020] In the ultraviolet generating device according to the present invention, the second conductor may have a flat portion facing a tip of the first conductor.

[0021] According to these configurations, a corona discharge is generated starting from the tip of the first conductor, and the light emitted by this corona discharge can improve the starting performance of the excimer lamp.

[0022] In the ultraviolet ray generating device according to the present invention, the first conductor extends in a planar shape facing the other electrode body or the second conductor, The first conductor may be configured to generate a creeping discharge along the surface of the dielectric member, with the first conductor as an origin.

[0023] According to this configuration, a creeping discharge is generated starting from the tip of the first conductor, and the light emitted by this creeping discharge can improve the starting performance of the excimer lamp. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram schematically illustrating one embodiment of the ultraviolet light generating device of the present invention. [Figure 2] FIG. 1 is a perspective view schematically illustrating an example of the appearance of an ultraviolet light generating device. [Figure 3] 3 is a perspective view showing the main body and cover of the casing disassembled from FIG. 2. FIG. [Figure 4] FIG. 4 is a schematic perspective view illustrating a plurality of excimer lamps and electrode bodies extracted from FIG. 3. [Figure 5] FIG. 2 is a schematic diagram for explaining the positional relationship between the excimer lamp and the electrode body, and is a schematic plan view of the excimer lamp as viewed in the +Z direction. [Figure 6] FIG. 2 is a perspective view of the electrode body as seen from the opposite side to the light extraction surface. [Figure 7] FIG. 2 is a plan view of the electrode body as viewed from the opposite side to the light extraction surface. [Figure 8A] FIG. 10 is a plan view schematically showing an electrode body according to another embodiment. [Figure 8B] FIG. 10 is a plan view schematically showing an electrode body according to another embodiment. [Figure 9] FIG. 10 is a plan view schematically showing an electrode body according to another embodiment. [Figure 10] FIG. 10 is a cross-sectional view schematically showing an ultraviolet generator according to a second embodiment. [Figure 11] FIG. 11 is an enlarged view of region XI in FIG. [Figure 12] FIG. 10 is a cross-sectional view schematically showing an ultraviolet light generating device according to another embodiment. [Figure 13] FIG. 10 is a cross-sectional view schematically showing an ultraviolet generator according to a third embodiment. [Figure 14] FIG. 10 is a cross-sectional view schematically showing an ultraviolet generator according to a fourth embodiment. [Figure 15] FIG. 10 is a plan view schematically showing an electrode assembly according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0025] Each embodiment of the ultraviolet light generating 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.

[0026] First Embodiment Fig. 1 is a diagram schematically illustrating one application mode of an ultraviolet light generator according to the present invention. Fig. 1 shows an ultraviolet light generator 1 mounted in a housing 100, and a state in which ultraviolet light L1 is irradiated onto an irradiation target area 40 from a light extraction surface 30 of the ultraviolet light generator 1.

[0027] Fig. 2 is a perspective view schematically showing an example of the appearance of the ultraviolet generator 1. Fig. 3 is a perspective view in which the main body 2a and the lid 2b of the casing 2 of the ultraviolet generator 1 are disassembled from Fig. 2.

[0028] In the following drawings, the explanation will be made with reference to an XYZ coordinate system in which the direction in which ultraviolet light L1 is extracted is the X direction and the plane perpendicular to the X direction is the YZ plane. More specifically, as will be described later with reference to Figure 2 and subsequent drawings, the tube axis direction of the excimer lamp 10 is the Y direction, and the direction perpendicular to the X and Y directions is the Z direction.

[0029] In the following description, when a positive or negative direction is to be distinguished when expressing a direction, the direction is described with a positive or negative sign, such as "+X direction" and "-X direction." When a direction is to be expressed without distinguishing between positive and negative directions, the direction is simply described as "X direction." In other words, in this specification, when simply referring to the "X direction," both the "+X direction" and the "-X direction" are included. The same applies to the Y direction and the Z direction.

[0030] 2 and 3, the ultraviolet generator 1 includes a casing 2 having a light extraction surface 30 formed on one surface. The casing 2 includes a main body 2a and a lid 2b, and the main body 2a accommodates a plurality of excimer lamps 10 and electrode assemblies 21 and 22. In this embodiment, four excimer lamps 10 are accommodated in the casing 2. The electrode assemblies 21 and 22 may be in a form that allows current to be applied to the excimer lamps 10, and may be in the form of, for example, a block, plate, or mesh so as to come into contact with the discharge vessel 11 of the excimer lamp 10.

[0031] Fig. 4 is a perspective view illustrating a plurality of excimer lamps 10 and electrode bodies 21, 22 extracted from Fig. 3. Fig. 5 is a side view schematically illustrating the positional relationship between the excimer lamps 10 and the electrode bodies 21, 22.

[0032] 4, the ultraviolet generator 1 of this embodiment includes four excimer lamps 10 spaced apart in the Z direction. Two electrode bodies 21 and 22 are arranged so as to contact a portion of the outer surface of each excimer lamp 10. Hereinafter, the electrode body 21 may be referred to as the first electrode body 21, and the electrode body 22 may be referred to as the second electrode body 22.

[0033] Each excimer lamp 10 has a discharge vessel 11 with its tube axis oriented in the Y direction, and at positions spaced apart in the Y direction, parts of the outer surface of the discharge vessel 11 of the excimer lamp 10 are in contact with each of the electrode bodies 21, 22. In other words, each of the electrode bodies 21, 22 is in contact with the outer surface of the discharge vessel 11 of the excimer lamp 10 and is arranged so as to straddle each of the excimer lamps 10 in the Z direction.

[0034] As described above, the ultraviolet generator 1 in this embodiment includes a pair of electrode bodies 21 and 22, which are arranged at positions spaced apart from each other in the Y direction. The electrode bodies 21 and 22 are made of a conductive material, and preferably made of a material that is reflective to the ultraviolet rays emitted from the excimer lamp 10. As an example, the electrode bodies 21 and 22 are made of aluminum, an aluminum alloy, stainless steel, or the like.

[0035] When a high-frequency AC voltage, for example, of about 1 kHz to 5 MHz, is applied between the electrode bodies 21, 22, the voltage is applied to the discharge gas 10G sealed inside each excimer lamp 10 via the discharge vessel 11 of each excimer lamp 10. The gas species of the discharge gas 10G may be any material that, when such a voltage is applied, excimer light is emitted when the atoms constituting the gas species are excited or ionized to an excimer state and then transition to the ground state. More specifically, the discharge gas 10G 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).

[0036] As an example, the discharge gas 10G can be a mixture of krypton (Kr), chlorine (Cl), and argon (Ar). In this case, krypton and chlorine function as luminous gases, and argon functions as a buffer gas. The buffer gas can be one or more rare gases selected from argon (Ar), neon (Ne), and helium (He).

[0037] Excimer lamp 10, which uses a mixture of Kr and Cl2 as discharge gas 10G, emits ultraviolet light with a peak wavelength of approximately 222 nm. Even if ultraviolet light in the wavelength range of 190 nm or more and 235 nm or less, including 222 nm, is irradiated onto human skin, it is absorbed by the stratum corneum and does not penetrate further inward (toward the basal layer). Because the keratinocytes contained in the stratum corneum are dead cells, there is virtually no risk of DNA damage caused by absorption by living cells in the spinous layer, granular layer, or dermis, as occurs with irradiation of ultraviolet light with a wavelength of 254 nm.

[0038] It is known that ultraviolet rays in the above wavelength band have a sterilizing effect on objects to be irradiated. Therefore, ultraviolet generators equipped with excimer lamps containing discharge gases as described above are expected to be used in a variety of applications, including photosterilization, and are expected to be used in a wide range of situations.

[0039] Fig. 6 is a perspective view of the block-shaped electrode bodies 21 and 22 as viewed from the opposite side to the light extraction surface 30. Fig. 7 is a plan view of the electrode bodies 21 and 22 as viewed from the opposite side to the light extraction surface 30. In Fig. 7, a dielectric member 6, which will be described later, is shown in cross section.

[0040] The electrode bodies 21, 22 have the same shape. A first recess 23 and a second recess 24 are formed on the -X side surfaces of the electrode bodies 21, 22. The first recess 23 extends in the -Y direction from the +Y side surfaces of the electrode bodies 21, 22. The second recess 24 extends in the +Y direction from the -Y side surfaces of the electrode bodies 21, 22. The first recess 23 and the second recess 24 are arranged to face each other in the Y direction. The first recess 23 and the second recess 24 are formed in the center of the electrode bodies 21, 22 in the Z direction.

[0041] Furthermore, screw holes 25 for connecting a power supply line 7 (see FIG. 2) are formed on the −X side surfaces of the electrode bodies 21 and 22. The high-voltage side power supply line 7 is connected to the screw hole 25 of the first electrode body 21, and the low-voltage side power supply line 7 is connected to the screw hole 25 of the second electrode body 22. However, it is also possible that the low-voltage side power supply line 7 is connected to the screw hole 25 of the first electrode body 21, and the high-voltage side power supply line 7 is connected to the screw hole 25 of the second electrode body 22.

[0042] Additionally, third recesses 26 that come into contact with the outer surface of the discharge vessel 11 of the excimer lamp 10 are formed on the +X side surfaces of the electrode bodies 21, 22. Four third recesses 26 are provided at equal intervals in the Z direction. The first recess 23 and the second recess 24 are disposed between the two central third recesses 26.

[0043] The ultraviolet generator 1 of this embodiment includes a first conductor 5. The first conductor 5 is provided to assist in starting the excimer lamp 10. The first conductor 5 is electrically connected to a first electrode body 21.

[0044] The first conductor 5 of this embodiment is composed of a spring-like proximal portion 5a and a rod-like distal portion 5b, and is elastic as a whole. The proximal portion 5a is electrically connected to the first electrode body 21. The proximal portion 5a is disposed within the first recess 23 of the first electrode body 21, and is in contact with the inner wall 23a on the -Y side of the first recess 23. The proximal portion 5a is pressed against the inner wall 23a of the first recess 23 by its own elastic force.

[0045] In this embodiment, the first conductor 5 is composed of a spring-shaped proximal portion 5a and a rod-shaped distal portion 5b, but the shape of the first conductor 5 is not limited to this. The shape of the first conductor 5 may be columnar, rod-shaped, thin plate-shaped, or the like. The shape of the distal portion 5b of the first conductor 5 is also not limited to a rod shape and may be a thin plate-shaped, but it is preferable that the tip 5c of the distal portion 5b is pointed. This concentrates the electric field at the tip 5c of the first conductor 5, making it easier to discharge at the tip 5c of the first conductor 5.

[0046] The first conductors 5 are made of a conductive material. Preferably, the first conductors 5 are made of at least one conductive material selected from the group consisting of gold, platinum, tungsten, titanium, aluminum, and stainless steel, or an alloy of these conductive materials. More preferably, the first conductors 5 are made of at least one conductive material selected from the group consisting of gold, platinum, and tungsten, or an alloy of these conductive materials.

[0047] A dielectric member 6 is interposed between the first conductor 5 and the second electrode body 22. Specifically, the dielectric member 6 is interposed between the second electrode body 22 and a distal portion 5b extending toward the second electrode body 22 in the Y direction.

[0048] In this specification, the phrase "a dielectric member is interposed between the first conductor and the second electrode body or the second conductor" simply means that the dielectric member is present between the first conductor and the second electrode body or the second conductor, and the dielectric member may or may not be in contact with both. Specifically, in this embodiment, the dielectric member 6 is present between the first conductor 5 and the second electrode body 22, and may or may not be in contact with the first conductor 5 and the second electrode body 22. Furthermore, another member may be present between the dielectric member 6 and the first conductor 5 or the second electrode body 22. Similarly, hereinafter, the phrase "A is interposed between B and C" simply means that A is present between B and C.

[0049] The dielectric member 6 of this embodiment has a cylindrical shape with one end closed. More specifically, the dielectric member 6 has a bottomed cylindrical shape having a cylindrical portion 6a and a bottom portion 6b that closes one end of the cylindrical portion 6a. The cylindrical portion 6a is not limited to a cylindrical shape and may be a rectangular cylindrical shape, etc. The bottom portion 6b is not limited to a flat shape and may be a hemispherical shape, etc.

[0050] The dielectric member 6 is held by the first recess 23 of the first electrode body 21 and the second recess 24 of the second electrode body 22. The cylindrical portion 6a of the dielectric member 6 is slightly smaller than the first recess 23, and the bottom portion 6b is slightly smaller than the second recess 24.

[0051] The dielectric member 6 is disposed so as to cover the tip 5c of the first conductor 5. The tip 5c of the first conductor 5 is pressed against the bottom 6b of the dielectric member 6 by the elastic force of the proximal portion 5a.

[0052] The dielectric member 6 is preferably made of a material that has high insulating properties, high mechanical strength, and high ultraviolet transmittance. For example, the dielectric member 6 is made of quartz glass, ceramics such as alumina, or resin such as PTFE.

[0053] When the ultraviolet generator 1 is operated, a high-frequency voltage is applied between the electrodes 21 and 22 from a power source (not shown) via the power line 7 (see FIG. 2), as described above. This causes the high-frequency voltage to be applied to the discharge gas 10G sealed in each excimer lamp 10 via the discharge vessel 11.

[0054] In excimer lamp 10, a high-frequency voltage is applied between electrode bodies 21 and 22, and the insulation in the discharge space (inside discharge vessel 11) is broken down, causing excimer light emission. When the insulation is broken down, discharge begins and ends repeatedly on the order of nanoseconds, and by performing this at a high frequency, it appears to be lit substantially continuously.

[0055] Incidentally, when halogen gas is enclosed in excimer lamp 10, the high electron affinity of the halogen gas causes it to adsorb electrons, making it difficult for current to flow (electrons to move) unless the lamp is continuously lit. Therefore, in order to improve the starting performance of excimer lamp 10, it is necessary to irradiate the discharge space with light of a wavelength having energy close to the excitation energy of excimer emission, which induces excitation of the excimer in the discharge space (making it easier to discharge).

[0056] In the ultraviolet generator 1 of this embodiment, a voltage is applied between the electrode bodies 21 and 22, and also between the first conductor 5 connected to the first electrode body 21 and the second electrode body 22. At this time, because the distance between the first conductor 5 and the second electrode body 22 is shorter than the distance between the first electrode body 21 and the second electrode body 22, a dielectric breakdown occurs first at a low voltage in the space between the first conductor 5 and the second electrode body 22, and the first conductor 5 generates a corona discharge starting from the tip 5c. As a result, ultraviolet rays are emitted from the tip 5c of the first conductor 5. The wavelength band of the ultraviolet rays at this time includes 226 to 227 nm.

[0057] The light emitted by the atmospheric discharge from the first conductor 5 induces excitation of excimers in the discharge space of the excimer lamp 10 (causing discharge). Therefore, when ultraviolet light is incident from the first conductor 5 while a voltage is applied to the discharge gas 10G through the electrodes 21 and 22, the excimer lamp 10 is lit in a short time (for example, within 0 to 2 seconds) using this light energy as a trigger. When the discharge gas 10G contains krypton (Kr) and chlorine (Cl), the light emitted from the excimer lamp 10 is ultraviolet light with a peak wavelength of 222 nm.

[0058] After the excimer lamp 10 is turned on, the first conductor 5 also continues to light, but because it uses very little power, it does not affect the illuminance of the excimer lamp 10. Furthermore, after the excimer lamp 10 is turned on, the discharge inside the lamp becomes dominant, which acts to suppress atmospheric discharge in the first conductor 5, further reducing the impact.

[0059] Another feature of the first conductor 5 is that after the excimer lamp 10 is lit, the voltage is distributed to the excimer lamp 10 as well, so the voltage applied to the first conductor 5 is lower than at startup, and the load on the first conductor 5 is reduced during continuous lighting, resulting in a longer life as a trigger.

[0060] As described above, the ultraviolet generating device 1 according to the first embodiment comprises an excimer lamp 10 having a discharge vessel 11 in which a discharge gas 10G is sealed, a first electrode body 21 and a second electrode body 22 arranged so as not to be exposed to the discharge gas 10G, and a first conductor 5 electrically connected to the first electrode body 21, the first conductor 5 being arranged opposite the second electrode body 22 via a dielectric member 6, and the first conductor 5 generating an atmospheric discharge (corona discharge) around the tip 5c of the first conductor 5, which is the starting point of the discharge.

[0061] In this specification, "arranging the first electrode body 21 and the second electrode body 22 so that they are not exposed to the discharge gas" not only refers to a form in which the first electrode body 21 and the second electrode body 22 are arranged so as to be in contact with the outer surface of the discharge vessel 11 in which the discharge gas 10G is sealed, but also includes a form in which a portion of the first electrode body 21 and the second electrode body 22 are buried in the outer surface of the discharge vessel 11, a form in which the entire first electrode body 21 and the second electrode body 22 are buried in the discharge vessel 11, etc.

[0062] Furthermore, first conductor 5 is disposed outside discharge vessel 11. For example, in an excimer lamp 90 as shown in Fig. 15 in which electrode blocks 91, 92 are disposed in the longitudinal direction of the excimer lamp 90, the outer surface of the discharge vessel is brought into contact with electrode blocks 91, 92, and a high voltage is applied between electrode blocks 91, 92 to generate a discharge, if the technology described in Patent Document 1 is applied and first conductor 93 is disposed on the inner surface of the discharge vessel, the discharge will concentrate near first conductor 93, reducing the efficiency of ultraviolet radiation emission.

[0063] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configurations should not be considered to be limited to these embodiments. The scope of the present invention is defined not only by the description of the above embodiments but also by the claims, and further includes all modifications within the meaning and scope of the claims.

[0064] The structures employed in the above-described embodiments can be employed in any other embodiment. The specific configurations of the components are not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention.

[0065] <Another embodiment> The combination of the first conductor 5 and the dielectric member 6 is not limited to the above configuration. FIG. 8A is a plan view schematically showing an ultraviolet generator 1 according to another embodiment. In this example, the first conductor 5 is rod-shaped with a pointed tip. The dielectric member 6 is plate-shaped and parallel to the XZ plane. The first conductor 5 and the dielectric member 6 do not necessarily need to be in contact with each other, and may be spaced apart enough to allow discharge. The first conductor 5 does not need to be rod-shaped with a pointed tip. For example, if the first conductor 5 is formed in a rectangular plate shape, there will be two corners that can serve as starting points for discharge. FIG. 8B is a plan view schematically showing an ultraviolet generator 1 according to yet another embodiment. In this example, the first conductor 5 has a coiled portion. The dielectric member 6 is a flat plate parallel to the XZ plane. The first conductor 5 and the dielectric member 6 do not necessarily need to be in contact with each other, and may be spaced apart enough to allow discharge. The atmospheric discharge originates from a point where the coiled portion of the first conductor 5 makes point contact with the dielectric member 6 (or a nearby point). The presence of the coiled portion in the first conductor 5 results in multiple points (originating points) that come into point contact with the dielectric member 6.

[0066] 9 is a plan view schematically showing an ultraviolet generator 1 according to yet another embodiment. In this example, a second conductor 8 is electrically connected to a second electrode body 22. The second electrode body 22 has the same potential as the second conductor 8. That is, a first conductor 5 connected to the first electrode body 21 and extending toward the second electrode body 22, and a second conductor 8 connected to the second electrode body 22 and extending toward the first electrode body 21 are provided. A dielectric member 6 is interposed between the first conductor 5 and the second conductor 8. In this way, the first conductor 5 may be disposed opposite a portion (here, the second conductor 8) having the same potential as the second electrode body 22, with the dielectric member 6 interposed therebetween.

[0067] Second Embodiment The second embodiment has the same configuration as the first embodiment except for the configuration described below, so the commonalities will be omitted and differences will be mainly described. Note that in the second embodiment, elements having substantially the same configuration or substantially the same function (action) as the parts described in the first embodiment will be shown, and their description will not be repeated.

[0068] Fig. 10 is a cross-sectional view schematically showing an ultraviolet generator 1 according to a second embodiment, and Fig. 11 is an enlarged view of region XI in Fig. 10.

[0069] The ultraviolet generator 1 comprises an excimer lamp 10 having a discharge vessel 11 in which a discharge gas 10G is sealed, and a first electrode body 21 and a second electrode body 22 arranged so as not to be exposed to the discharge gas 10G. The first electrode body 21 and the second electrode body 22 are arranged on the outer surface of the discharge vessel 11 at a distance from each other.

[0070] The ultraviolet generator 1 also includes a first conductor 5 electrically connected to the first electrode body 21 and a second conductor 8 electrically connected to the second electrode body 22. The first conductor 5 has the same potential as the first electrode body 21, and the second conductor 8 has the same potential as the second electrode body 22.

[0071] The first conductor 5 has a substantially L-shaped cross section and includes a first connection portion 51 connected to the first electrode body 21 and a first conductor layer 52 extending from the first connection portion 51 in a direction approaching the second electrode body 22. The first connection portion 51 extends in the -X direction from the first electrode body 21. The first conductor layer 52 extends in the +Y direction from the -X direction end of the first connection portion 51. The first conductor layer 52 extends so as to protrude beyond the end face 21a on the +Y side of the first electrode body 21.

[0072] The second conductor 8 includes a second connection portion 81 connected to the second electrode body 22 and a second conductor layer 82 extending from the second connection portion 81 toward the first electrode body 21, and has a substantially L-shaped cross section. The second connection portion 81 extends in the -X direction from the second electrode body 22. The second connection portion 81 has a longer length in the X direction than the first connection portion 51, and the second conductor layer 82 is offset toward the -X side with respect to the first conductor layer 52. The second conductor layer 82 extends in the -Y direction from the -X direction end of the second connection portion 81. The second conductor layer 82 extends so as to protrude beyond the end face 22a on the -Y side of the second electrode body 22. A distance 82d by which the second conductor layer 82 protrudes from the end face 22a is longer than a distance 52d by which the first conductor layer 52 protrudes from the end face 21a.

[0073] The first conductor layer 52 and the second conductor layer 82 partially overlap each other when viewed in the X direction, and the portion of the first conductor layer 52 facing the second conductor layer 82 in the X direction is the conductor portion 53 (or starting point portion). That is, the first conductor 5 has the conductor portion 53 arranged facing the second conductor 8. The conductor portion 53 is arranged so as to be closer to the first electrode body 21 than the second electrode body 22.

[0074] The first conductor 5 and the second conductor 8 are made of a conductive material. Preferably, the first conductor 5 and the second conductor 8 are made of at least one conductive material selected from the group consisting of gold, platinum, tungsten, titanium, aluminum, and stainless steel, or an alloy of these conductive materials. More preferably, the first conductor 5 and the second conductor 8 are made of at least one conductive material selected from the group consisting of gold, platinum, and tungsten, or an alloy of these conductive materials.

[0075] A dielectric member 6 is interposed between the conductor portion 53 and the second conductor layer 82. In this embodiment, the first conductor 5 and the second conductor 8 are substantially entirely embedded in the dielectric member 6 while being spaced apart from each other. Here, the fact that the first conductor 5 and the second conductor 8 are substantially entirely embedded in the dielectric member 6 means that at least a portion of the conductor portion 53 of the first conductor 5 is exposed to the atmosphere. In this embodiment, a portion of the surface on the +X side of the conductor portion 53 (referred to as an exposed portion 53a) is exposed to the atmosphere. The exposed portion 53a is disposed between the first electrode body 21 and the second electrode body 22. Preferably, the exposed portion 53a is disposed so as to face the excimer lamp 10. Note that the exposed portion 53a does not need to be completely exposed to the atmosphere, and may be coated with a thin coating, for example, of approximately 10 to 20 μm, to prevent corrosion.

[0076] The thickness 6t (see FIG. 11) of the dielectric member 6 interposed between the conductor part 53 and the second conductor 8 is smaller than the sum (twice the thickness 11t) of the thickness 11t (see FIG. 10) of the discharge vessel 11 interposed between the first electrode body 21 and the discharge gas 10G and the thickness 11t (see FIG. 10) of the discharge vessel 11 interposed between the second electrode body 22 and the discharge gas 10G (shortest distance). This makes it easier for atmospheric discharge to occur around the conductor part 53.

[0077] The dielectric member 6 is preferably made of a material that has high insulating properties, high mechanical strength, and high ultraviolet transmittance. For example, the dielectric member 6 is made of quartz glass, ceramics such as alumina, or resin such as PTFE.

[0078] In the ultraviolet light generator 1 of this embodiment, a voltage is applied between the electrode bodies 21 and 22, and also between the first conductor 5 connected to the first electrode body 21 and the second conductor 8 connected to the second electrode body 22. At this time, because the distance between the conductor portion 53 of the first conductor 5 and the second conductor 8 is shorter than the distance between the first electrode body 21 and the second electrode body 22, insulation breakdown occurs first at a lower voltage between the conductor portion 53 and the second conductor 8. As a result, a creeping discharge SD occurs along the surface of the dielectric member 6, originating from the exposed portion 53a of the conductor portion 53. This creeping discharge SD emits ultraviolet light L2. The wavelength band of the ultraviolet light L2 at this time includes 226 to 227 nm, and can effectively assist starting discharge even for light emission in a wavelength band shorter than 240 nm.

[0079] The ultraviolet light L2 from the creeping discharge SD induces excitation of excimer in the discharge space of the excimer lamp 10 (causing discharge). Therefore, when ultraviolet light L2 is incident from the first conductor 5 while a voltage is applied to the discharge gas 10G through the electrodes 21 and 22, the excimer lamp 10 is lit in a short time (for example, within 0 to 2 seconds) using this light energy as a trigger. When the discharge gas 10G contains krypton (Kr) and chlorine (Cl), the light emitted from the excimer lamp 10 is ultraviolet light with a peak wavelength of 222 nm.

[0080] As described above, the ultraviolet generating device 1 according to the second embodiment comprises an excimer lamp 10 having a discharge vessel 11 in which a discharge gas 10G is sealed, a first electrode body 21 and a second electrode body 22 arranged so as not to be exposed to the discharge gas 10G, and a first conductor 5 electrically connected to the first electrode body 21, the first conductor 5 being arranged opposite the second conductor 8 via a dielectric member 6, and the first conductor 5 generating an atmospheric discharge (creeping discharge) around the tip (conductor portion 53) of the first conductor 5, which is the starting point of the discharge.

[0081] <Another embodiment> 12 is a cross-sectional view schematically showing an ultraviolet generator 1 according to another embodiment. In this example, the first conductor 5 has a conductor portion 54 arranged opposite to the second electrode body 22 with a dielectric member 6 interposed therebetween. In other words, this ultraviolet generator 1 does not include a second conductor 8.

[0082] The conductor portion 54 extends in the +X direction from the end portion of the first conductor layer 52 in the +Y direction. The conductor portion 54 also extends in a planar shape facing the end face 22a on the -Y side of the second electrode body 22. A portion of the surface of the conductor portion 54 on the -Y side (referred to as the exposed portion 54a) is exposed to the atmosphere. As a result, similar to the second embodiment described above, a creeping discharge SD occurs along the surface of the dielectric member 6, starting from the exposed portion 54a of the conductor portion 54, and ultraviolet light L2 is emitted by this creeping discharge SD.

[0083] <Third embodiment> The third embodiment has the same configuration as the first embodiment except for the configuration described below, so the commonalities will be omitted and differences will be mainly described. Note that in the third embodiment, elements having substantially the same configuration or substantially the same function (action) as the parts described in the first embodiment will be shown, and their description will not be repeated.

[0084] FIG. 13 is a cross-sectional view schematically showing an ultraviolet generator 1 according to the third embodiment.

[0085] The ultraviolet generating device 1 comprises an excimer lamp 10 having a discharge vessel 11 in which a discharge gas 10G is sealed, and a first electrode body 21 and a second electrode body 22 arranged so as not to be exposed to the discharge gas 10G.

[0086] Discharge vessel 11 has a shape that is elongated in a direction perpendicular to the plane of the paper on which Fig. 13 is drawn. Discharge vessel 11 has a generally rectangular shape with a flat cross section, and has a pair of flat walls 11a, 11b.

[0087] A first electrode body 21 and a second electrode body 22 are provided on the outer surfaces of a pair of flat walls 11a, 11b of the discharge vessel 11, respectively. The first electrode body 21 is connected to, for example, the high-voltage side of a power supply, and the second electrode body 22 is connected to, for example, the low-voltage side of the power supply. At least one of the first electrode body 21 and the second electrode body 22 is configured with a shape and material that transmits ultraviolet light or has a small light-blocking area. In this embodiment, the second electrode body 22 is configured with a metal having, for example, a mesh shape or coil shape. On the other hand, the first electrode body 21 is formed in a solid shape. Note that the first electrode body 21 and the second electrode body 22 may have any shape as long as they are light-transmitting, and may be, for example, electrodes with slits.

[0088] The ultraviolet generator 1 includes a first conductor 5 electrically connected to a first electrode body 21, and a second conductor 8 electrically connected to a second electrode body 22. The first conductor 5 has a conductor portion 55 arranged opposite to the second conductor 8 with a dielectric member 6 interposed therebetween. The conductor portion 55 extends in a rod shape toward the second conductor 8.

[0089] The second conductor 8 has a flat portion 8a facing the tip 55a of the conductor portion 55. The dielectric member 6 is flat and has an area covering the entire flat portion 8a. The dielectric member 6 is sandwiched between the tip 55a of the first conductor 5 and the flat portion 8a of the second conductor 8.

[0090] When a voltage is applied between the first electrode body 21 and the second electrode body 22, a voltage is also applied between the first conductor 5 connected to the first electrode body 21 and the second conductor 8 connected to the second electrode body 22. At this time, because the distance between the tip 55a of the conductor portion 55 and the flat portion 8a of the second conductor 8 is shorter than the distance between the first electrode body 21 and the second electrode body 22, insulation breakdown occurs first at a low voltage in the space between the tip 55a and the flat portion 8a, causing the first conductor 5 to generate a corona discharge starting from the tip 55a. This causes ultraviolet light L2 to be emitted from the tip 55a of the first conductor 5.

[0091] <Fourth embodiment> The fourth embodiment has the same configuration as the third embodiment except for the configuration described below, so the commonalities will be omitted and differences will be mainly described. Note that the fourth embodiment represents elements having substantially the same configuration or substantially the same function (action) as the parts described in the third embodiment, and their description will not be repeated.

[0092] FIG. 14 is a cross-sectional view schematically showing an ultraviolet generator 1 according to the fourth embodiment.

[0093] The ultraviolet generating device 1 comprises an excimer lamp 10 having a discharge vessel 11 in which a discharge gas 10G is sealed, and a first electrode body 21 and a second electrode body 22 arranged so as not to be exposed to the discharge gas 10G.

[0094] Discharge vessel 11 has a double-tube structure with a tube axis extending parallel to the plane of the paper in Fig. 14. Discharge vessel 11 comprises an inner tube 11c and an outer tube 11d that surrounds inner tube 11c. Discharge gas 10G is filled in the space between inner tube 11c and outer tube 11d.

[0095] A first electrode body 21 is provided on the inner peripheral wall of the inner tube 11c. A second electrode body 22 is provided on the outer peripheral wall of the outer tube 11d. The first electrode body 21 is connected to, for example, the high-voltage side of a power supply, and the second electrode body 22 is connected to, for example, the low-voltage side of the power supply. Of the first electrode body 21 and the second electrode body 22, at least the second electrode body 22 is configured with a shape and material that transmits ultraviolet light or has a small light-blocking area. In this embodiment, the second electrode body 22 is configured with a metal having, for example, a mesh-like or coil-like shape.

[0096] Furthermore, it is desirable that the starting point of the first conductor 5 according to the present invention is positioned so that it faces the discharge vessel 11 of the excimer lamp 10. This allows the ultraviolet light generated at the starting point of the first conductor 5 to easily reach the discharge space in the excimer lamp 10 without being blocked, making it easier to induce excitation of excimers in the discharge space (facilitating discharge). In this case, a member that transmits ultraviolet light may be interposed between the discharge vessel 11 of the excimer lamp and the starting point. Furthermore, from the viewpoint of guiding ultraviolet light with a short wavelength band to the discharge vessel 11 without attenuation, it is more desirable that there is no intervening object between the discharge vessel 11 and the starting point.

[0097] Furthermore, it is desirable that the starting point of the first conductor 5 according to the present invention is located in a position close to the discharge vessel 11 of the excimer lamp 10. This makes it easier for even the slight short-wavelength ultraviolet light generated at the starting point of the first conductor 5 to reach the discharge space within the excimer lamp 10, making it easier to induce excitation of excimers in the discharge space (making it easier to discharge). Specifically, the distance between the discharge vessel 11 of the excimer lamp 10 and the starting point is configured to be less than 30 mm, and more desirably the distance is 20 mm or less, and more desirably 15 mm or less. [Explanation of symbols]

[0098] 1: UV generator 5: First conductor 5a: Proximal part 5b: distal part 5c: tip 6: Dielectric material 8: Second conductor 8a: Flat part 10: Excimer lamp 10G: Discharge gas 11: Discharge vessel 21:First electrode body 22:Second electrode body 53: Conductor 53a:Exposed part 54: Conductor 54a:Exposed part 55: Conductor 55a: apex L1: Ultraviolet rays L2: Ultraviolet rays SD: Surface discharge

Claims

1. an excimer lamp having a discharge vessel in which a discharge gas is sealed; a first electrode body and a second electrode body arranged so as not to be exposed to the discharge gas; a first conductor electrically connected to either the first electrode body or the second electrode body, the first conductor has a portion disposed opposite to the other electrode body or a second conductor electrically connected to the other electrode body via a dielectric member; The first conductor generates an atmospheric discharge around the first conductor.

2. 2. The ultraviolet generating device according to claim 1, wherein the dielectric member is configured as a separate member from the discharge vessel.

3. 2. The ultraviolet generating device of claim 1, wherein the thickness of the dielectric member interposed between the first conductor and the other electrode body or the second conductor is smaller than the sum of the thickness of the discharge vessel interposed between the first electrode body and the discharge gas and the thickness of the discharge vessel interposed between the second electrode body and the discharge gas.

4. The ultraviolet generating device according to any one of claims 1 to 3, wherein the first conductor is made of at least one conductive material selected from the group consisting of gold, platinum, tungsten, titanium, aluminum, and stainless steel, or an alloy of the conductive material.

5. 5. The ultraviolet generating device according to claim 4, wherein the first conductor is made of at least one conductive material selected from the group consisting of gold, platinum, and tungsten, or an alloy of the conductive material.

6. the first conductor extends in a rod shape toward the other electrode body or the second conductor, The ultraviolet generating device according to claim 1 , wherein the first conductor generates atmospheric discharge starting from a tip of the first conductor.

7. The ultraviolet generating device according to claim 6 , wherein the second conductor has a flat portion facing a tip of the first conductor.

8. the first conductor extends in a planar shape facing the other electrode body or the second conductor, The ultraviolet generating device according to claim 1 , wherein the first conductor generates a creeping discharge along the surface of the dielectric member, the creeping discharge originating from a tip of the first conductor.

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