Excimer lamp

Abstract

To provide an excimer lamp capable of suppressing the occurrence of abnormal discharge and achieving high illuminance.SOLUTION: An excimer lamp 10 includes a discharge tube 20 having a double-tube structure in which an inner tube 50 is welded to an outer tube 25, and an inner electrode 30 covered with a dielectric 50 is provided within the discharge tube 20 along the lamp axis C. An outer electrode 40 is provided on an outer surface 20S of the discharge tube 20 (outer tube 25). The outer electrode 40 is provided along the lamp axis C up to a position covering the welded portion M, and an outer tube extension 27 is provided outward in the lamp axial direction beyond the welded portion M.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an excimer lamp, and more particularly to the configuration of a discharge tube. [Background technology]

[0002] In a double-tube excimer lamp, a discharge gas is sealed inside a discharge tube made by welding an inner tube to an outer tube. An inner electrode is placed inside the inner tube, an outer electrode is provided on the outer surface of the discharge tube, and a power feed rod (power feed line) is connected to the inner electrode. Excimer light (ultraviolet rays) is emitted by applying a high-frequency voltage between the inner and outer electrodes.

[0003] The material and configuration of the outer electrode provided on the outer surface of the discharge tube are determined according to the irradiation method, etc. For example, in a spot irradiation type compact excimer lamp, a light emitting surface is provided at the end of the light emitting tube, and an aluminum film is provided as an outer electrode on the outer surface of the discharge tube (see Patent Document 1). Also, in an excimer lamp placed inside a jacket tube, the aluminum film that constitutes the outer electrode is formed in a strip shape on the surface of the discharge tube (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6557011 [Patent Document 2] JP 2022-137996 A Summary of the Invention [Problem to be solved by the invention]

[0005] To increase the illuminance of a lamp, an outer electrode such as an aluminum film is provided not only on the cylindrical surface along the axis of the discharge tube, but also on the welded part between the outer tube and the inner tube and on the end surface of the discharge tube. In such an arrangement of the outer electrode, when a high voltage is applied, abnormal discharge, including creeping discharge, is likely to occur between the outer electrode and the power supply rod through the welded part. Abnormal discharge can lead to lamp damage and reduced illuminance.

[0006] Therefore, there is a demand for providing an excimer lamp that is capable of suppressing the occurrence of abnormal discharge and achieving high illuminance. [Means for solving the problem]

[0007] An excimer lamp according to one aspect of the present invention comprises a discharge tube in which a discharge space is formed by welding an outer tube and an inner tube together, and an outer electrode provided on the outer surface of the outer tube, the outer electrode being arranged to extend beyond the discharge space in the lamp axial direction outward, and an outer tube extension portion is provided on the outer tube, extending beyond the welded portion between the outer tube and the inner tube in the lamp axial direction outward.

[0008] The outer electrode may have various configurations, for example, a film, plate or block shape, and reflects the light emitted from the discharge space.

[0009] The arrangement of the outer electrode may vary for discharge tubes with outer tube extensions. For example, the outer electrode may be configured to cover at least a portion of the weld. The outer electrode may cover at least a portion of the outer tube extension. Alternatively, for discharge tubes with a foil-like inner electrode that is coated on the inner tube, the outer electrode may be arranged beyond the end of the inner electrode along the tube axis.

[0010] The outer tube extension may be configured (molded) in various ways. For example, the outer tube extension may be configured as a portion that extends outward in the lamp axial direction from the welded portion. Also, the outer tube extension may be configured as a separate member that is welded coaxially to the outer tube.

[0011] For a discharge tube provided with a foil-shaped inner electrode covering the inner tube, it is possible to provide an inner tube extension that extends outward in the lamp axial direction beyond the welded portion on the inner tube. The inner tube extension can be configured so that the inner diameter of the inner tube extension is smaller than the width of the inner electrode and / or the thickness of the inner tube extension is larger than the thickness of the inner tube. Effect of the Invention

[0012] According to the present invention, it is possible to provide an excimer lamp capable of suppressing the occurrence of abnormal discharge and achieving high illuminance. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view taken along the electrode width direction of an excimer lamp according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] 6 is a schematic cross-sectional view taken along the electrode width direction of an excimer lamp according to a second embodiment. FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] 11 is a schematic cross-sectional view taken along the electrode width direction of an excimer lamp according to a third embodiment. FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The excimer lamp 10 is a spot irradiation type excimer lamp, and is configured here as a small spot irradiation type excimer lamp. The excimer lamp 10 includes a cylindrical discharge tube (discharge vessel) 20 with a bottom made of a dielectric material such as quartz glass, and one end, which is the bottom portion of the cylindrical discharge tube 20 with a bottom, is configured as an emission surface (emission surface) 20D of light including ultraviolet rays.

[0015] Here, the discharge tube 20 is configured as a discharge tube with a circular cross section along the tube diameter (lamp diameter) direction, and is configured so that the inner diameter and thickness are constant along the tube axis (lamp axis) C. A rare gas such as xenon gas or a mixed gas of a rare gas and a halogen gas is sealed in the discharge space S inside the discharge tube 20 as a discharge gas. An emission surface 20D of the discharge tube 20 is made of a material that transmits light radiated from a discharge generated in the discharge space S.

[0016] A foil electrode 30 extending in a strip shape along the tube axis C is disposed within the discharge tube 20. The foil electrode (hereinafter also referred to as the inner electrode) 30 is covered (sealed) by a columnar dielectric 50 made of quartz glass or the like, and is embedded within the dielectric 50 without being exposed to the discharge space S. One end 30T of the foil electrode 30 along the lamp axis C is connected to a power supply line (power supply rod) 60, which is connected to an externally installed power supply unit (not shown).

[0017] The dielectric 50 has a flange portion (hereinafter referred to as the welded portion) M that protrudes radially like a flange, and the discharge tube 20 employs a double-tube structure in which the dielectric 50 is welded to a tubular portion 25 that forms the discharge space S. In the following, as necessary, the portion of the dielectric 50 that is exposed in the discharge space S will be referred to as the "inner tube" and the tubular portion 25 that forms the discharge space S will be referred to as the "outer tube."

[0018] The foil electrode 30 is arranged coaxially with respect to the discharge tube 20, and the dielectric 50 is also arranged coaxially with respect to the discharge tube 20. Therefore, the foil electrode 30 is arranged coaxially with its center position in the width direction and thickness direction aligned with the center position of the dielectric 50. Also, they are arranged symmetrically with respect to the tube axis C. In Figs. 1 and 2, the width direction of the foil electrode 30 is defined as the Y direction, and the direction perpendicular thereto (thickness direction) is defined as the X direction.

[0019] As shown in Figure 2, the foil electrode 30 has a generally constant cross-sectional shape along the lamp axis C, and has a wedge shape that is sharpened from a flat portion of constant thickness toward both ends in the width direction. This makes it possible to concentrate the electric field strength at the edge of the foil electrode 30 while suppressing the occurrence of peeling between the inner tube 50 and the foil electrode 30.

[0020] On the other hand, the inner tube 50, which is a dielectric, has a flat external shape along the width direction of the foil electrode 30, is elongated along the width direction of the foil electrode 30, and has a flat surface portion with a substantially constant thickness along the thickness direction of the foil electrode 30, so that its cross-sectional area is smaller than that of a dielectric with a circular cross section, and the volume of the discharge space S is secured.

[0021] An outer electrode 40 is provided on the outer surface of the outer tube 25 constituting the discharge tube 20, i.e., the outer surface 20S of the discharge tube 20. The outer electrode 40 is made of a material that reflects light such as ultraviolet rays emitted from the discharge space S, and is made of, for example, a film or plate that has thermal conductivity and electrical conductivity. The outer electrode 40 can be made of, for example, a film (such as an aluminum film) that reflects light including ultraviolet rays with a wavelength of 172 nm.

[0022] The outer electrode 40 is formed in an annular shape so as to cover the outer surface 20S of the discharge tube 20 over the entire circumferential direction along the lamp axis (tube axis) C. The outer electrode 40 also extends along the lamp axis C so that one end 40T thereof reaches the welded portion M. The end 40T of the outer electrode 40 is located outside in the lamp axial direction of the lamp further than the section L in which the discharge space S is formed along the lamp axis C, and reaches a position covering a part of the welded portion M.

[0023] In addition to the arrangement in which the outer electrode 40 is disposed up to the welded portion M, the outer tube 25 is provided with an extension portion (hereinafter, referred to as outer tube extension portion) 27 that extends outward in the lamp axial direction from the welded portion M. The outer tube extension portion 27 is formed integrally with the outer tube 25 here, and is configured as a part of the outer tube 25.

[0024] A cylindrical extension (hereinafter referred to as an inner extension) 55 is formed on the inner tube 50 in the discharge tube 20. The extension (hereinafter referred to as an inner extension) 55 extends coaxially from the welded part M with the outer tube 25 toward the outside in the lamp axial direction and has an opening protruding outside the discharge tube 20. The power supply rod 60 is covered by the inner extension 55 and partially sealed. The position along the lamp axis C of the connection part 54 connecting the inner tube 50 and the welded part M corresponds to the end 30T of the foil electrode 30.

[0025] The inner tube extension 55 is configured to be thicker than the inner tube 50. The outer diameter D1 of the inner extension 55 is larger than the electrode width direction length W1 and the electrode thickness direction length W2 of the inner tube 50, and the inner diameter D2 is smaller than the width W0 of the foil electrode 30.

[0026] When a high-frequency voltage (e.g., a voltage in the range of several kV to several tens of kV at a frequency of several kHz to several tens of MHz) is applied between the foil electrode 30 and the outer electrode 40, a dielectric barrier discharge is generated between the outer surface of the dielectric 50 covering the foil electrode 30 and the inner surface of the discharge tube 20 covered by the outer electrode 40, and excimer light of a predetermined spectrum (e.g., a wavelength of 172 nm) is radiated from the discharge space S.

[0027] The light emitted from the discharge space S is reflected by the outer electrode 40, and is guided to the emission surface 20D side by the fiber effect of the dielectric 50 and the discharge tube 20, and is emitted from the emission surface 20D. By arranging an irradiation target opposite the emission surface 20D, light irradiation, ultraviolet irradiation, and the like are performed.

[0028] As described above, the outer electrode 40 extends along the lamp axis C until its end 40T is located at the welded portion M. Meanwhile, the outer tube extension 27 extending coaxially from the outer tube 25 is formed outward in the lamp axial direction from the welded portion M. Although the end 40T of the outer electrode 40 is located very close to the outer surface of the welded portion M, it does not come into contact with the surface of the welded portion M due to the configuration in which the outer tube extension 27 is interposed therebetween.

[0029] Therefore, even when a high voltage is applied to increase the ultraviolet illuminance, it is possible to prevent creeping discharge from the end 40T of the outer electrode 40 along the surface of the inner tube extension 55 that is sealed to the power feed rod 60. In addition, it is possible to suppress the occurrence of dielectric breakdown and abnormal discharge between the outer electrode 40 and the power feed rod 60 via the inner tube extension 55.

[0030] Furthermore, since the inner tube extension 55 is configured to be thicker than the inner tube 50, the thickness and outer diameter of the inner tube 50 exposed in the discharge space S can be made relatively small to seal the foil electrode 30, thereby improving the ultraviolet radiation efficiency, while sealing the power supply rod 60 with the inner extension 55, which has a relatively large thickness and outer diameter, can effectively suppress abnormal discharge due to surface discharge and insulation breakdown.

[0031] The position of the end 40T of the outer electrode 40 can be determined as appropriate. For example, it may be disposed so as to cover the entire welded portion M. Alternatively, the outer electrode 40 may be disposed so as to cover at least a portion of the outer surface of the outer tube extension 27, or may be disposed so as to cover the entire outer surface of the outer tube extension 27. This allows the reflective surface of light including ultraviolet light to be expanded, thereby further increasing the illuminance.

[0032] In a configuration using the foil electrode 30 as in this embodiment, the outer electrode 40 may be provided so as to extend beyond the end 30T of the foil electrode 30, which is the end of the electrode opposing section between the foil electrode 30 and the outer electrode 40. Also, the inner tube extension 55 may not be provided, and the power supply rod 60 may be exposed.

[0033] The above-described excimer lamp 10 can be manufactured, for example, by the following manufacturing method.

[0034] First, a power supply rod 60 is connected to the foil electrode 30 by resistance welding or the like, and then inserted into a glass tube that will become the inner tube 50. After inserting the foil electrode, the glass tube is evacuated, and then the glass tube is heated from the outside to seal it with the foil electrode 30. At this time, heating is adjusted so that the cross-sectional shape of the inner tube 50 described above is obtained.

[0035] For example, by rotating the glass tube and heating it with a burner or the like, the glass tube is uniformly circumferentially contracted (reduced in diameter) until the inner surface of the glass tube comes into contact with both ends (wedge-shaped portions) of the foil electrode, and the glass tube between the parts that come into contact with both ends (wedge-shaped portions) of the foil electrode is contracted along the thickness direction of the foil electrode to be integrated with the flat portion, thereby making it possible to form an inner tube with an oblong or elliptical cross section. Note that a process of coating a dielectric or a process of cutting the glass tube may be performed instead.

[0036] A brim-shaped welding part is formed at a position of the glass tube corresponding to the electrode edge along the tube axis direction. Then, a discharge tube such as quartz glass is formed with an emission surface (exit surface) 20D of light including ultraviolet rays at one end, which is the bottom part of the bottomed cylinder, an exhaust tube is provided on a part of the outer surface on the other end side, and an insertion port is provided at the other end. An inner tube with a foil electrode sealed thereto is inserted into the discharge tube, and the insertion port of the discharge tube is welded to the welding part.

[0037] While heating the entire discharge tube, a vacuum is drawn through the exhaust tube to remove impurities. After filling the discharge gas, the exhaust tube is sealed and an outer electrode is provided on the outer surface of the discharge tube. At this time, the outer electrode is formed directly on the outer surface of the discharge tube by sputtering after masking the areas on the outer surface of the discharge tube where the outer electrode is not to be provided, such as the emission surface, and surface treatment is performed by irradiating the areas where the outer electrode is to be provided with ultraviolet light.

[0038] The outer tube extension may be prepared as a separate member and fused to the outer tube instead of being configured as a part of the outer tube as described above. For example, it is possible to use synthetic quartz glass with high UV transmittance for the outer tube, while using relatively inexpensive fused quartz for the outer tube extension. Also, thin (small thickness) quartz glass may be used for the outer tube to increase UV transmittance, while a thick glass tube may be used to configure the outer tube extension.

[0039] When the outer pipe extension portion is constructed as a separate member in this manner, the outer pipe extension portion may be welded integrally with the outer pipe and then welded to the welded portion (flange portion) of the inner pipe, or the outer pipe extension portion may be welded to the welded portion (flange portion) between the outer pipe and the inner pipe.

[0040] As described above, the excimer lamp 10 of this embodiment includes the discharge tube 20 having a double tube structure in which the inner tube 50 is welded to the outer tube 25, and the outer electrode 40 is disposed on the outer surface 20S of the discharge tube 20 (outer tube 25). The outer electrode 40 is disposed along the lamp axis C up to a position covering the welded portion M, and the outer tube extension 27 is provided toward the outside of the lamp axis beyond the welded portion M.

[0041] Next, an excimer lamp according to a second embodiment will be described with reference to Figures 3 and 4. In the second embodiment, the excimer lamp is configured as a line irradiation type excimer lamp.

[0042] Fig. 3 is a schematic cross-sectional view taken along the electrode width direction of an excimer lamp according to a second embodiment of the present invention, and Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3.

[0043] The excimer lamp 100 is configured as a line irradiation type excimer lamp, and can irradiate light including ultraviolet rays linearly from a slit-shaped emission surface (exit surface) along the lamp axis C. The outer surface portion of the discharge tube 20 that is not covered by the outer electrode 140 is configured as a window W for emitting light. The area occupied by the window W is defined here as half the area in the circumferential direction of the discharge tube 20 (see FIG. 4).

[0044] As in the first embodiment, the discharge tube 120 has a double tube structure in which the inner tube 50 is welded to the outer tube 125, and the outer electrode 140 extends along the lamp axis C so as to reach the welded part M along the lamp axis C. Meanwhile, the outer tube 125 has an outer tube extension part 127 formed coaxially toward the outside in the lamp axial direction beyond the welded part M. Therefore, even in the line irradiation type excimer lamp 100, it is possible to suppress abnormal discharge due to surface discharge and insulation breakdown while achieving high illuminance.

[0045] Next, an excimer lamp according to a third embodiment will be described with reference to Figures 5 and 6. In the third embodiment, the excimer lamp is configured as a line irradiation type excimer lamp using a reflection block.

[0046] Fig. 5 is a schematic cross-sectional view taken along the electrode width direction of an excimer lamp according to a third embodiment of the present invention, and Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 5.

[0047] The excimer lamp 200 includes a block-shaped outer electrode 240. A recess 240T is formed in the outer electrode 240 to match the shape of the outer surface of the outer tube 225. The discharge tube 220 is placed in the recess 240T formed in the outer electrode 240, and is held by a holding member (not shown). The outer electrode 240 is made of a material that reflects ultraviolet rays, such as aluminum, and reflects light, including ultraviolet rays, emitted from the discharge space S by the recess 240T.

[0048] Here, the block-shaped outer electrode 240 extends along the lamp axis C beyond the welded portion M and further beyond the outer extension portion 227. In this excimer lamp 200, too, it is possible to achieve high illuminance while suppressing the occurrence of abnormal discharge due to surface discharge and dielectric breakdown.

[0049] In addition, the excimer lamp shown in the above-mentioned Patent Document 2, that is, an excimer lamp in which band-shaped outer electrodes are arranged at intervals in the circumferential direction along the lamp axis of the discharge tube and both ends of the discharge tube are covered with an aluminum film, can also be configured to have an outer tube extension portion, as in the first to third embodiments. [Explanation of symbols]

[0050] 10 Excimer Lamp 20 discharge tube 25 Outer tube 27 Outer tube extension 40 outer electrode 50 Dielectric (inner tube) 60 Power supply rod M Melting area

Claims

1. a discharge tube in which a discharge space is formed by welding an outer tube and an inner tube; an outer electrode provided on an outer surface of the outer tube; the outer electrode is disposed outside the discharge space in the lamp axial direction, 1. An excimer lamp comprising: an outer tube extension portion provided on the outer tube, the outer tube extending outward in the lamp axial direction beyond a welded portion between the outer tube and the inner tube.

2. 2. The excimer lamp of claim 1, wherein the outer electrode covers at least a portion of the welded portion.

3. 2. The excimer lamp of claim 1 wherein said outer electrode covers at least a portion of said outer tube extension.

4. a foil-shaped inner electrode covering the inner tube; 2. The excimer lamp according to claim 1, wherein the outer electrode is disposed beyond an end of the inner electrode along the tube axis.

5. 2. The excimer lamp according to claim 1, wherein the outer tube extension portion is configured as a portion that extends outward in the lamp axial direction beyond the welded portion.

6. 2. The excimer lamp of claim 1, wherein the outer tube extension is constructed as a separate member that is coaxially welded to the outer tube.

7. a foil-shaped inner electrode covering the inner tube; an inner tube extension portion is provided on the inner tube, the inner tube extending outward in the lamp axial direction beyond the welded portion; The inner diameter of the inner tube extension portion is smaller than the width of the inner electrode, 2. The excimer lamp of claim 1, wherein the thickness of the inner tube extension is greater than the thickness of the inner tube.

8. 2. The excimer lamp according to claim 1, wherein the outer electrode is formed in a film, plate or block shape and reflects light emitted from the discharge space.

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