Excimer lamp

Abstract

The invention provides an excimer lamp. The purpose of the present invention is to efficiently irradiate light such as ultraviolet light toward an object to be irradiated in a spot irradiation type excimer lamp. An excimer lamp (10) is provided with: a discharge tube (20); a foil electrode (30) extending along a tube axis (C) within the discharge tube (20); an outer electrode (40) that covers the outer surface of the discharge tube (20); and a dielectric (50) that covers the foil electrode (30). The dielectric (50) has a flat shape in the width direction (Y direction) of the foil electrode (30).

Description

Technical Field

[0001] The present invention relates to an excimer lamp, and more particularly to an excimer lamp that irradiates light in the direction of a lamp axis (hereinafter referred to as a spot irradiation type excimer lamp). Background Art

[0002] In a point-irradiation excimer lamp, one end of the discharge tube is set as the light emission surface (exit surface), and a film-shaped outer electrode (aluminum film, etc.) that reflects, for example, ultraviolet rays is set to cover the outer surface of the discharge tube (for example, refer to Patent Document 1).

[0003] The excimer light emitted by the discharge generated by applying a high-frequency voltage between the inner electrode and the outer electrode arranged in the discharge tube is guided to the emission surface side of the discharge tube by reflection from the outer electrode, and the ultraviolet light is guided to the emission surface side by the optical fiber effect that allows the ultraviolet light to pass through the tube wall of the discharge tube, thereby radiating ultraviolet light from the lamp emission surface.

[0004] Patent Document 1: Japanese Patent No. 6557011

[0005] For example, when constructing a small point irradiation type excimer lamp (for example, the outer diameter of the discharge vessel is several to several tens of mm), it is sometimes necessary to place the irradiation object close to it and irradiate it with ultraviolet light or the like in a concentrated manner. In such a case, efficient irradiation of light is also required. Summary of the invention

[0006] An excimer lamp as one embodiment of the present invention comprises a discharge tube having a light emitting surface formed at one end thereof and a dielectric covering a foil electrode extending in a strip shape in the discharge tube. The foil electrode may be arranged to extend in the tube axis (lamp axis) direction of the tubular discharge container, for example.

[0007] The structure of the foil electrode is various, and the foil electrode can be configured so that the two ends of the foil electrode along the width direction are thinner than the center of the foil electrode along the width direction. For example, the foil electrode can be formed into a shape as follows: there is a flat portion with a substantially constant thickness along the width direction between the two ends of the foil electrode along the width direction, and the foil electrode is sharpened from the two ends of the flat portion toward the two ends of the foil electrode along the width direction.

[0008] In the excimer lamp of the present invention, the dielectric is flat in the width direction of the foil electrode. Here, "flat in the width direction of the foil electrode" means a shape having a flat surface portion that is elongated in the width direction of the foil electrode and has a substantially constant thickness in the thickness direction of the foil electrode. Such a flat shape can be said to be a shape obtained by flattening in the thickness direction of the foil electrode.

[0009] The dielectric and the foil electrode may be arranged in various configurations, and the foil electrode and the dielectric may be arranged coaxially, and the distance between the outer surface of the dielectric and the foil electrode along the thickness direction of the foil electrode may be shorter than the distance between the outer surface of the dielectric and the foil electrode along the width direction of the foil electrode.

[0010] The dielectric may be configured such that its flat shape is set based on the position of the foil electrode, that is, the width direction. For example, the dielectric may be configured such that an outer surface is substantially parallel to the width direction of the foil electrode. Furthermore, the dielectric may be configured such that an outer surface is substantially perpendicular to the discharge surface.

[0011] The dielectric can be applied in various shapes as the specific shape of the flat shape. For example, the cross section of the dielectric can be configured to be an oblong (oval) or oblong. In addition, the dielectric can be configured to have a small diameter portion formed inside the discharge tube and a large diameter portion formed outside the discharge tube, and the diameter of the small diameter portion along the width direction and the thickness direction of the foil electrode is smaller than the diameter of the large diameter portion.

[0012] According to the present invention, in the spot irradiation type excimer lamp, light can be efficiently irradiated toward an irradiation object. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic cross-sectional view of the excimer lamp according to the present embodiment, taken along the electrode width direction.

[0014] Figure 2 This is a schematic side view of the excimer lamp according to the present embodiment as viewed from the emission surface side.

[0015] Figure 3 It is a cross-sectional view of the excimer lamp according to the present embodiment, taken along the electrode thickness direction.

[0016] Figure 4 is an enlarged cross-sectional view of the foil electrode.

[0017] Figure 5 is an enlarged cross-sectional view of a foil electrode and a dielectric covering the foil electrode.

[0018] Description of symbols

[0019] 10: Excimer lamp; 20: discharge tube; 20D: discharge surface; 30: inner electrode (foil electrode); 40: outer electrode; 50: dielectric. DETAILED DESCRIPTION

[0020] Hereinafter, the excimer lamp according to the present embodiment will be described with reference to the drawings.

[0021] Figure 1 This is a schematic cross-sectional view of the excimer lamp according to the present embodiment, taken along the electrode width direction. Figure 2This is a schematic side view of the excimer lamp according to the present embodiment as viewed from the emission surface side. Figure 3 It is a cross-sectional view of the excimer lamp according to the present embodiment, taken along the electrode thickness direction.

[0022] The excimer lamp 10 is a point irradiation type excimer lamp, and here, it is configured as a small point irradiation type excimer lamp. The excimer lamp 10 has a bottomed cylindrical discharge tube (discharge container) 20 made of a dielectric material such as quartz glass, and one end of the bottomed cylindrical discharge tube 20 as the bottom portion is configured as a light emission surface (emission surface) 20D including ultraviolet rays.

[0023] Here, the discharge tube 20 is configured as a discharge tube having 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 or a mixed gas thereof is sealed as a discharge gas in the discharge space S in the discharge tube 20. The discharge surface 20D of the discharge tube 20 is formed of a material that allows light emitted by the discharge generated in the discharge space S to pass through.

[0024] A foil electrode 30 extending in a strip shape along the tube axis C is arranged in the discharge tube 20. The foil electrode 30 is covered (sealed) by a columnar dielectric 50 made of quartz glass or the like, and is not exposed to the discharge space S, but is buried in the dielectric 50. One end 30T of the foil electrode 30 along the lamp axis C is connected to a power supply line (power supply rod) 60, and the power supply line 60 is connected to a power supply unit (not shown) provided outside.

[0025] The dielectric 50 is welded to the discharge tube 20 at a flange portion (hereinafter referred to as a weld portion) 52 protruding radially in a flange shape to form the inner tube of the double-tube type excimer lamp 10. The outer diameter of the weld portion 52 of the dielectric 50 is set according to the inner diameter D1 of the discharge tube 20.

[0026] like Figure 2 As shown in FIG. 1 , the foil electrode 30 is coaxially arranged with the discharge tube 20, and the dielectric 50 is also coaxially arranged with the discharge tube 20. Therefore, the foil electrode 30 is coaxially arranged in a state where the center position in the width direction and the thickness direction thereof coincides with the center position of the dielectric 50. Furthermore, the foil electrode 30 is arranged at a position symmetrical with respect to the tube axis C. Figure 1 to Figure 3 In the diagram, 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.

[0027] An outer electrode 40 is provided on 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 by the discharge generated in the discharge space S, for example, a film or plate having thermal conductivity and electrical conductivity. Here, the outer electrode 40 covers the outer surface 20S of the discharge tube 20 except the discharge surface 20D. The outer electrode 40 can be made of a film (such as an aluminum film) that reflects light including ultraviolet rays having a wavelength of 172 nm, for example.

[0028] When a high-frequency voltage (for example, a voltage in the range of several kV to more than ten 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 specified spectrum (for example, a wavelength of 172 nm) is radiated from the discharge space S.

[0029] The light emitted from the discharge space S is guided to the emission surface 20D side by reflection from the outer electrode 40 and the fiber effect based on the dielectric 50 and the discharge tube 20, and is emitted from the emission surface 20D. By arranging the irradiation object to face the emission surface 20D, light irradiation or ultraviolet irradiation treatment can be performed.

[0030] The size of the small spot irradiation type excimer lamp 10 can be set according to the use environment, etc. For example, the axial length (luminous length) of the discharge generated in the discharge tube 20 can be set in the range of 20 mm to 400 mm. In addition, the outer diameter of the discharge tube 20 can be set in the range of 5 mm to 30 mm, preferably in the range of 8 mm to 25 mm.

[0031] In consideration of preventing the discharge tube from being degraded by the excimer light and suppressing the increase in the discharge start voltage, the wall thickness of the discharge tube 20 may be set within a range of, for example, 0.8 mm to 1.5 mm.

[0032] In order to prevent insufficient illumination due to narrowing of the discharge space and unstable discharge due to expansion of the discharge distance, the discharge distance, i.e., the distance between the dielectric 50 and the inner diameter of the discharge tube 20, can be set in the range of 2 mm to 12 mm, preferably in the range of 3 mm to 10 mm.

[0033] The foil electrode 30 is formed as an extremely thin strip electrode whose thickness is suppressed relative to the electrode width. Here, the thickness of the foil electrode 30 is set to be less than 1 / 30, preferably less than 1 / 50, and more preferably less than 1 / 100 relative to the electrode width. Figure 2 and Figure 3 In FIG. 1 , the thickness of the foil electrode 30 is exaggerated.

[0034] For example, the thickness of the foil electrode 30 may be set within a range of 20 μm to 50 μm in consideration of current capacity, ease of manufacturing, and prevention of peeling from the dielectric 50. On the other hand, the width of the foil electrode 30 may be set within a range of 1.2 mm to 10 mm in consideration of current capacity, ease of manufacturing, and prevention of interruption of discharge light due to enlarged electrode area.

[0035] The electrode material of the foil electrode 30 can be formed of a metal or alloy with high conductivity. Also, it can be made of a material that is easy to be polished by electric field. Here, molybdenum or an alloy containing molybdenum is used.

[0036] Here, the dielectric 50 is made of a dielectric material (SiO 2 The thickness of the dielectric 50 can be set in the range of 0.1 mm to 2 mm, for example, in consideration of maintaining the limit of insulation and preventing the increase of the discharge start voltage.

[0037] like Figure 2 As shown, the dielectric 50 is formed into a flat shape along the tube axis C. In addition, the thickness of the dielectric 50 is substantially constant along the width direction (Y direction) of the foil electrode 30. Therefore, it can also be said that the dielectric 50 is composed of a quadrangular columnar portion having a substantially constant thickness along the width direction (Y direction) of the foil electrode 30 and semi-cylindrical portions integrally formed at both ends of the quadrangular columnar portion.

[0038] The dielectric 50 is flattened in the thickness direction (X direction) of the foil electrode 30 and is elongated in the width direction (Y direction) of the foil electrode 30. Figure 3 ) is smaller than the outer diameter W11 ( Figure 1 Therefore, the distance between the inner surface of the discharge tube and the outer surface of the dielectric along the thickness direction (X direction) of the foil electrode 30 is D21 ( Figure 3 ) is longer than the distance interval D11 ( Figure 1 ).

[0039] like Figure 1 , Figure 3 As shown, the dielectric 50 includes a portion (hereinafter referred to as a small diameter portion) 53 formed inside the discharge tube so as to extend toward the discharge space S side and a portion (hereinafter referred to as a large diameter portion) 55 formed outside the discharge tube so as to protrude from the fusion portion 52 toward the power supply line 60 side, and the fusion portion 52 is sandwiched between the small diameter portion 53 and the large diameter portion 55. The position of the connection portion 54 connecting the small diameter portion 53 and the fusion portion 52 of the dielectric 50 along the tube axis C direction corresponds to the end portion 30T of the foil electrode 30.

[0040] Figure 4 It is an enlarged cross-sectional view of the foil electrode 30 .

[0041] As described above, the foil electrode 30 is an electrode formed to be very thin relative to the width w of the foil electrode, and the thickness t of the foil electrode is suppressed to less than 1 / 30 relative to the width w. The foil electrode 30 has a flat portion 32 with a constant thickness (= t), and the foil electrode 30 has wedge-shaped portions 34A, 34B, and the front ends of the wedge-shaped portions 34A, 34B are thinned in a wedge shape from the width direction ends (the ends along the width direction) 32A, 32B of the flat portion 32 to the width direction ends (the ends along the width direction) E1, E2 of the foil electrode 30.

[0042] For example, the angles θ1 and θ2 (angle θ of the edge E) at the two ends E1 and E2 in the width direction of the foil electrode 30 can be set within a range of 2° to 15°, preferably within a range of 10° or less, by considering the difficulty of peeling caused by the gap generated in the boundary portion with the covered dielectric, the size of the cross-sectional area of ​​the flat portion corresponding to the current capacity, and the suppression of the temperature rise caused by the generation of Joule heat. In addition, the inclination angle of the cross section of the flat portion 32 can be set within a range of less than 2°. The angle θ can be set according to the following angle: when the cross section near the range of about 100 μm away from the edge E of the foil electrode 30 is magnified and observed, the thickness increases from the edge E of the foil electrode toward the flat portion 32. As a result, in the foil electrode 30, the edge-shaped edge E is formed on the entire electrode along the tube axis C direction.

[0043] The flat portion 32 is formed so that the center (central portion) in the width direction coincides with the tube axis C, and the wedge-shaped portions 34A and 34B are symmetrical with respect to the flat portion 32. In addition, regarding the wedge-shaped portions 34A and 34B, the width direction length d1 of the wedge-shaped portions 34A and 34B is set to be less than 0.2 with respect to the electrode width w (d1 / w) of the foil electrode 30. Here, the inclination angle θ of the cross section from the width direction ends of the wedge-shaped portions 34A and 34B toward the width direction ends 32A and 32B of the flat portion 32 is formed to be constant.

[0044] The flat portion 32 is formed to have a thickness that accounts for 70% or more of the maximum thickness T of the foil electrode 30. For example, the length d between the widthwise ends 32A and 32B of the flat portion 32 is set to be 0.6 or more relative to the electrode width w of the foil electrode 30 (d / w).

[0045] Figure 5 It is an enlarged cross-sectional view of the foil electrode 30 and the dielectric 50 covering the foil electrode 30 .

[0046] As described above, the dielectric 50 is flat along the tube axis C and has an oblong or oval (oval) cross section. The dielectric 50 has a substantially uniform cross-sectional shape in the range covering the foil electrode 30 along the tube axis (lamp axis) C.

[0047] The cross-sectional shape of the dielectric 50 is long oval or long circle. Figure 4 The arrangement and shape matching of the foil electrode 30 shown are cross-sectional shapes that reduce the difference in the distance from any surface of the foil electrode 30 to the outer surface 50S of the dielectric 50 (to the thickness of the foil electrode).

[0048] Here, the section M0 is defined as the central section (planar section) 50M0, and the section M0 has a planar (flat surface) outer surface 50S1 of a quadrangular columnar section that is substantially parallel to the flat section 32 of the foil electrode 30 and substantially perpendicular to the discharge surface 20D of the discharge tube 20. The section M1 is defined as the two end sections (curved section sections) 50M1, and the section M1 has a curved (semi-elliptical) outer surface 50S2 of a semi-cylindrical section that is convex from both ends of the central section 50M0 toward the outside in the electrode width direction (Y direction).

[0049] The quadrangular columnar portion is a columnar body whose cross section along the lamp diameter direction is a quadrilateral shape such as a square or a rectangle, and whose cross-sectional shape is the same along the tube axis C direction which is substantially parallel to the flat portion 32 of the foil electrode. The quadrangular columnar portion is a pair, and covers the vicinity of the center portion in the width direction of the foil electrode from both sides in the electrode thickness direction so that the thickness T2 is substantially constant.

[0050] The semi-cylindrical portion is a semi-cylindrical body whose cross section along the lamp diameter direction is approximately a semicircular shape such as a semi-ellipse, and whose cross-sectional shape is the same along the tube axis C. The semi-cylindrical portion is a pair, and covers the vicinity of the edge in the width direction of the foil electrode from both sides in the electrode width direction in a manner of surrounding the vicinity of the edge with the vicinity of the edge as the center, with a thickness T1 in the electrode width direction and a thickness T2 in the electrode thickness direction.

[0051] The boundary between the central portion (flat portion) 50M0 and the two end portions (curved portion) 50M1 of the dielectric 50 is located closer to the center (tube axis C) of the width direction of the foil electrode 30 than the two ends E1 and E2 of the foil electrode 30, preferably the width direction ends 32A and 32B of the flat portion 32, along the width direction (Y direction) of the foil electrode 30. That is, the length of the section M0 along the width direction (Y direction) of the foil electrode is set to be smaller than w, preferably smaller than d. In addition, the length of the section M1 is formed to be larger than T1.

[0052] As described above, the dielectric 50 that is welded to the discharge tube 20 to form a double tube lamp has a small diameter portion 53 and a large diameter portion 55. The outer diameter W11 (see FIG. 1 ) of the small diameter portion 53 along the width direction (Y direction) of the foil electrode 30 is Figure 1 ) and the outer diameter W21 along the thickness direction (X direction) (refer to Figure 3 ) are smaller than the outer diameter W12 of the large diameter portion 55 which has a circular cross section.

[0053] Here, the outer diameter W11 of the dielectric 50 along the width direction (Y direction) of the foil electrode 30 is set to be 3 / 4 or less, preferably 1 / 2 or less, of the inner diameter D1 of the discharge tube 20 .

[0054] According to the excimer lamp 10 of the present embodiment described above, since the dielectric 50 is configured to be flat, the light radiation efficiency is improved as a point irradiation type excimer lamp 10 .

[0055] That is, the flat dielectric 50 has a smaller cross-sectional area than a dielectric having a circular cross section, thereby ensuring the volume of the discharge space S. That is, the cross-sectional area of ​​the discharge space S is larger along the thickness direction (X direction) of the foil electrode 30 when viewed from the discharge surface 20D.

[0056] Therefore, it is possible to suppress the attenuation of the light reflected by the outer electrode 40 while being guided to the emission surface 20D along the tube axis C. This allows the excimer lamp 10 to be small but long in the axial direction, and the length of the discharge tube 20 along the tube axis C can be adjusted to be large and the illumination can be increased.

[0057] Furthermore, since the dielectric 50 is flat, uniform illumination distribution is achieved along the thickness direction (X direction) of the foil electrode 30. That is, in the electrode structure in which the foil electrode 30 is provided with the flat portion 32, the distance interval from the outer surface 50S of the dielectric 50, that is, the thickness along the thickness direction (X direction) of the foil electrode 30 is substantially constant along the width direction (Y direction) of the foil electrode 30.

[0058] Therefore, it is possible to suppress the occurrence of uneven discharge in the width direction (Y direction) of the foil electrode 30, and in particular suppress the reduction of illuminance near the center portion. This makes the illuminance distribution uniform and increases the area of ​​the discharge surface 20D (the volume of the discharge tube 20).

[0059] Furthermore, the diameter W11 of the small diameter portion 53 disposed in the discharge tube 20 of the dielectric 50, that is, disposed in the discharge space S, is smaller than the large diameter portion 55 outside the discharge space S. Thus, the volume of the discharge space S can be ensured to be large, and the attenuation of the light emitted by the discharge generated in the discharge space S while traveling toward the radiation surface 20D side due to the fiber effect of the dielectric 50 and the discharge tube 20 and the reflection of the outer electrode 40 is suppressed and guided.

[0060] On the other hand, the foil electrode 30 is formed with wedge-shaped portions 34A and 34B that are sharpened toward both ends E1 and E2 in the width direction, and the dielectric 50 is flat along the width direction (Y direction) of the foil electrode 30. Therefore, even if the area of ​​the discharge surface 20D (the volume of the discharge tube 20) is increased, the discharge start voltage can be set low by electric field concentration, and the lighting startability can be maintained in a good state.

[0061] Furthermore, due to the wedge-shaped portions 34A and 34B of the foil electrode 30, the foil electrode 30 is in close contact with the dielectric 50, and a gap is not easily generated at the boundary portion with the dielectric 50, and peeling is not easily generated. Furthermore, by forming the flat portion 32 on the foil electrode 30, the close contact between the foil electrode 30 and the dielectric 50 can be improved to suppress peeling. As a result, it is possible to suppress the attenuation of light during the period when it travels to the emission surface 20D side inside the dielectric 50 due to the fiber optic effect, and the illumination of light can be increased.

[0062] Such an excimer lamp 10 having the dielectric 50 can be manufactured by, for example, the following manufacturing method.

[0063] First, the power supply line is connected to the foil electrode by resistance welding or the like, and a glass tube as a dielectric coating material is inserted. After the foil electrode is inserted, the glass tube is evacuated, and then the dielectric coating material is heated from the outside to seal it with the foil electrode. At this time, the heating is adjusted so that the cross-sectional shape of the dielectric 50 described above is obtained.

[0064] For example, a dielectric having an oblong or oblong cross section can be formed by performing the following steps: rotating the glass tube while heating it with a burner or the like, thereby uniformly shrinking (reducing the diameter) the inner surface of the glass tube in the circumferential direction until it contacts the two ends (wedge-shaped portions) of the foil electrode, and shrinking the glass tube between the portions contacting the two ends (wedge-shaped portions) of the foil electrode in the thickness direction of the foil electrode to be integrated with the flat portion. Alternatively, a step of coating the dielectric or a step of cutting the glass tube may be performed.

[0065] A flange-shaped so-called abacus-shaped sealing portion is formed at a position of the glass tube corresponding to the electrode edge along the tube axis direction. Then, a discharge tube made of quartz glass or the like is formed with an exhaust pipe at one end and an insertion port at the other end, a dielectric sealed with foil electrodes is inserted into the discharge tube, and the insertion port of the discharge tube is welded to the abacus-shaped sealing portion.

[0066] While heating the entire discharge tube, the discharge tube is evacuated through the exhaust pipe to remove impurities. Then, after the discharge gas is sealed, the exhaust pipe is sealed and an outer electrode is arranged on the outer surface of the discharge tube. At this time, on the outer surface of the discharge tube, the area serving as the discharge surface is shielded, and the area where the outer electrode is arranged is irradiated with ultraviolet rays to perform surface treatment, and then the outer electrode is directly formed on the outer surface of the discharge tube by sputtering.

[0067] In the excimer lamp 10 of the present embodiment described above, the dielectric 50 is configured to be flat, but it may also be configured to be elliptical. That is, the dielectric 50 may be formed to have an elliptical cross section along the tube axis C. Furthermore, the dielectric 50 is not limited to being flat as a whole, but may be configured to be partially flat. For example, only a portion covering a portion of the inner electrode 30 may be flat.

[0068] The foil electrode 30 may be configured without the flat portion 32 and without the wedge-shaped portions 34A and 34B. The thickness of the end portion in the electrode width direction (Y direction) may be smaller than the thickness of the center portion.

[0069] The thickness T2 of the foil electrode 30 may be set in accordance with the area of ​​the discharge surface 20D of the discharge tube 20, i.e., the inner diameter D1, in consideration of the uniformity of the illuminance distribution along the thickness direction (X direction) of the foil electrode 30. For example, the thickness T2 may be set to be 1 / 200 or less of the inner diameter D1 of the discharge surface 20D.

[0070] Furthermore, in consideration of the lighting startability due to electric field concentration, the width W of the foil electrode 30 may be set according to the area of ​​the discharge surface 20D, i.e., the inner diameter D1 of the discharge tube 20. For example, the width W of the foil electrode 30 may be set to be less than 1 / 2, preferably less than 1 / 4 of the inner diameter D1 of the discharge surface 20D.

[0071] The structure of the outer electrode 40 may be an electrode structure other than an aluminum film, and may be configured so that light is reflected by providing a material or component capable of reflecting light instead of only the outer electrode 40. Furthermore, light may be reflected by a material or component other than the outer electrode 40. Instead of emitting ultraviolet rays from the emission surface, visible light emitted from discharge or a phosphor may be emitted.

Claims

1. An excimer lamp, which is a point irradiation type excimer lamp, characterized in that: The excimer lamp has: a discharge tube having a light emission surface formed at one end thereof; and a dielectric covering a foil electrode extending in a strip shape in the discharge tube, The dielectric has a flat shape corresponding to a width direction of the foil electrode.

2. The excimer lamp according to claim 1, characterized in that: The dielectric has outer surfaces that are substantially parallel along a width direction of the foil electrode.

3. The excimer lamp according to claim 1, characterized in that: The dielectric has a planar outer surface that is substantially perpendicular to the discharge surface.

4. The excimer lamp according to claim 1, characterized in that: The cross section of the dielectric is in the shape of an oblong circle or an oblong ellipse.

5. The excimer lamp according to claim 1, characterized in that: The dielectric has a small diameter portion formed inside the discharge tube and a large diameter portion formed outside the discharge tube. The diameter of the small diameter portion along the width direction and the thickness direction of the foil electrode is smaller than the diameter of the large diameter portion.

6. The excimer lamp according to claim 1, characterized in that: The foil electrode has a flat portion between both ends of the foil electrode in the width direction, the thickness of which is substantially constant in the width direction. The foil electrode is sharpened from both ends of the flat portion toward both ends of the foil electrode in the width direction.

7. The excimer lamp according to any one of claims 1 to 6, characterized in that: The foil electrode is arranged coaxially with the dielectric, A distance between the outer surface of the dielectric and the foil electrode along a thickness direction of the foil electrode is shorter than a distance between the outer surface of the dielectric and the foil electrode along a width direction of the foil electrode.

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