Excimer lamp

Abstract

The invention provides an excimer lamp which has good lighting start and durability. An excimer lamp (10) is provided with: a discharge tube (20); and a dielectric (50) that covers the foil electrode (30), and a main discharge space (S1) is formed between the discharge tube (20) and the dielectric (50). The dielectric (50) has: a sealing portion (54) that is sealed to the foil electrode (30); and a non-sealing section (52) that is not sealed to the foil electrode (30) and that is positioned further toward the tip side than the sealing section (54). An auxiliary discharge space (S2) is provided in the non-sealing portion (52).

Description

Technical Field

[0001] The present invention relates to an excimer lamp, and in particular to a structure of a discharge space of an excimer lamp. Background Art

[0002] In a double-tube excimer lamp, a light-emitting portion is formed by two coaxial cylindrical tubes extending in the axial direction, and a discharge gas is sealed in a discharge space formed between the inner tube and the outer tube. Furthermore, by applying a high-frequency voltage between an electrode (inner electrode) covered by the inner tube as a dielectric and an electrode (outer electrode) located on the outer surface of the outer tube, the discharge generated in the discharge space radiates excimer light such as ultraviolet rays.

[0003] For example, the following excimer lamp is known: in order to make the excimer lamp light up reliably, it has a starting auxiliary function of discharging at a voltage lower than the discharge start voltage (see Patent Document 1). Therefore, a discharge space for lighting start is formed in an inner tube through which an inner electrode extending along the lamp axis is inserted, and a gas having a lower starting voltage than that of the discharge space formed between the inner tube and the outer tube is sealed in the inner tube.

[0004] Furthermore, in an excimer lamp having an inner tube covered with a foil-shaped electrode as an inner electrode, there is known an excimer lamp in which the inner electrode and the inner tube are partially sealed (see Patent Document 2). Therefore, the inner electrode covered by the inner tube is provided with a portion sealed (sealed) by the inner tube and an unsealed portion, thereby forming an auxiliary discharge space for lighting and starting in which the inner electrode is exposed.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-4702

[0006] Patent Document 2: Japanese Patent Application Publication No. 2022-182685

[0007] If an auxiliary discharge space for lighting and starting is formed between the inner electrode and the inner tube along the lamp diameter direction, the starting auxiliary function may be reduced due to early electrode consumption due to sputtering. On the other hand, forming an auxiliary discharge space for lighting and starting in the entire range of the lamp axis direction will increase the temperature of the main discharge space due to the auxiliary discharge, thereby reducing the ultraviolet radiation efficiency. In particular, when a small excimer lamp (for example, the outer diameter of the discharge container is several mm to several tens of mm) is constructed, it is difficult to achieve both high-efficiency ultraviolet radiation and durability. Summary of the invention

[0008] Therefore, even in a small excimer lamp or the like, it is required to form a discharge space for lighting startup that has good lighting startup and durable performance.

[0009] An excimer lamp as one embodiment of the present invention includes: a dielectric that covers an inner electrode and includes a front end portion; and a discharge container that is fused to the dielectric to form a main discharge space. The discharge container may be formed in a tubular shape.

[0010] The portion of the dielectric covering the inner electrode is called a sealing portion. Here, "sealing" means that the dielectric (inner tube) made of glass or the like and the foil electrode are in close contact (closely fitted) with each other so that there is no gap between the foil electrode and the dielectric.

[0011] The dielectric of the present invention forms an auxiliary discharge space in a portion (herein, referred to as a non-sealed portion) closer to the end of the discharge container than the sealed portion covering the inner electrode. The auxiliary discharge space is formed in a portion different from the portion where the tubular dielectric melts and the hollow portion is buried to form a columnar block (for example, the portion where the front end of the inner electrode is buried) and the portion where the tubular dielectric melts and the hollow portion is buried to form a hemispherical block and the front end of the dielectric. This means that the dielectric has a portion that is not locally fused and a portion that is locally fused between the vicinity of the front end of the inner electrode and the front end of the dielectric.

[0012] The auxiliary discharge space may be formed as a space with a circular cross section, and the cross section area of ​​at least a part of the auxiliary discharge space may be larger than the cross section area of ​​the inner electrode. Furthermore, the auxiliary discharge space may be configured to face the outer electrode provided on the outer surface of the discharge container.

[0013] The inner electrode may be a foil-shaped electrode, and in a cross section along the electrode width direction of the inner electrode, at least a portion of the auxiliary discharge space may have a width along the electrode width direction greater than a width of the inner electrode.

[0014] When the inner electrode is a foil electrode, the width of the auxiliary discharge space along the electrode thickness direction of the inner electrode can be greater than the width of the sealing portion. The "width of the auxiliary discharge space" here corresponds to the width of the cross section along the electrode thickness direction of the space portion occupying most of the auxiliary discharge space.

[0015] Furthermore, when the inner electrode is a foil electrode, the distance between the outer surface of the dielectric and the inner surface of the discharge container along the electrode width direction of the inner electrode can be configured to be substantially constant along the lamp axis direction. The "distance" here corresponds to the width of the cross section along the electrode thickness direction of the space portion occupying most of the auxiliary discharge space.

[0016] The sealing portion may be configured to have an oblong or elliptical cross section, and may be configured such that the width of the sealing portion is substantially equal to the width of the non-sealed portion along the electrode width direction of the inner electrode. Furthermore, the thickness of the non-sealed portion may be configured such that the thickness of the sealing portion is smaller than the thickness of the sealing portion along the electrode thickness direction of the inner electrode.

[0017] The structure of the outer electrode provided on the outer surface of the discharge container is various, and may be configured to include a spiral portion obtained by spirally winding a conductive wire around the discharge container. For example, the auxiliary discharge space may not face the spiral portion.

[0018] A cylindrical portion obtained by cylindrically winding a conductive plate around the discharge container may be provided, the cylindrical portion is electrically connected to the spiral portion, and at least a part of the auxiliary discharge space is formed on the end side of the discharge container (the side where the outer electrode is not provided) relative to the cylindrical portion.

[0019] According to the present invention, the excimer lamp can be started well and have durable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic cross-sectional view of an excimer lamp along the electrode width direction.

[0021] Figure 2 This is a schematic cross-sectional view of an excimer lamp along the electrode thickness direction.

[0022] Figure 3 It is along Figure 1 Cross-sectional view along line III-III.

[0023] Figure 4 It is along Figure 1 A cross-sectional view taken along line IV-IV.

[0024] Figure 5 is an enlarged cross-sectional view of the foil electrode.

[0025] Figure 6 is with Figure 4 An enlarged cross-sectional view of the corresponding sealed portion of the foil electrode and the dielectric covering the foil electrode.

[0026] Description of symbols

[0027] 10: Excimer lamp; 20: discharge tube (outer tube); 30: foil electrode (inner electrode); 40: outer electrode; 50: dielectric (inner tube); 70: power supply rod (power supply line). DETAILED DESCRIPTION

[0028] Hereinafter, the excimer lamp according to the present embodiment will be described with reference to the drawings.

[0029] Figure 1 This is a schematic cross-sectional view of an excimer lamp along the electrode width direction. Figure 2 This is a schematic cross-sectional view of an excimer lamp along the electrode thickness direction. Figure 3 It is along Figure 1 Cross-sectional view along line III-III. Figure 4 It is along Figure 1 A cross-sectional view taken along line IV-IV.

[0030] The excimer lamp 10 has a tubular discharge tube (discharge vessel) 20 made of a dielectric material such as quartz glass, and is here formed into a discharge tube having a circular cross section along the tube diameter (lamp diameter) direction. A rare gas such as xenon or a mixed gas thereof is sealed in the discharge tube 20 as a discharge gas.

[0031] Inside the discharge tube 20, a foil electrode (hereinafter also referred to as an inner electrode) 30 is arranged in a strip shape extending along the tube axis (lamp axis) C. The foil electrode 30 is covered by a columnar dielectric 50 made of quartz glass or the like, and is not exposed to the discharge space S1, but is buried in the dielectric 50. That is, the foil electrode 30 is sealed (closed) to the dielectric 50 in a state of being sealed. A power supply line (power supply rod) 70 is connected to the end of the foil electrode 30 along the lamp axis C, and is connected to a power supply unit (not shown) provided outside.

[0032] The foil electrode 30 is coaxially arranged in a state where the center position of the foil electrode 30 in the width direction and the thickness direction coincides with the center position of the dielectric 50. Furthermore, the dielectric 50 is coaxially arranged with the discharge tube 20. Therefore, the foil electrode 30 is arranged at a position coaxial with the discharge tube 20 and at a position symmetrical with respect to the lamp axis C. Figure 2 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.

[0033] Here, the outer electrode 40 disposed on the outer surface 20S of the discharge tube 20 is a linear electrode portion (conductive wire) made of conductive metal wound along the outer surface of the discharge tube 20, and is arranged to be spirally wound along the lamp axis C and separated at predetermined intervals.

[0034] The outer electrode 40 is provided with such a spiral electrode portion (hereinafter referred to as the spiral portion 42) and conductive members (hereinafter referred to as the cylindrical members) 45A and 45B electrically connected to both ends 42T of the spiral portion 42. Here, the cylindrical members 45A and 45B are formed by winding a strip-shaped conductive plate covering a part of the outer surface 20S of the discharge tube 20 around the lamp axis C into a cylindrical shape. Here, the arrangement section L of the outer electrode 40 along the lamp axis C direction (hereinafter referred to as the outer electrode arrangement section) corresponds to the length of the inner electrode 30, and the entire range of the inner electrode 30 in the lamp axis C direction is opposite to the outer electrode 40 along the lamp diameter direction.

[0035] The excimer lamp 10 is formed as a double-tube type discharge lamp by fusing the enlarged diameter portion (hereinafter referred to as the welding portion) 56 of the dielectric 50 protruding in the radial direction in a flange shape with the discharge tube 20, and the dielectric 50 and the discharge tube 20 correspond to the inner tube and the outer tube of the double-tube type discharge lamp, respectively. A discharge space S1 (hereinafter referred to as the main discharge space) in which the above-mentioned discharge gas is sealed is formed between the dielectric 50 and the discharge tube 20. The power supply line 70 is covered by a portion (extension portion) 57 of the dielectric 50 that is formed to extend from the welding portion 56 to the outside of the discharge tube.

[0036] As described above, the dielectric 50 is sealed with the inner electrode 30, and on the other hand, a non-sealed portion 55 not sealed with the inner electrode 30 is provided between the front end 30T of the inner electrode 30 and the front end 50T of the dielectric 50. The non-sealed portion 55 can be divided into a welded portion 53, in which the hollow portion of the tubular dielectric of the welded portion 53 is filled by welding in the manufacturing process, and the front end 30T of the inner electrode 30 is buried (sealed) in the direction of the tube axis C; a welded portion 51, in which the hollow portion of the tubular dielectric of the welded portion 51 is filled by welding in the manufacturing process, and the welded portion 51 forms the front end 50T of the dielectric 50; and a portion (hereinafter referred to as a non-welded portion) 52 located between the welded portion 53 and the welded portion 51, in which the welded portion is not welded in the manufacturing process, and the dielectric remains tubular and the hollow portion is maintained.

[0037] The welded portion 51, the non-welded portion 52, and the welded portion 53 constituting the non-sealed portion 55 are continuously connected to a portion (hereinafter referred to as a sealed portion) 54 where the dielectric 50 and the inner electrode 30 are sealed. In addition, a discharge space (hereinafter referred to as an auxiliary discharge space) S2 for lighting startup is formed in the non-welded portion 52. The auxiliary discharge space S2 is formed at a position closer to the front end side of the dielectric 50, that is, the end 20T side of the discharge tube 20, than the front end 30T of the inner electrode 30 along the lamp axis C.

[0038] like Figure 3As shown in FIG. 1 , the auxiliary discharge space S2 has a circular cross-section near the center in the lamp axis direction, and the spatial distance (inner diameter) D1 along the width direction (Y direction) of the foil electrode 30 and the spatial distance (inner diameter) D2 along the thickness direction (X direction) of the foil electrode 30 are substantially the same. In addition, the wall thickness T10 along the width direction (Y direction) of the foil electrode 30 and the wall thickness T20 along the thickness direction (X direction) of the foil electrode 30 are also substantially the same. The inner surface of the auxiliary discharge space S2 is formed so that the size of its cross-sectional area (inner diameter) decreases smoothly from the center near the lamp axis C direction toward both ends (welded portions 51, 53).

[0039] Here, the non-welded portion 52 is formed closer to the end 20T of the discharge tube 20 than the outer electrode arrangement section L, and the auxiliary discharge space S2 is formed at a position deviated from the outer electrode arrangement section L along the lamp axis C as a whole.

[0040] The auxiliary discharge space S2 is in a reduced pressure state lower than the atmospheric pressure. In addition, a rare gas for reducing the voltage at the time of lighting startup may be sealed in the auxiliary discharge space S2 at a pressure lower than the atmospheric pressure.

[0041] A protruding portion (hereinafter referred to as an exhaust pipe) 22 is formed at one end 20T of the discharge tube 20. The exhaust pipe 22 is a portion formed during the lamp manufacturing process. Here, the end 20T of the discharge tube 20 is formed by reducing the diameter of the front end side of the glass tube as the raw material by heat deformation, and a tube smaller than the glass tube is welded, thereby integrally forming the exhaust pipe 22.

[0042] Here, the polarities of the foil electrode 30 and the outer electrode 40 are set to be anode and cathode. A high frequency (eg, several kHz to several tens of MHz) and a high voltage (eg, several kV to several tens of kV) are supplied to the excimer lamp 10 via the power supply line 70 .

[0043] When a high frequency voltage is applied, since the auxiliary discharge space S2 is in a decompressed state, discharge occurs first in the auxiliary discharge space S2 by a lighting starting voltage lower than that in the main discharge space S1. Then, part of the excimer light, i.e., ultraviolet light, emitted from the auxiliary discharge space S2 toward the lamp diameter direction is irradiated to the main discharge space S1 via the dielectric 50.

[0044] Furthermore, part of the ultraviolet rays generated in the auxiliary discharge space S2 and radiated toward the lamp axis C is transmitted to the expanded diameter portion 56 of the discharge tube 20 and the entire tube wall of the discharge tube 20 by the so-called fiber effect of repeatedly reflecting in the tube wall of the dielectric 50 (the boundary surface of the tube wall), and irradiates the ultraviolet rays toward the main discharge space S1. Here, excimer light (ultraviolet rays) of a predetermined spectrum (for example, a wavelength of 172 nm) is radiated from the main discharge space S1 by generating a dielectric barrier discharge.

[0045] The excimer lamp 10 of this embodiment is configured as a small excimer lamp. 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.

[0046] In consideration of suppressing the degradation of the discharge tube due to the excimer light and suppressing the increase of the discharge start voltage, the wall thickness of the discharge tube 20 can be set within a range of, for example, 0.8 mm to 1.5 mm.

[0047] In order to prevent insufficient illumination due to the narrowing of the discharge space and the instability of the discharge due to the expansion of the discharge distance, the discharge distance, i.e., the distance between the outer surface of the sealing portion 54 of the dielectric 50 and the inner surface of the discharge tube 20 in the outer electrode arrangement interval L can be set in the range of 2 mm to 12 mm, preferably in the range of 3 mm to 10 mm.

[0048] 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 , Figure 4 , Figure 6 In FIG. 1 , the thickness of the foil electrode 30 is exaggerated.

[0049] For example, the thickness of the foil electrode 30 may be set in the 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 in the 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.

[0050] 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.

[0051] 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.

[0052] Figure 5 It is an enlarged cross-sectional view of the foil electrode 30 .

[0053] As described above, the foil electrode 30 is an electrode formed to be very thin relative to the width w, and the thickness t of the foil electrode is suppressed to be less than 1 / 30 relative to the width w. The foil electrode 30 has a flat portion 32 with a constant thickness (= t), and has wedge-shaped portions 34A and 34B, and the front ends of the wedge-shaped portions 34A and 34B become thinner in a wedge shape from the width direction ends 32A and 32B of the flat portion 32 to the width direction ends E1 and E2 of the foil electrode 30.

[0054] Here, the wedge-shaped portions 34A and 34B of the foil electrode 30 are wedge-shaped and sharp until the edge. That is, the foil electrode 30 is not sharpened from the center to the edge in the width direction, but is sharpened from the ends 32A and 32B in the width direction of the flat portion 32 to the ends E1 and E2 in the width direction. Moreover, the ends E1 and E2 in the width direction of the foil electrode 30 are not rounded and have thickness, but the ends E1 and E2 in the width direction of the foil electrode 30 are sharpened, and the thickness increases at a constant inclination angle toward the ends 32A and 32B in the width direction of the flat portion 32.

[0055] 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.

[0056] 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.

[0057] 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).

[0058] With such an electrode shape, it is possible to provide a small excimer lamp 10 that improves the adhesion between the foil electrode 30 and the dielectric 50 to suppress separation and has excellent lighting startability.

[0059] First, the edge E of the foil electrode 30 extending along the lamp axis C is sharp, which generates electric field concentration. As a result, discharge light emission can be performed while suppressing the discharge start voltage to a low level. In addition, since the wedge-shaped portions 34A and 34B are wedge-shaped with sharp edges, the cross section near the edge E of the foil electrode 30 is linear in the axial direction, and the discharge start voltage can be suppressed to a lower level, and a gap is not likely to be generated at the boundary portion with the covered dielectric 50, and peeling is not likely to occur.

[0060] Furthermore, the foil electrode 30 is coaxially arranged with the dielectric 50, the discharge tube 20, and the outer electrode 40, and the distance between the edges E of the foil electrode 30 on both sides in a predetermined radial cross section within the outer electrode arrangement section L of the foil electrode 30 and the inner surface of the outer electrode 40 corresponding to the outer surface of the discharge tube 20, i.e., the inter-electrode distance, is equal, and the distance interval between the outer surface of the sealing portion 54 of the dielectric 50 and the inner surface of the discharge tube 20, i.e., the discharge distance, is equal. Therefore, light is radiated from the discharge tube 20 as a whole in a well-balanced manner.

[0061] On the other hand, by forming the flat portion 32 on the foil electrode 30, the adhesion between the foil electrode 30 and the dielectric 50 can be improved and peeling can be suppressed. That is, by providing the flat portion 32 with a constant thickness t, a relatively large cross-sectional area is ensured for the foil electrode 30 with an extremely thin thickness t. In particular, since the flat portion 32 occupies more than 60% of the foil electrode 30, during the lighting of the lamp, the current flows through the flat portion 32 with a relatively large cross-sectional area, thereby suppressing the generation of Joule heat in the foil electrode 30.

[0062] As a result, the thermal expansion of the foil electrode 30 in the thickness direction (X direction) and the width direction (Y direction) can be suppressed. That is, it is not necessary to make the foil electrode 30 particularly long in the width direction in order to ensure a larger cross-sectional area, and the increase of thermal expansion along the width direction can be prevented. In addition, it is not necessary to increase the thickness of the foil electrode 30, so the increase of thermal expansion along the thickness direction can be prevented.

[0063] Furthermore, by forming the wedge-shaped portions 34A and 34B with a constant inclination angle in the cross section, the surfaces of the wedge-shaped portions 34A and 34B can be easily polished by electrolytic polishing, etc. This can suppress the occurrence of peeling at the boundary portion with the dielectric 50 .

[0064] The foil electrode 30 may have a knife-edge shape with a cross section that smoothly slopes from the center toward both ends of the electrode along the electrode width direction and may be a foil electrode without a flat portion.

[0065] Figure 6 is with Figure 4 An enlarged cross-sectional view of the foil electrode 30 and the dielectric 50 covering the foil electrode 30 corresponding to the sealing portion 54 .

[0066] The dielectric 50 of this embodiment has Figure 5 The configuration and shape of the foil electrode 30 shown match the cross-sectional shape of, and 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).

[0067] The dielectric 50 is a flat material having a substantially constant thickness along the width direction (Y direction) of the foil electrode 30 (see Figure 4 , Figure 6 ), and is formed to be flat in the entire range of the arrangement section of the foil electrode 30 along the lamp axis C direction. 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.

[0068] The cross-sectional shape of the dielectric 50 is long oval or long circle. Figure 5 The configuration and shape of the foil electrode 30 shown match the cross-sectional shape of, and 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).

[0069] 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 substantially parallel to the flat section 32 of the foil electrode 30. 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 convex from both ends of the central section 50M0 toward the outside in the electrode width direction (Y direction).

[0070] The quadrangular columnar portion is a columnar body whose cross section along the lamp diameter direction is approximately a quadrilateral such as a square or a rectangle, and whose cross-sectional shape is the same along the lamp axis direction which is approximately 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 approximately constant.

[0071] 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 lamp axis direction. 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.

[0072] 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 two ends 32A and 32B of the flat portion 32 in the width direction. 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.

[0073] As described above, in the excimer lamp 10 of the present embodiment, the main discharge space S1 is formed between the discharge tube 20 and the dielectric 50 covering the foil electrode 30. In addition, the dielectric 50 is provided with: the sealing portion 54, which is sealed with the foil electrode 30; and the non-welded portion 52, which is located at the front end side of the sealing portion 54 and is not welded with the foil electrode 30. In addition, regarding the non-welded portion 52, the auxiliary discharge space S2 is provided in the non-welded portion 52 formed between the welded portion 51 and the welded portion 53. By forming the auxiliary discharge space S2 in the non-welded portion 52 of the dielectric 50 (inner tube), it is possible to provide an excimer lamp 10 having good lighting start-up performance and excellent durability.

[0074] First, as for the auxiliary discharge space S2, as described above, the cross section near the center is circular, and the discharge distances (inner diameters) D1 and D2 (D1≈D2) along the width direction (Y direction) and thickness direction (X direction) of the foil electrode 30 near the center of the non-welded portion 52 are larger than the widths W1 and W2 of the inner electrode 30. Therefore, even if the auxiliary discharge space S2 is arranged outside the outer electrode arrangement interval L along the lamp axis C, the discharge of the auxiliary discharge space S2 can be reliably generated first. This helps to improve the reliability of lighting start-up.

[0075] On the other hand, the front end 30T of the foil electrode 30 does not extend to the auxiliary discharge space S2, but is buried in the welded portion 53 of the dielectric 50 and is not exposed to the auxiliary discharge space S2. Therefore, the inner electrode 30 is not consumed by sputtering, and the lamp durability can be improved.

[0076] Since there is no sputtering phenomenon, the temperature rise of the main discharge space S1 caused by the auxiliary discharge can be prevented, and the uneven electric field intensity distribution and discharge unevenness of the main discharge during the lighting of the lamp can be prevented. This improves the uniformity of the illumination distribution. In addition, the circular cross-section of the auxiliary discharge space S2 also helps to suppress the generation of uneven discharge.

[0077] The structure of the dielectric 50 covering the foil electrode 30 can improve the ultraviolet radiation efficiency and prevent the main discharge from being uneven. That is, the outer diameter (width) W11 of the non-welded portion 52 is substantially equal to the outer diameter W1 of the sealed portion 54, so the discharge distance D10 between the non-welded portion 52 and the discharge tube 20 and the discharge distance D11 between the sealed portion 54 and the discharge tube 20 are substantially equal. By making the discharge distance substantially constant in the width direction (Y direction) of the foil electrode 30 along the lamp axis C, it is possible to suppress the occurrence of uneven discharge.

[0078] Furthermore, the wall thickness T20 of the non-welded portion 52 along the electrode thickness direction (X direction) is smaller than the wall thickness T2 of the sealed portion 54 along the electrode thickness direction (X direction). Therefore, even in the electrode thickness direction (X direction), the discharge in the auxiliary discharge space S2 does not hinder the discharge in the main discharge space S1, and the generation of non-uniform discharge can be suppressed.

[0079] The auxiliary discharge space S2 does not face the outer electrode 40 including the conductive member 45 in the lamp diameter direction, so the electric field strength in the auxiliary discharge space S2 is not too high, and the influence on the electric field strength distribution in the outer electrode arrangement section L, that is, the discharge non-uniformity, can be suppressed.

[0080] The inner electrode 30 may be configured as an inner electrode other than a foil electrode. For example, it may be configured as a rod-shaped electrode with a circular or rectangular cross section. Furthermore, the outer electrode 40 may be configured as an electrode structure other than a spiral structure, or may be configured as an electrode structure without cylindrical components at both ends of the outer electrode. The sealing portion 54 may be configured as a flat shape with an elliptical or oblong cross section or a shape other than an elliptical shape.

[0081] In addition, the auxiliary discharge space S2 may be arranged to face the outer electrode 40 along the lamp diameter direction (see Figure 140'T, 45'T). By setting the position of the auxiliary discharge space S2 forming the non-sealed portion 55 at a position that is partially opposite to the outer electrode 40 along the lamp diameter direction, the electric field intensity in the auxiliary discharge space S2 can be increased, that is, the auxiliary discharge is easy to perform. The electric field intensity distribution, the lighting start voltage based on the auxiliary discharge, etc. can be adjusted by adjusting the position of the auxiliary discharge space S2 forming the non-sealed portion 55 along the lamp axis C direction. Conversely, the position of the auxiliary discharge space S2 forming the non-sealed portion 55 or the configuration position of the two ends (cylindrical parts) of the outer electrode can also be adjusted according to the lighting start voltage. In this case, with respect to the outer electrode, its electrode structure can be set to the structure with a spiral portion, a conductive part, or other structures as described above. The appearance shape of the dielectric and the cross-sectional shape of the inner electrode are also arbitrary.

[0082] Such adjustment of the relationship between the position where the auxiliary discharge space is formed and the arrangement position of the outer electrode can meet the requirements of suppressing the applied voltage and improving the ultraviolet radiation efficiency and the requirement of radiating ultraviolet rays with a desired ultraviolet intensity with high accuracy in a small excimer lamp or the like.

Claims

1. An excimer lamp, characterized in that: The excimer lamp has: a dielectric covering the inner electrode and including a front end portion; and a discharge container, which is fused with the dielectric to form a main discharge space, The dielectric forms an auxiliary discharge space in a non-sealed portion located closer to an end portion of the discharge container than a sealed portion covering the inner electrode.

2. The excimer lamp according to claim 1, characterized in that: The auxiliary discharge space is circular in cross section. A cross-sectional area of ​​at least a portion of the auxiliary discharge space is larger than a cross-sectional area of ​​the inner electrode.

3. The excimer lamp according to claim 2, characterized in that: The inner electrode is a foil electrode, In a cross section along an electrode width direction of the inner electrode, a width of at least a portion of the auxiliary discharge space along the electrode width direction is greater than a width of the inner electrode.

4. The excimer lamp according to claim 2, characterized in that: The inner electrode is a foil electrode, Along the electrode thickness direction of the inner electrode, the width of the auxiliary discharge space is greater than the width of the sealing portion.

5. The excimer lamp according to claim 2, characterized in that: The inner electrode is a foil electrode, The distance between the outer surface of the dielectric and the inner surface of the discharge container along the electrode width direction of the inner electrode is substantially constant along the lamp axis direction.

6. The excimer lamp according to claim 2, characterized in that: The sealing portion has an oblong or elliptical cross section. Along the electrode width direction of the inner electrode, the width of the sealed portion is substantially equal to the width of the non-sealed portion.

7. The excimer lamp according to claim 2, characterized in that: The sealing portion has an oblong or elliptical cross section. Along the electrode thickness direction of the inner electrode, the thickness of the non-sealed portion is smaller than the thickness of the sealed portion.

8. The excimer lamp according to claim 1, characterized in that: The outer electrode provided on the outer surface of the discharge container has a spiral portion obtained by spirally winding a conductive wire around the discharge container. The auxiliary discharge space does not face the spiral portion.

9. The excimer lamp according to claim 8, characterized in that: The excimer lamp further comprises a cylindrical portion obtained by winding a conductive plate in a cylindrical shape around the discharge container, the cylindrical portion being electrically connected to the spiral portion. At least a portion of the auxiliary discharge space is formed at a position closer to an end portion of the discharge container than the cylindrical portion.

10. The excimer lamp according to claim 1, characterized in that: The auxiliary discharge space faces an outer electrode provided on an outer surface of the discharge container.

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