TWI912621B - excimer lamp - Google Patents

Abstract

[Problem] Suppressing discharge deviation in an excimer lamp with dielectric-coated foil electrodes. [Solution] In an excimer lamp 10 where a dielectric 50 covers the foil electrode 30, forming a discharge space S between the dielectric 50 and the discharge tube 20, the foil electrode 30 is covered by the dielectric 50 and coaxially arranged relative to the dielectric, which has an elongated elliptical or oblong cross-section. The dielectric 50 is coaxially arranged relative to the discharge tube 20.

Description

excimer lamp

This invention relates to excimer lamps, and more particularly to the structure of foil electrodes disposed within a discharge capacitor and the dielectric material covering the foil electrodes.

In an excimer lamp, excimer discharge occurs in the discharge space by applying a high-frequency voltage of several kV between a pair of electrodes. For example, in a dual-tube excimer lamp, two coaxial cylindrical tubes extending in the axial direction form the dual-tube configuration, and a discharge gas is sealed into the discharge space formed between the inner and outer tubes. Furthermore, by applying a high-frequency voltage between the electrodes disposed inside or on the wall of the inner tube (inner electrodes) and the electrodes on the outer surface of the outer tube (outer electrodes), discharge and luminescence are achieved.

When a large electrical current is supplied to the excimer lamp, the electrode easily peels off from the dielectric due to the difference in thermal expansion between the dielectric covering and the electrode. Therefore, the ends of the dielectric-covered foil electrode are formed into blade edges (see Patent 1). Electrolytic concentration occurs in the electrode edges, and because the electrolytic intensity is increased, it can be started by applying a lower voltage.

[Advanced Technology Literature]

[Patent Documents]

[Patent Document 1] Japanese Patent No. 5504095

By forming a blade-shaped edge near both ends of the foil electrode, the electrolytic intensity becomes excessively strong near the width edge of the foil electrode when the lamp is lit, causing a deviation in the circumferential direction of the discharging lamp within the discharge space. In particular, insufficient sealing with the dielectric covering the foil electrode may lead to peeling.

Therefore, in excimer lamps with dielectric-coated foil electrodes, it is necessary to suppress discharge deviation.

This invention relates to the shape of a dielectric material covering a foil electrode. An embodiment of this invention, an excimer lamp, includes: a foil electrode extending in a strip along the lamp axis; a dielectric material covering the foil electrode; and a tubular discharge capacitor forming a discharge space between the dielectric materials. Furthermore, the dielectric material is composed of a quadrangular prism-shaped portion with a substantially constant thickness along the width direction of the foil electrode, and semi-cylindrical portions integrally formed at both ends of the quadrangular prism-shaped portions.

Here, the "quadrilateral column" is a columnar body whose cross-section along the lamp diameter is approximately quadrilateral, such as a square or rectangle, and has the same cross-sectional shape along the lamp axis. This quadrilateral columnar part covers the foil electrode on both sides in the thickness direction. Similarly, the "semi-cylindrical part" is a semi-circular body whose cross-section along the lamp diameter is approximately semi-elliptical, and has the same cross-sectional shape along the lamp axis. This semi-cylindrical part covers the foil electrode on both sides in the width direction.

The dielectric's shape, as seen from its axial direction, is elongated elliptical or oblong. For example, the foil electrodes are arranged coaxially with respect to the dielectric, and the dielectric is arranged coaxially with respect to the discharge capacitor.

Here, "elongated ellipse" and "elliptical" refer to a cross-section with an elliptical shape. The term "elliptical" as used here includes an elongated ellipse or oblong shape with rounded ends and generally parallel straight lines inserted in between. Here, "elongated ellipse" is defined as a cross-sectional shape having generally parallel straight lines and becoming semi-elliptical from both ends.

The dielectric material's cross-section can be determined by the shape of the foil electrode. For example, the dielectric cross-section can be configured as an elongated ellipse or a long oval. The profile of the dielectric cross-section can be composed of a pair of straight profiles parallel to the width direction of the foil electrode, and semi-elliptical or semi-circular profiles connected to the ends of the straight profiles.

In the dielectric, the boundaries of the four corner columnar portions and the semi-cylindrical portions are positioned closer to the center of the electrode width than the two ends of the foil electrode in the width direction.

For example, when the distance along the thickness direction of the foil electrode from the foil electrode to the outer surface of the dielectric is set to T2, the width of the dielectric along the thickness direction of the foil electrode is set to W2, and the width of the dielectric along the width direction of the foil electrode is set to W1, and the distance along the aforementioned width direction of the foil electrode from the end of the foil electrode to the outer surface of the dielectric is set to T1, then the following equation is satisfied: W2 < W1.

T2 > T1.

The discharge capacitor can have various shapes. For example, a protruding portion with an inner diameter greater than the width of the dielectric material along the thickness direction of the foil electrode and smaller than the width direction of the dielectric material along the width direction of the foil electrode can be coaxially formed at one axial end of the discharge capacitor. Furthermore, to avoid obstructing the internal space of the protruding portion, the axial end of the dielectric material can be configured to partially contact the inner surface of the protruding portion.

According to this invention, discharge deviations can be suppressed in excimer lamps with dielectric-coated foil electrodes.

10: Excimer lamp

20: Discharge tube (discharge capacitor)

22S: Inside of the exhaust pipe

30: Foil Electrode

32: Flat area

32A, 32B: Width-direction ends of the flat portion

34A, 34B: Wedge-shaped portion

40: Outer electrode

50: Dielectric

50T: Front end

50S, 50S1, 50S2: Dielectric outer surface

54: Curved face

BL: Electrode-facing zone

E1, E2: Both ends in the width direction

M0, M1: Width direction range

C: Tube shaft (lamp shaft)

Figure 1 is a schematic cross-sectional view of the excimer lamp of this embodiment.

Figure 2 is a cross-sectional view of the excimer lamp in Figure 1 along line II-II.

Figure 3 is an enlarged view of the foil electrode in Figure 2.

Figure 4 is an enlarged view of the dielectric material shown in Figure 2.

The following diagram illustrates the excimer lamp of this embodiment.

Figure 1 is a schematic cross-sectional view of the excimer lamp of this embodiment. Figure 2 is a cross-sectional view of the excimer lamp of Figure 1 along line II-II.

The excimer lamp 10 has a tubular discharge tube (discharge container) 20 made of a dielectric material such as quartz glass, which is configured to have a circular cross-section along the tube diameter (lamp diameter). A rare gas such as xenon, or a mixture thereof, is sealed inside the discharge tube 20 as the discharge gas.

Inside the discharge tube 20, a foil electrode 30 extending in a strip along the tube axis (lamp axis) C is disposed. The foil electrode 30 is covered by a columnar dielectric 50, not exposed within the discharge space S, and is embedded within the dielectric 50.

The foil electrode 30 is coaxially positioned so that its center position in both the width and thickness directions matches the center position of the dielectric 50. Furthermore, the dielectric 50 is coaxially positioned relative to the discharge tube 20. Therefore, the foil electrode 30 is coaxially positioned relative to the discharge tube 20 and symmetrically positioned relative to the tube axis C. In Figure 2, the width direction of the foil electrode 30 is defined as the Y-direction, and the direction perpendicular to the Y-direction (thickness direction) is defined as the X-direction.

The outer electrode 40, located outside the discharge tube 20, is a structure in which a wire electrode made of conductive metal is wound along the outer surface of the discharge tube 20, arranged along the tube axis C and spaced at predetermined intervals. A power supply line 70 is connected to the end of the foil electrode 30 along the tube axis C, and also to an externally located power supply unit (not shown). Here, the region (electrode-facing region) where the outer electrode 40 and the foil electrode 30 face each other along the tube diameter (lamp diameter) and along the tube axis (lamp axis) C is denoted by the symbol BL, representing the axial length (luminous length) of discharge occurring within the discharge tube 20.

The foil electrode 30 and the outer electrode 40 are configured as anode and cathode, respectively. Furthermore, high frequency (e.g., several kHz to tens of MHz) and high voltage (e.g., several kV to tens of kV) are supplied to the discharge lamp 10 via the power supply line 70. This generates dielectric blocking discharge between the dielectric 50 covering the foil electrode 30 and the outer electrode 40, and radiates excimer light of a predetermined spectrum (e.g., wavelength 172 nm) from the main discharge space S.

The excimer lamp 10 in this embodiment is configured as a miniature excimer lamp. For example, the axial length (luminous length) of the discharge tube 20 can be set to a range of 20mm to 400mm. Furthermore, the outer diameter of the outer tube 20 can be set to a range of 5mm to 30mm, preferably 8mm to 25mm.

To prevent degradation caused by excimer laser light and to suppress the rise in discharge initiation voltage, the wall thickness of the discharge tube 20 can be set to, for example, the range of 0.8mm to 1.5mm. Furthermore, to address discharge instability caused by long discharge distances and to suppress insufficient illumination caused by short discharge distances, the inner diameter of the discharge tube 20 can be set to, for example, the range of 4mm to 28mm, preferably 6mm to 23mm.

The discharge distance, i.e., the distance between the inner diameter of the dielectric 50 and the discharge tube 20, can be set to a range of 2mm to 12mm, preferably 3mm to 10mm, to prevent insufficient illumination caused by a narrow discharge space and discharge instability caused by an increased discharge distance.

The foil electrode 30 is configured as an extremely thin strip electrode with limited thickness, relative to its width. Here, the thickness of the foil electrode 30 relative to its width is set to less than 1/30, preferably less than 1/50, and more preferably less than 1/100. Furthermore, the thickness of the foil electrode 30 is exaggerated in Figure 2.

For example, considering current capacity, ease of manufacturing, and preventing separation from the dielectric 50, the thickness of the foil electrode 30 can be set to a range of 20μm to 50μm. On the other hand, the width of the foil electrode 30, considering current capacity, ease of manufacturing, and preventing discharge light shielding caused by electrode hypertrophy, can be set to a range of 1.2mm to 10mm.

The electrode material of the foil electrode 30 can be formed from a metal or alloy with high conductivity. Alternatively, it can be made from a material that is easily electrolytically ground. Molybdenum or an alloy containing molybdenum can be used here.

Here, the dielectric 50 is composed of a dielectric material (such as _SiO2 ). The thickness of the dielectric 50, taking into account the limitations of maintaining insulation and preventing the rise of the discharge initiation voltage, can be set to, for example, a range of 0.1 mm to 2 mm.

At one end of the discharge tube 20, a protruding portion (hereinafter referred to as an exhaust pipe) 22 is formed. The exhaust pipe 22 is formed during the lamp manufacturing process, where the front end of a heated glass tube is deformed and narrowed, and a wafer tube smaller than the glass tube is fused together to form the exhaust pipe 22 integrally.

Figure 3 is an enlarged view of the foil electrode 30 in Figure 2.

As described above, the foil electrode 30 is an electrode formed with a thickness very thin relative to its width w, and the thickness t relative to the foil electrode width w is limited to 1/30 or less. The foil electrode 30 has a flat portion 32 with a constant thickness (=t), and wedge-shaped portions 34A and 34B that taper to their tips from both ends 32A and 32B in the width direction of the flat portion 32 to both ends E1 and E2 in the width direction of the foil electrode 30.

The wedge-shaped portions 34A and 34B of the foil electrode 30 are wedges with sharp edges. In other words, the foil electrode 30 is not sharpened from the center in the width direction to the edge, but rather from both ends 32A and 32B in the width direction of the flat portion 32 to both ends E1 and E2 in the width direction. Furthermore, the two ends E1 and E2 in the width direction are neither rolled nor thick; the ends E1 and E2 in the width direction of the foil electrode 30 are sharp, and the thickness towards the ends 32A and 32B in the width direction of the flat portion 32 increases at a predetermined angle.

For example, the angles θ1 and θ2 (angle θ at the edge E) at both ends E1 and E2 of the foil electrode 30 in the width direction can be set to a range of 2 degrees to 15 degrees, preferably 10 degrees or less, taking into account the difficulty of peeling caused by the gap between the foil electrode and the boundary portion of the coated dielectric, the size of the cross-sectional area of the flat portion corresponding to the current capacity, and the temperature rise caused by Joule heating. Furthermore, the bevel angle of the cross-section of the flat portion 32 can be set to less than 2 degrees. When observing a cross-section approximately 100 μm from the edge E of the foil electrode 30 under magnification, this angle θ can be set to the angle at which the thickness increases from the edge of the foil electrode 30 towards the flat portion 32. Therefore, on the foil electrode 30, a blade-shaped edge E is formed along the tube axis C throughout the entire electrode.

The flat portion 32 is formed so that its width-direction center (central portion) coincides with the tube axis C, and the wedge-shaped portions 34A and 34B are symmetrical in shape to the flat portion 32. Furthermore, the width-direction length d1 of the wedge-shaped portions 34A and 34B relative to the electrode width w of the foil electrode 30, i.e., d1/w, can be set to 0.2 or less. Here, the inclination angle θ of the cross-section from both ends of the flat portion 32 in the width direction to both ends 32A and 32B in the width direction is constant.

Furthermore, the flat portion 32 is formed to occupy at least 70% of the maximum thickness T of the foil electrode 30. For example, the length d between the two ends 32A and 32B of the flat portion 32 in the width direction, relative to the electrode width w of the foil electrode 30, i.e., d/W, is set to 0.6 or more.

This electrode shape improves the adhesion between the foil electrode 30 and the dielectric 50 to suppress peeling, and provides a small excimer lamp 10 with excellent start-up performance.

First, the electric field is concentrated because the edge E extending along the axis C of the foil electrode 30 is sharp. Therefore, discharge-initiation voltage can be suppressed while luminescence occurs. Furthermore, 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, which can suppress the discharge-initiation voltage to a lower level and makes it difficult for gaps to appear at the boundary with the coated dielectric 50, thus preventing peeling.

Furthermore, the foil electrode 30 is coaxially arranged relative to the dielectric 50 and the discharge tube 20, and the discharge distance, that is, the distance from the two edges E of the foil electrode 30 to the inner surface of the discharge tube 20, is equal. Therefore, light is emitted from the discharge tube 20 in a well-balanced manner.

On the other hand, compared to the foil electrode 30, forming the flat portion 32 improves the adhesion between the foil electrode 30 and the dielectric 50, thus suppressing peeling. In other words, by setting the flat portion 32 to a constant thickness t, a larger cross-sectional area can be ensured compared to the extremely thin foil electrode 30. In particular, the flat portion 32 occupies more than 60% of the foil electrode 30, so during lamp illumination, the flow of current through the larger cross-sectional area of the flat portion 32 suppresses Joule heating in the foil electrode 30.

Therefore, thermal expansion of the foil electrode 30 in both the thickness direction (X direction) and the width direction (Y direction) can be suppressed. That is, to ensure a large cross-sectional area, the foil electrode 30 does not need to be particularly long in the width direction, thus preventing excessive thermal expansion along the width direction. Furthermore, since the foil electrode 30 does not need to be particularly long in the width direction, excessive thermal expansion along the thickness direction can be prevented.

Furthermore, the wedge-shaped portions 34A and 34B formed from the two ends 32A and 32B of the flat portion 32 in the width direction toward the two ends E1 and E2 in the width direction, respectively, are wedge-shaped with sharp edges. Therefore, while concentrating the electrolytic intensity at the edge E of the foil electrode 30, it can suppress the peeling between the dielectric 50 and the foil electrode 30.

Furthermore, by forming wedge-shaped portions 34A and 34B with a constant tilt angle, it becomes easier to polish the surfaces of the wedge-shaped portions 34A and 34B by electrolytic polishing or the like. Therefore, peeling from the boundary portion of the dielectric 50 can be suppressed.

Furthermore, regarding the shape of the foil electrode 30, the foil electrode can be configured as a blade-edge shape, having a cross-section that smoothly slopes from the center towards both ends along the electrode width direction, and the foil electrode does not have a flat portion.

Figure 4 is an enlarged view of dielectric 50 shown in Figure 2.

The dielectric 50 of this embodiment matches the configuration and shape of the foil electrode 30 shown in FIG. 3, and has a cross-sectional shape that reduces the difference in distance (to the thickness of the foil electrode) from any surface of the foil electrode 30 to the outer surface 50S of the dielectric 50.

Specifically, the dielectric 50 has an elongated elliptical or oblong cross-section. In other words, the dielectric 50 has an elliptical cross-section. The dielectric 50, covering the area of the foil electrode 30 along the tube axis (lamp axis) C, has a substantially the same cross-sectional shape.

Here, as shown in Figure 4, in the cross-section of the dielectric 50, near the two ends E1 and E2 (ends 32A and 32B in the width direction of the flat portion 32) of the foil electrode 30, on the outer side, i.e., on the outer surface 50S2 of the dielectric 50, the contours on both sides are a pair of semi-elliptical shapes symmetrical in the width direction of the electrode. On the other hand, the cross-sectional contour facing the flat portion 32 (central portion) of the foil electrode 30 is a pair of straight contours symmetrical in the thickness direction of the electrode, such that the distance from the foil electrode 30 to the outer surface of the dielectric along the thickness direction (X direction) is approximately equal. The two ends of this straight profile are connected to the two ends of a semi-elliptical profile, forming a continuous elongated elliptical profile. The same profile is formed when the cross-section of dielectric 50 is set to an elongated ellipse.

Here, the section M0 is defined as the central section 52, and the section M0 has an outer surface 50S1 of a quadrangular prism-shaped portion that is substantially parallel to the flat portion 32 of the foil electrode 30. Furthermore, the section M1 is defined as a curved section 54, and the section M1 has an outer surface 50S2 of a convex semi-cylindrical portion that extends outward from both ends of the central section 52 in the electrode width direction (Y direction).

These four prismatic sections have a cross-section that is approximately square or rectangular along the lamp diameter direction, and are prismatic bodies with the same cross-sectional shape along the lamp axis. These four prismatic sections are a pair, covering the area near the center of the foil electrode in the width direction from both sides in the electrode thickness direction, thus making the thickness T2 constant.

Furthermore, the semi-cylindrical portion has a semi-circular cross-section along the lamp diameter direction that is approximately semi-elliptical or similar, and is a semi-cylindrical body with the same cross-sectional shape along the lamp axis. This semi-cylindrical portion is a pair, covering the vicinity of the edge of the foil electrode in the width direction from both sides, such that the vicinity of the edge is surrounded by a thickness T1 in the width direction and a thickness T2 in the thickness direction.

At each end of the electrode width of a pair of quadrangular prisms, a pair of semi-cylindrical portions are integrally formed. The boundaries of these quadrangular and semi-cylindrical portions are located closer to the center of the electrode width than at the ends of the foil electrode width.

The cross-sectional profile of the central portion 52 is equivalent to the straight section when it is set to an oblong or elongated ellipse. The cross-sectional profile of the curved portion 54, when set to a semi-ellipse, has a curvature that gradually increases towards the central portion 52; when set to a semicircle, it has a curvature that remains constant towards the central portion 52.

The boundaries of the central portion 52 and the curved portion 54 of the dielectric 50, along the width direction (Y direction) of the foil electrode 30, are preferably located closer to the center (tube axis C) of the foil electrode 30 in the width direction than the width direction ends 32A and 32B of the flat portion 32. That is, the length of the interval M0 along the width direction (Y direction) of the foil electrode is set to be smaller than w, preferably smaller than d. Furthermore, the length of the interval M1 is formed to be larger than T1.

Compared to a dielectric with a circular cross-sectional configuration, the cross-sectional profile of dielectric 50 can be as close as possible to the cross-sectional profile of foil electrode 30. Therefore, the distance from the vicinity of the width-direction ends E1 and E2 of foil electrode 30 to the outer surface 50S of the dielectric is not significantly different from the distance from the flat portion 32 to the outer surface 50S of the dielectric.

For example, the cross-sectional shape of the dielectric 50 can be set; along the thickness direction of the dielectric 50, i.e., the thickness direction of the foil electrode (X direction), the distance between the foil electrode 30 and the dielectric outer surface 50S1 of the central portion 52 of the dielectric 50 is set to T2; the width of the dielectric 50 along the thickness direction (X direction) of the foil electrode is set to W2; furthermore, the width of the dielectric 50 along the width direction, i.e., the width direction of the foil electrode (Y direction) of the dielectric 50 is set to W1; and the distance from both ends E1, E2 of the foil electrode 30 to the dielectric outer surface 50S2 along the width direction (Y direction) of the foil electrode is set to T1, to satisfy the following formula.

W2 < W1... (1)

T2>T1．．．． (2)

Furthermore, the cross-sectional shape of the dielectric 50 can be any shape other than an elongated ellipse, and can be determined by considering the shape of the foil electrode 30, etc. For example, as described above, when the foil electrode 30 has a blade-like edge with a smooth, sloping cross-section extending from the center towards both ends along the electrode width direction, the foil electrode 30 can have an elliptical cross-section. Furthermore, when the foil electrode 30 has a circular or steeply angled edge shape near both ends, the cross-section of the foil electrode 30 can be elongated.

The excimer lamp 10 having this dielectric 50 can be manufactured, for example, using the manufacturing method described below.

First, the power supply wire is connected to the foil electrode using impedance welding (solder resist) or similar methods, and then inserted into a glass tube that serves as the dielectric coating material. After inserting the foil electrode, a vacuum is evacuated from the glass tube. Then, the dielectric coating material is heated from the outside to fuse it with the foil electrode. During this process, heating adjustments are made to achieve the cross-sectional shape of the dielectric 50 as described above.

For example, by heating the glass tube with a burner or similar device while rotating it, the inner surface of the glass tube is uniformly contracted circumferentially until it contacts the two ends (wedge-shaped portions) of the foil electrode. By integrating the glass tube between the wedge-shaped portions and the foil electrode's contact points with the flat portion, a dielectric material with an elongated elliptical or oblong cross-section can be formed. Alternatively, the steps of applying the dielectric material or cutting the glass tube can be performed.

Along the axial direction of the glass tube, at a position corresponding to the electrode edge, a flange-shaped, abacus bead-shaped sealing portion is formed. Furthermore, the discharge tube, made of quartz glass or the like, has an vent pipe at one end and an insertion port at the other. The dielectric material of the fused foil electrode is inserted into the discharge tube, fusing the insertion port of the discharge tube with the abacus bead-shaped sealing portion.

While heating the entire discharge tube, a vacuum is simultaneously created through the vent pipe to remove impurities. Furthermore, after the venting gas is introduced, the vent pipe is sealed, and an external electrode is installed on the outside of the discharge tube.

Thus, according to this embodiment, in the excimer lamp 10 where the foil electrode 30 is covered by the dielectric 50, and a discharge space S is formed between the dielectric 50 and the discharge tube 20, the foil electrode 30 is coaxially arranged and covered relative to the dielectric 50, which has an elongated elliptical or oval cross-section. The dielectric 50 is coaxially arranged relative to the discharge tube 20.

The electrolytic intensity near the two ends E1 and E2 of the foil electrode 30 does not become excessive, and the excimer discharge extends along the dielectric outer surface 50S2 of the curved section 54, preventing discharge deviation along the lamp circumference. Furthermore, the two E1 and E2 points of the foil electrode 30 are sharp (wedge-shaped), and due to the concentrated electrolysis, it can be easily started and lit even with a relatively low voltage.

Furthermore, the two ends E1 and E2 of the foil electrode 30 in the width direction are preferably flat portions 32A and 32B, respectively, and are disposed closer to the outer surface 50S2 of the dielectric 50 than the central portion 52 of the dielectric 50; the flat portion 32 of the foil electrode 30 extends further along the width direction (Y direction) of the foil electrode than the central portion 52 of the dielectric 50. Therefore, good power-on performance can be maintained. In addition, the cross-sectional profile of the curved portion 54 is a semi-circle with gradually increasing curvature, so cracks caused by shrinkage of the dielectric 50 can be suppressed near the boundary between the central portion 52 and the curved portion 54.

Furthermore, the cross-section of dielectric 50 does not need to be strictly straight, as long as its outline runs along the electrode width direction; it can be slightly curved. For example, when the foil electrode 30 is smoothly formed into a blade edge shape from the center along the electrode width direction, a central portion with a matching cross-sectional outline can be formed. Additionally, in curved sections, the cross-sectional outline can be formed as a semi-circle.

Next, referring to Figure 1, the dielectric front end entering the vent pipe (protruding portion) formed at one end of the discharge tube will be explained.

The excimer lamp 10 has a tubular discharge tube 20, the end of which forms a vent pipe 22 with a hollow circular cross-section. Furthermore, the leading end portion 50T of the dielectric 50 extends along the tube axis C beyond the electrode-opposing region BL, reaching the vent pipe 22. The leading end portion 50T of the dielectric 50 is tapered, maintaining its cross-sectional shape as an elongated ellipse or oblong as shown in Figure 4.

The inner diameter of the exhaust pipe 22 is set to allow the dielectric 50 to partially enter the exhaust pipe 22. Specifically, the inner diameter of the exhaust pipe 22 is smaller than the electrode width length W1 of the dielectric 50 and larger than the electrode thickness length W2 of the dielectric 50. Therefore, the front end 50T of the dielectric 50 contacts the inner surface 22S of the exhaust pipe 22 in the portion along the electrode width direction (Y direction) (the outer dielectric surface 50S2 of the curved surface 54), and is coaxially held by the discharge tube 20, ensuring sufficient creepage distance and preventing creepage discharge near the front end 50T, which originates from the front end of the outer electrode 40 in the tube axis C direction.

On the other hand, the dielectric 50 has an elongated elliptical or oval cross-section at its front end 50T, as shown in Figure 4. The front end 50T of the dielectric 50 completely blocks the internal space of the vent pipe 22 without contact, creating a gap between the inner surface 22S of the vent pipe 22 and the portion along the electrode thickness direction (X direction) (the outer dielectric surface 50S1 of the central portion 52). Thus, it functions as a vent pipe, allowing for vacuum extraction or sealing of the discharge gas.

20: Discharge tube (discharge capacitor)

22S: Inside of the exhaust pipe

30: Foil Electrode

32: Flat area

34A, 34B: Wedge-shaped portion

40: Outer electrode

50: Dielectric

50S1, 50S2: Dielectric outer surface

C: Tube shaft (lamp shaft)

Claims (7)

An excimer lamp includes: a foil electrode extending in a strip along the lamp axis; a dielectric covering the foil electrode; and a tubular discharge container forming a discharge space between the dielectrics; the dielectric is composed of a quadrangular prism with a substantially constant thickness along the width direction of the foil electrode, and a semi-cylindrical portion integrally formed at both ends of the quadrangular prism; wherein, in the dielectric, the boundaries of the quadrangular prism and the semi-cylindrical portions are closer to the center of the electrode width than the two ends of the foil electrode along the width direction. The excimer lamp of claim 1, wherein the appearance shape seen from the axial direction of the aforementioned dielectric is an elongated ellipse or an oblong shape. For example, the excimer lamp of claim 2, wherein the cross-section of the aforementioned dielectric is an elongated ellipse or an oblong shape. As in claim 3, the profile of the cross-section of the aforementioned dielectric includes a pair of linear profiles parallel to the width direction of the aforementioned foil electrode, and a semi-elliptical or semi-circular profile respectively connected to the two ends of the aforementioned linear profiles. An excimer lamp includes: a foil electrode extending in a strip along the lamp axis; a dielectric covering the foil electrode; and a tubular discharge container forming a discharge space between the dielectric; the dielectric being composed of a quadrangular prism-shaped portion with a substantially constant thickness along the width direction of the foil electrode, and a semi-cylindrical portion integrally formed at both ends of the quadrangular prism-shaped portion; Wherein, when the distance from the aforementioned foil electrode to the outer surface of the aforementioned dielectric along the thickness direction of the aforementioned foil electrode is set to T2, the width of the aforementioned dielectric along the thickness direction of the aforementioned foil electrode is set to W2, and the width of the aforementioned dielectric along the width direction of the aforementioned foil electrode is set to W1, and the distance from the end of the aforementioned foil electrode to the outer surface of the aforementioned dielectric along the width direction of the aforementioned foil electrode is set to T1, then the following equations are satisfied: W2 < W1 ． ． ． ． (1) T2 > T1 ． ． ． ． (2) An excimer lamp includes: a foil electrode extending in a strip along the lamp axis; a dielectric covering the foil electrode; and a tubular discharge container forming a discharge space between the dielectrics; the dielectric is composed of a quadrangular prism-shaped portion with a substantially constant thickness along the width direction of the foil electrode, and a semi-cylindrical portion integrally formed at both ends of the quadrangular prism-shaped portion; wherein a protruding portion is coaxially formed on one axial end of the discharge container, the inner diameter of the protruding portion being larger than the width of the dielectric along the thickness direction of the foil electrode and smaller than the width of the dielectric along the width direction of the foil electrode; One axial end of the aforementioned dielectric partially contacts the inner surface of the aforementioned protruding portion in a manner that does not obstruct the inner space of the aforementioned protruding portion. An excimer lamp as described in any of claims 1 to 6, wherein the aforementioned foil electrodes are arranged coaxially with respect to the aforementioned dielectric; and the aforementioned dielectric is arranged coaxially with respect to the aforementioned discharge capacitor.