Excimer lamp

Abstract

To provide an excimer lamp in which generation of microcracks on an inner wall surface of an inner tube is suppressed.SOLUTION: The excimer lamp includes an arc tube including an outer tube extending in a tube axis direction and an inner tube extending in the tube axis direction and disposed in the outer tube, the outer tube and the inner tube being sealed at end portions in the tube axis direction, a light-emitting gas enclosed in a light-emitting space between the outer tube and the inner tube, an outer electrode disposed on an outer wall surface of the outer tube and having a net shape or a linear shape, and an inner electrode disposed on an inner wall surface of the inner tube and extending in a circumferential direction from one end to the other end. At an end portion of the inner electrode in the tube axis direction, a corner portion located at a circumferential end portion in the circumferential direction is located inside an outer edge region formed by virtually extending both a side of the inner electrode extending in the tube axis direction and a side of the inner electrode extending in the circumferential direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an excimer lamp. [Background technology]

[0002] Ultraviolet light has traditionally been used in the manufacturing process of semiconductors and liquid crystal panels, or to generate ozone for air purification. Excimer lamps are used as one of the light sources that emit ultraviolet light. Excimer lamps emit light by applying a voltage to a pair of electrodes located on the tube wall of the arc tube that correspond to the outside of the arc space, with a light-emitting gas sealed in the internal space of the arc tube (hereinafter sometimes referred to as the "light-emitting space") made of a dielectric.

[0003] The applicant has proposed an excimer lamp with a so-called double-tube structure, which has an arc tube including an outer tube and an inner tube (see Patent Document 1 below). As shown in Patent Document 1, in an excimer lamp with a double-tube structure, a voltage is applied to a light-emitting gas sealed in a light-emitting space sandwiched between the outer tube and the inner tube via an electrode arranged on the outer wall surface of the outer tube and an electrode arranged on the inner wall surface of the inner tube. The application of voltage causes a discharge (dielectric barrier discharge) in the light-emitting space, and the discharge excites atoms or molecules contained in the light-emitting gas, causing the excimer lamp to emit light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-96770 Summary of the Invention [Problem to be solved by the invention]

[0005] While the inventors were studying double-tube excimer lamps, they discovered that there were some areas on the surface of the arc tube of a prototype excimer lamp where diffused reflection of light was occurring, in order to clean the arc tube of the prototype excimer lamp that had accidentally become dirty.

[0006] Such diffuse reflection of light was confirmed on the inner wall surface of the inner tube. The diffuse reflection of light on the inner wall surface of the inner tube is thought to be due to the presence of tiny scratches (hereinafter referred to as "microcracks") on the inner wall surface that are too small to be detected by the naked eye. The inventors speculated that the microcracks were generated when the electrodes were placed on the inner wall surface. Hereinafter, the electrodes placed on the inner wall surface of the inner tube will be referred to as the "inner electrode."

[0007] As mentioned in Patent Document 1, the inventors have made the inner electrode from aluminum, which is a relatively soft metal, in order to prevent the inner wall surface of the inner tube from being damaged. However, due to the above-mentioned circumstances, the inventors have found that even when the inner electrode is made from aluminum, microcracks occur on the inner wall surface of the inner tube in which the inner electrode is disposed.

[0008] Because microcracks are extremely small scratches, they are not thought to have a significant effect on the normal lighting operation of an excimer lamp. However, if microcracks exist on the inner wall surface of the inner tube, it is expected that when the total lighting time of the excimer lamp is long (for example, 1,500 hours), the microcracks will become the starting point for problems such as cracks in the arc tube.

[0009] In view of the above, an object of the present invention is to provide an excimer lamp in which the occurrence of microcracks on the inner wall surface of the inner tube is suppressed. [Means for solving the problem]

[0010] The excimer lamp according to the present invention comprises: an arc tube including an outer tube extending in a tube axis direction, and an inner tube extending in the tube axis direction and disposed within the outer tube, wherein the outer tube and the inner tube are sealed at their ends in the tube axis direction; a light-emitting gas sealed in a light-emitting space sandwiched between the outer tube and the inner tube; an outer electrode arranged on an outer wall surface of the outer tube and having a net-like or linear shape; an inner electrode disposed on an inner wall surface of the inner tube and extending circumferentially from one end to the other end, The inner electrode is characterized in that, at an end portion in the tube axis direction, a corner portion located at the peripheral end portion in the circumferential direction is located inside an outer edge region formed by virtually extending both the side of the inner electrode extending in the tube axis direction and the side of the inner electrode extending in the circumferential direction.

[0011] The microcracks on the inner wall surface of the inner tube are presumed to occur when the inner electrode is inserted into the inner tube. The inventors presumed that when the inner electrode is inserted into the inner tube in the tube axis direction, microcracks are likely to occur due to friction between the corners located at the peripheral end and the inner wall surface of the inner tube, particularly at the end of the inner electrode in the tube axis direction.

[0012] Although details will be described later in the "Mode for Carrying Out the Invention" section, the corners of the inner electrode are positioned so that they are likely to come into contact with the inner wall surface of the inner tube when the inner electrode is inserted into the inner tube. In contrast, in the above configuration, the corners are positioned inside the outer edge region of the inner electrode, so that the corners are less likely to come into contact with the inner wall surface of the inner tube when the inner electrode is inserted into the inner tube. This suppresses the occurrence of microcracks on the inner wall surface of the inner tube when the inner electrode is inserted into the inner tube.

[0013] In other words, when comparing the case where the corners of the inner electrode are located inside the outer edge region with the case where the corners have a shape that matches the outer edge region, the former case makes it less likely for the corners to come into contact with the inner wall surface of the inner tube, reducing the number of microcracks that occur on the inner wall surface of the inner tube.

[0014] As described above, even when the inner electrode is made of relatively soft aluminum, microcracks were observed on the inner wall surface of the inner tube. However, it is surprising that the occurrence of microcracks in the inner tube can be suppressed by positioning the corners of the inner electrode more inward than the outer edge region through a simple process such as chamfering. Note that the method for forming the corners is not limited to chamfering. Specific examples of corners will be described later.

[0015] In the above excimer lamp, The inner electrode may be arranged in a plurality of regions in the circumferential direction of the inner wall surface of the inner tube.

[0016] When multiple inner electrodes are inserted into the inner tube, the number of positions on the inner wall surface of the inner tube that come into contact with the corners of the inner electrode increases, making microcracks more likely to occur. In contrast, with the above configuration, the corners of the inner electrode are located inside the outer edge region of the inner electrode, making it less likely that the corners will come into contact with the inner wall surface of the inner tube. Therefore, the above configuration is advantageous in that it can suppress the occurrence of microcracks even when multiple inner electrodes are inserted into the inner tube.

[0017] In the above excimer lamp, The corners of the inner electrode may have a linear chamfered shape.

[0018] In addition, in the above excimer lamp, The corners of the inner electrode may be chamfered in an arc shape.

[0019] Furthermore, in the above excimer lamp, The corner of the inner electrode may be shaped to be spaced apart from the inner wall surface of the inner tube.

[0020] As described above, by constructing the inner electrode from aluminum, the inner wall surface of the inner tube is less likely to be damaged. Considering that the corners of the inner electrode are located inside the outer edge region, which suppresses microcracks, the above configuration can be said to be less likely to damage the inner wall surface of the inner tube than conventional excimer lamps such as those described in Patent Document 1. In other words, the present invention is not limited to the inner electrode being made from aluminum. However, the inner electrode may be made from aluminum in order to further reduce the risk of damaging the inner wall surface of the inner tube. [Effects of the Invention]

[0021] According to the present invention, an excimer lamp is provided in which the occurrence of microcracks on the inner wall surface of the inner tube is suppressed. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of an excimer lamp according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along a plane different from that of FIG. 1. [Figure 3] FIG. 2 is a perspective view schematically showing how the inner electrode is inserted into the arc tube. [Figure 4] 3 is a diagram schematically illustrating the configuration of an inner electrode. [Figure 5] 5 is an enlarged view of a portion of the inner electrode shown in FIG. 4. [Figure 6] 4 is a diagram showing another example of the configuration of the inner electrode, following FIG. 3. [Figure 7] 8 is a diagram showing a schematic configuration of the inner electrode according to FIG. 7, following FIG. 4. [Figure 8] 8 is an enlarged view of a portion of the inner electrode according to FIG. 7. [Figure 9] 2 is a plan view of the excimer lamp in FIG. 1 as viewed from the Y direction. [Figure 10] FIG. 10 is a plan view showing another example of the configuration of the outer electrode, following FIG. 9. [Figure 11] 4 is a diagram showing another example of the configuration of the inner electrode, following FIG. 3. [Figure 12] 12 is a diagram schematically showing the configuration of the inner electrode according to FIG. 11. [Figure 13] 12 is a diagram schematically illustrating a state in which the inner electrode according to FIG. 11 is inserted into an inner tube. [Figure 14] 1, and shows another modified example of the excimer lamp. DETAILED DESCRIPTION OF THE INVENTION

[0023] An embodiment of an excimer lamp according to the present invention will be described below with reference to the drawings. Note that the drawings are all schematic illustrations, and the dimensional ratios and numbers in the drawings do not necessarily correspond to the actual dimensional ratios and numbers.

[0024] [First embodiment] 1 and 2 are cross-sectional views showing examples of the configuration of an excimer lamp according to the present invention, and each drawing corresponds to a cross-sectional view cut along a different plane. As shown in Fig. 1 and Fig. 2, the excimer lamp 1 includes an arc tube 3, an inner electrode 5, and an outer electrode 7.

[0025] In the following explanation, an XYZ coordinate system will be referenced, with the tube axis direction of the arc tube 3 defined as the X direction and the plane perpendicular to the X direction defined as the YZ plane. Using this definition, Fig. 1 corresponds to a cross-sectional view of the excimer lamp 1 along the YZ plane, and Fig. 2 corresponds to a cross-sectional view of the excimer lamp 1 along the XZ plane.

[0026] In the following description, for example, when a direction is expressed and a distinction is made between positive and negative directions, it is described with a positive or negative sign, such as "+X direction" and "-X direction." When a direction is expressed without distinguishing between positive and negative directions, it is simply described as "X direction." In other words, in this specification, when simply referring to "X direction," it includes both "+X direction" and "-X direction." The same applies to the Y direction and the Z direction.

[0027] As shown in Figures 1 and 2, the arc tube 3 includes an outer tube 11 and an inner tube 12, and has a double-tube structure. As shown in Figure 1, the inner tube 12 is disposed within the outer tube 11, and the outer tube 11 surrounds the periphery of the inner tube 12. Typically, the outer tube 11 and the inner tube 12 are disposed coaxially. Both the outer tube 11 and the inner tube 12 are sealed at their end positions in the X direction, and a base (not shown) is disposed at these end positions. A predetermined luminous gas is sealed in the space sandwiched between the outer tube 11 and the inner tube 12 (hereinafter referred to as the "luminous space 20") at a pressure of, for example, 10 kPa to 100 kPa.

[0028] The outer tube 11 and the inner tube 12 are made of a dielectric material such as quartz glass, for example.

[0029] For example, the outer diameter of the outer tube 11 is 25 mm to 40 mm, and the outer diameter of the inner tube 12 is 10 mm to 26 mm. The length of both in the X direction is 100 mm to 1600 mm. As an example, the outer diameter of the outer tube 11 is 40 mm, the outer diameter of the inner tube 12 is 16 mm, and the length of both in the X direction is 1200 mm. As an example, the thickness of the outer tube 11 is 2 mm, and the thickness of the inner tube 12 is 1 mm. In this case, the width in the radial direction of the ring-shaped light-emitting space 20 is 11 mm.

[0030] FIG. 2 schematically illustrates the propagation of ultraviolet light L1 emitted by the excimer lamp 1. As shown in FIG. 2, the ultraviolet light L1 is extracted to the outside of the excimer lamp 1 through the outer tube 11. Therefore, from the viewpoint of reducing attenuation of the ultraviolet light L1 due to absorption by the material (typically quartz glass) constituting the outer tube 11, the thickness of the outer tube 11 is preferably 2 mm or less. On the other hand, from the viewpoint of ensuring resistance to the gas pressure of the enclosed light-emitting gas, the thickness of the outer tube 11 is preferably 1 mm or more. Like the thickness of the outer tube 11, the thickness of the inner tube 12 is also preferably 1 mm or more.

[0031] As shown in Fig. 1, the inner electrode 5 is disposed on the inner wall surface 12a of the inner tube 12. Furthermore, as shown in Fig. 1, the inner electrode 5 extends from one end 5a to the other end 5b in the circumferential direction of the inner tube 12. In this embodiment, the inner electrode 5 is disposed in multiple regions in the circumferential direction of the inner wall surface 12a of the inner tube 12, as shown in Fig. 1. In other words, the excimer lamp 1 according to this embodiment has multiple inner electrodes 5.

[0032] From the viewpoint of increasing the light extraction efficiency of the excimer lamp 1, the inner electrode 5 is preferably made of a material that is reflective to the ultraviolet light L1. As an example, the inner electrode 5 is a plate-shaped member made of aluminum. The inner electrode 5 may also be made of a metal material such as titanium or stainless steel. The thickness of the inner electrode 5 is, for example, 0.2 mm to 1.0 mm, and is, for example, 0.5 mm. The plate-shaped member that makes up the inner electrode 5 is elastically deformable.

[0033] Fig. 3 is a perspective view that schematically shows how the inner electrode 5 is inserted into the arc tube 3. As shown in Fig. 3, the inner electrode 5 is inserted into the arc tube 3 in the X direction. Fig. 4 is a diagram that schematically shows the configuration of the inner electrode 5. For convenience of illustration, Fig. 4 shows the configuration of the inner electrode 5 in a plan view. As shown in Figs. 3 and 4, the inner electrode 5 has corners 6 located at the circumferential end in the circumferential direction at the end of the inner electrode 5 in the X direction.

[0034] When the inner electrode 5 is inserted into the arc tube 3 (see FIG. 3), the inner electrode 5 is inserted into the arc tube 3 in a state in which it is elastically deformed so as to conform to the shape of the inner wall surface 12a of the inner tube 12. Therefore, when the inner electrode 5 is inserted into the arc tube 3, an elastic force is generated in the inner electrode 5 in a direction toward the inner wall surface 12a of the inner tube 12. In other words, it can be said that the corners 6 of the inner electrode 5 are located in positions that make them likely to come into contact with the inner wall surface 12a of the inner tube 12 when the inner electrode 5 is inserted into the arc tube 3.

[0035] 4, the corners 6 are located inside an outer edge region A1 formed by imaginary extensions of both a side 5x extending in the X direction of the inner electrode 5 and a side 5r extending in the circumferential direction of the inner electrode 5. Therefore, as shown in FIG. 3, when the inner electrode 5 is inserted into the arc tube 3, the corners 6 are less likely to come into contact with the inner wall surface 12a. This prevents microcracks from occurring on the inner wall surface 12a of the inner tube 12 when the inner electrode 5 is inserted into the arc tube 3.

[0036] More specifically, since the corners 6 of the inner electrode 5 are located inside the outer peripheral region A1, the corners 6 are less likely to come into contact with the inner wall surface 12a than when the corners 6 have a shape that matches the outer peripheral region A1. In other words, when comparing the former and the latter, the number of microcracks that occur on the inner wall surface 12a of the inner tube 12 is reduced in the former.

[0037] Fig. 5 is an enlarged view of a portion of the inner electrode 5 shown in Fig. 4. As shown in Fig. 5, in this embodiment, the corners 6 of the inner electrode 5 have a linearly chamfered shape. More specifically, the corners 6 include a linear portion 6a connecting the sides 5x and 5r. The length of the linear portion 6a is preferably 2 mm to 4 mm.

[0038] It should be noted that, when the inner electrode 5 is inserted into the inner tube 12, friction may occur between the junction between the straight portion 6a and the side 5x and the inner wall surface 12a of the inner tube 12. In view of this, as shown in FIG. 5, the angle θ1 between the straight portion 6a and the side 5x is preferably an obtuse angle. As a specific example, the angle θ1 is preferably 100° to 170°, more preferably 125° to 145°, and particularly preferably 135°. By setting the angle θ1 to an obtuse angle, the occurrence of microcracks on the inner wall surface 12a of the inner tube 12 can be more suitably suppressed than when the corner portion 6 has a shape that coincides with the outer edge region A1. The same applies to the angle θ2 between the straight portion 6a and the side 5r.

[0039] The connecting portion between the straight line portion 6a and the side 5x may be arc-shaped, as may the connecting portion between the straight line portion 6a and the side 5r.

[0040] 6 is a diagram showing another example of the configuration of the inner electrode 5, following Fig. 3, and Fig. 7 is a diagram showing a schematic configuration of the inner electrode 5 according to Fig. 7, following Fig. 4. Fig. 8 is a diagram showing an enlarged view of a part of the inner electrode 5 according to Fig. 7. As shown in Figs. 6 to 8, the corners 6 have an arc-shaped chamfered shape, and may also have a rounded shape.

[0041] 8, as described with reference to Fig. 3, the corners 6 are located inside the outer edge region A1, so that the corners 6 are less likely to come into contact with the inner wall surface 12a when the inner electrode 5 is inserted into the arc tube 3. This prevents microcracks from occurring on the inner wall surface 12a of the inner tube 12 when the inner electrode 5 is inserted into the arc tube 3.

[0042] 8, corner 6 is formed by a circular arc 6b connecting side 5x and side 5r. Preferably, the length d1 in the X direction of the region where arc 6b is formed is set to 2 mm to 5 mm.

[0043] The method for forming the corners 6 of the inner electrode 5 is not particularly limited, and may be, for example, cutting or laser irradiation. In this specification, the term "chamfered shape" refers to a shape in which the corners 6 are chamfered and a new surface is created in the chamfered area. However, as long as the corners 6 have the above-mentioned chamfered shape, the method for forming the corners 6 of the inner electrode 5 is not limited.

[0044] The surface of the inner electrode 5 may be plated with a metal material such as zinc, chromium, or nickel.

[0045] The inner electrode 5 is fixed by an elastic member (not shown) that presses the inner electrode 5 against the inner wall surface 12a of the inner tube 12. As the elastic member, a metal spring or the like can be used.

[0046] As shown in FIGS. 1 and 2, the outer electrode 7 is disposed on the outer wall surface 11a of the outer tube 11. FIG. 9 is a plan view of the excimer lamp 1 shown in FIG. 1 as viewed from the Y direction. As shown in FIG. 9, the outer electrode 7 may have a mesh shape. When the outer electrode 7 has a mesh shape, ultraviolet light L1 is extracted to the outside of the excimer lamp 1 through gaps between the outer electrodes 7 (see also FIG. 2). Note that in FIG. 9, the line width constituting the outer electrode 7 is shown as being relatively large compared to the size of the gap between adjacent electrode wires, but this is merely for convenience of illustration. In reality, from the viewpoint of minimizing the degree of obstruction of the progression of ultraviolet light L1, it is preferable to ensure that the dimension of the gap between adjacent electrode wires is as large as possible relative to the line width constituting the outer electrode 7.

[0047] 10 is a plan view showing another example of the configuration of the outer electrode 7, following FIG. 9. As shown in FIG. 10, the outer electrode 7 may have a linear shape. Although the extension direction of the outer electrode 7 intersects with the X direction in FIG. 10, this extension direction is arbitrary. As another example, the outer electrode 7 may have a shape that extends in the X direction, or may have a spiral shape.

[0048] As an example, the outer electrode 7 has a cylindrical shape when viewed in the X direction, and is disposed on the outer wall surface 11a of the outer tube 11 by inserting the arc tube 3 in the X direction. The outer electrode 7 can be formed by attaching a mesh of metal wires, by attaching conductive tape to the outer wall surface 11a, or by applying a conductive paste to the outer wall surface 11a by screen printing and then firing the paste, or the like.

[0049] As shown in FIG. 2, a power supply 40 is connected to each of the inner electrode 5 and the outer electrode 7. As an example, the outer electrode 7 is connected to the power supply 40 via bases (not shown) made of a conductive material and arranged at both ends of the arc tube 3. The inner electrode 5 is also connected to the power supply 40 by a power supply line that passes through a through-hole formed in the base. In this embodiment, the multiple inner electrodes 5 are all at the same potential. When a high-frequency AC voltage of, for example, about 10 kHz to 100 kHz is applied from the power supply 40 between the inner electrode 5 and the outer electrode 7, ultraviolet light L1 is generated in the light-emitting space 20. As an example, the input power is 20 W to 2000 W, and the input voltage is about 5 kV to 10 kV.

[0050] The wavelength of the ultraviolet light L1 is determined by the type of luminescent gas. For example, when the luminescent gas containing Kr and Cl2 is sealed in the luminescent space 20, ultraviolet light L1 having a peak wavelength near 222 nm is obtained. However, the present invention is not limited to the type of luminescent gas sealed in the luminescent space 20. For example, the luminescent gas may contain Xe.

[0051] In view of the fact that the high voltage is applied between the inner electrode 5 and the outer electrode 7, it is preferable that the outer electrode 7 is connected to the ground side of the power supply 40 and that the inner electrode 5 has a higher potential in absolute value than the outer electrode 7. This makes it possible to prevent electric shock to operators and other objects outside the excimer lamp 1 and to prevent electric leakage to other objects.

[0052] The inventors fabricated an excimer lamp 1 according to the above embodiment in which the corners 6 of the inner electrode 5 were positioned inside the outer edge region A1 of the inner electrode 5 (see FIG. 4, etc.), and confirmed that this suppressed the occurrence of microcracks on the inner wall surface 12a of the inner tube 12 compared to when the corners 6 were shaped to coincide with the outer edge region A1. In other words, it was found that the excimer lamp 1 according to the above embodiment suppressed the occurrence of microcracks on the inner wall surface 12a of the inner tube 12.

[0053] In view of this, it is presumed that even when the corner 6 has an arc-shaped chamfered shape, as described with reference to Figure 8, the occurrence of microcracks on the inner wall surface 12a of the inner tube 12 is suppressed.

[0054] Furthermore, when the excimer lamp 1 is turned on, the arc tube 3 expands due to heat generation, and when the excimer lamp 1 is turned off, the arc tube 3 contracts. This is also true for the inner electrode 5. If the thermal expansion coefficients of the arc tube 3 and the inner electrode 5 differ, the inner electrode 5 moves relative to the arc tube 3 in the X direction when the arc tube 3 expands or contracts. In other words, due to the difference in the thermal expansion coefficients of the arc tube 3 and the inner electrode 5, friction occurs, albeit in a very small area, between the inner wall surface 12a of the inner tube 12 and the inner electrode 5 during the turning on and off of the excimer lamp 1. In contrast, in the excimer lamp 1, the corners 6 of the inner electrode 5 are located inside the outer edge region A1 of the inner electrode 5, so that the corners 6 are less likely to come into contact with the inner wall surface 12a of the inner tube 12. In other words, by configuring the corners 6 as described above, it is possible to suppress the occurrence of microcracks not only when the inner electrode 5 is inserted into the arc tube 3, but also when the excimer lamp 1 is in use.

[0055] [Variations] Modified examples of the excimer lamp 1 will now be described.

[0056] <1> Fig. 11 is a diagram showing another example of the configuration of the inner electrode 5, following Fig. 3, and Fig. 12 is a diagram schematically showing the configuration of the inner electrode 5 according to Fig. 11. As shown in Figs. 11 and 12, the corners 6 may be formed by bending the inner electrode 5 inward.

[0057] 13 is a diagram schematically illustrating a state in which the inner electrode 5 according to FIG. 11 is inserted into the inner tube 12. The outer tube 11 is not shown in FIG. 13. In this modification, the corners 6 of the inner electrode 5 are shaped to be spaced apart from the inner wall surface 12a of the inner tube 12, as shown in FIG.

[0058] In this modification as well, the corners 6 are located inside the outer edge region A1 (see FIG. 12), so that the corners 6 are less likely to come into contact with the inner wall surface 12a when the inner electrode 5 is inserted into the arc tube 3. This prevents microcracks from occurring on the inner wall surface 12a of the inner tube 12 when the inner electrode 5 is inserted into the arc tube 3.

[0059] <2> Fig. 14 is a diagram showing another modified example of the excimer lamp 1, following Fig. 1. In the above description, the inner electrode 5 is arranged in multiple regions in the circumferential direction of the inner tube 12. However, as shown in Fig. 14, the inner electrode 5 may be arranged in one region in the circumferential direction of the inner tube 12.

[0060] <3> In the above description, all corners 6 of the inner electrode 5 are located inside the outer peripheral region A1. However, the present invention is not limited to this. For example, in consideration of the fact that the inner electrode 5 is inserted into the inner tube 12 from the end side in the +X direction (see FIG. 3 , etc.), only the corners 6 located on the +X side of the inner electrode 5 may be located inside the outer peripheral region A1.

[0061] <4> The configuration of the excimer lamp 1 according to the present invention is not limited to the configuration shown in the drawings. [Explanation of symbols]

[0062] 1: Excimer lamp 3: Arc tube 5: Inner electrode 6: Corner 7: Outer electrode 11: Outer tube 11a: External wall surface 12: Inner tube 12a: Inner wall 20: Luminous Space 30: Recess 40 : Power supply A1: Outer region

Claims

1. an arc tube including an outer tube extending in a tube axis direction, and an inner tube extending in the tube axis direction and disposed within the outer tube, wherein the outer tube and the inner tube are sealed at their ends in the tube axis direction; a light-emitting gas sealed in a light-emitting space sandwiched between the outer tube and the inner tube; an outer electrode arranged on an outer wall surface of the outer tube and having a net-like or linear shape; an inner electrode disposed on an inner wall surface of the inner tube and extending circumferentially from one end to the other end, an excimer lamp characterized in that, at an end portion in the tube axis direction, a corner portion located at the peripheral end portion in the circumferential direction of the inner electrode is located inside an outer edge region formed by virtually extending both the side of the inner electrode extending in the tube axis direction and the side of the inner electrode extending in the circumferential direction.

2. 2. The excimer lamp according to claim 1, wherein the inner electrode is arranged in a plurality of regions in the circumferential direction.

3. 3. The excimer lamp according to claim 1, wherein the corners of the inner electrode are linearly chamfered.

4. 3. The excimer lamp according to claim 1, wherein the corners of the inner electrode are chamfered in an arc shape.

5. 3. The excimer lamp according to claim 1, wherein the corners of the inner electrode are shaped to be spaced apart from the inner wall surface of the inner tube.

6. 3. The excimer lamp according to claim 1, wherein the inner electrode is made of aluminum.

Images