JP2006012681A - Excimer lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excimer lamp composed by preventing undesired creeping discharge between an internal electrode exposed from an open part at least at one end of an inner tube formed so as to cover the internal electrode in a discharge vessel and an external electrode, in an excimer lamp with the internal electrode formed in the discharge vessel provided with the external electrode on the outside surface. <P>SOLUTION: This excimer lamp is characterized by forming, at an end of the inner tube formed so as to cover the internal electrode in the discharge vessel, a creeping discharge prevention means for preventing creeping discharge between the internal electrode projecting from the inner tube and the external electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an excimer lamp that discharges through a dielectric material and emits excimer light, and particularly relates to an excimer lamp having an internal electrode in a discharge space.

  As a technique related to the present invention, for example, there is JP-A-2-7353, in which a discharge gas for forming excimer molecules is filled in a discharge vessel and discharged through a dielectric. An excimer lamp is disclosed in which excimer molecules are generated in an internal discharge gas and ultraviolet light emitted from the excimer molecules is extracted.

  This excimer lamp is also known to have characteristics such as strong emission of ultraviolet light having a single wavelength, which is not found in conventional low-pressure mercury discharge lamps or high-pressure discharge lamps. In addition to the above publications, light emitting devices using excimer lamps are disclosed in, for example, Japanese Patent No. 2854255, Japanese Patent Application Laid-Open No. 2002-168999, and the like.

  The excimer lamp (dielectric barrier discharge lamp) disclosed in Japanese Patent No. 2854255 and Japanese Patent Application Laid-Open No. 2002-168999 is a double-cylindrical type in which a cylindrical outer tube is also coaxially disposed outside a cylindrical inner tube. The outer electrode is arranged on the outer surface of the outer tube, the inner electrode is arranged inside the inner tube, and the space formed between the outer tube and the inner tube is used as the discharge space. .

FIG. 7 shows a schematic configuration of the conventional excimer lamp. (A) shows the whole cross-sectional view, (b) shows the AA cross-sectional view of (a).
The excimer lamp 60 has a cylindrical shape as a whole and is made of synthetic quartz glass. In the discharge lamp 60, the outer tube 61 and the inner tube 62 are arranged coaxially to form a double cylindrical tube, and both ends are closed, so that a discharge space S is formed between the outer tube 61 and the inner tube 62. Excimer molecules are formed in the discharge space S by dielectric barrier discharge, and a discharge gas, for example, xenon gas, that emits vacuum ultraviolet light from the excimer molecules is enclosed.
A net-like outer electrode 63 that is one electrode is provided on the outer surface of the outer tube 61, and an inner electrode 64 that is the other electrode is provided inside the inner tube 62.
An AC power supply (not shown) is connected between the outer electrode 63 and the inner electrode 64, thereby forming excimer molecules in the discharge space and emitting ultraviolet light. The discharge gas is selected according to the emission wavelength. For example, when xenon gas is used, light having a wavelength of 172 nm is emitted.

  By the way, in the excimer lamp having this structure, (1) the two quartz glass tubes, the inner tube and the outer tube, are formed in a double cylindrical shape, so that the whole discharge vessel becomes large, and the inner tube is supported by welding at the end. (2) A manufacturing process for joining two quartz glass tubes at both ends is necessary, and this manufacturing process is complicated and cumbersome. (3) Inner tube The temperature is higher than that of the outer tube that can be cooled, and a large load is applied due to thermal expansion.In particular, stress concentrates on the joint with the outer tube and is easily damaged, and the effect becomes more serious as the lamp becomes longer. There is a problem that there is.

In addition, there is an excimer lamp having a structure in which an internal electrode extends into a discharge space, as shown in, for example, Japanese Patent No. 3506055 instead of a double cylindrical type. In this structure, since the discharge vessel is composed of one cylindrical body and there is no equivalent to the inner tube in the double cylindrical type, some of the above problems can be solved.
However, in the excimer lamp having such a structure, since the internal electrode is exposed in the discharge space and the electrode directly acts on the discharge space, (1) the spatial distribution of the discharge generated from the electrode tends to be uneven. (2) If attention is not paid to the polarity of the power supplied to the electrode, an arc-shaped discharge is generated and excimer light is not generated efficiently. (3) When an arc-shaped discharge is formed, the portion becomes red hot and There are other problems such as burnout, (4) the inner electrode metal spatters and contaminates the light extraction portion of the discharge vessel.
Japanese Patent Laid-Open No. 2-7353 Japanese Patent No. 2854255 JP 2002-168999 A Japanese Patent No. 3506055

    The problem to be solved by the present invention is to eliminate the complexity of the structure of the double cylindrical excimer lamp, and to eliminate the discharge defects of the excimer lamp having the structure in which the internal electrode is directly exposed in the discharge space. An object of the present invention is to provide an excimer lamp having a novel structure in which an internal electrode in a space is covered with a dielectric having an open end.

The present invention includes a discharge vessel filled with a discharge gas, an internal electrode extending in the longitudinal direction inside the discharge vessel and hermetically sealed at an end of the discharge vessel, and an outer surface of the discharge vessel. In the excimer lamp comprising the outer electrode, the outer surface of the inner electrode is covered with an inner tube made of a dielectric material having at least one end opened in the discharge space. And the inner tube extends longitudinally beyond the end of the corresponding outer electrode, where the end has an undesirable creepage between the inner electrode and the outer electrode protruding from the inner tube. It has a creeping discharge preventing means for preventing discharge.

Further, the creeping discharge preventing means is creeping distance extending means.
Furthermore, the creeping discharge preventing means is charge reducing means for reducing charges accumulated on the outer surface near the end of the inner tube.

In the excimer lamp of the present invention, since the inner tube made of a dielectric material is provided on the outer periphery of the inner electrode, two dielectrics are interposed between the inner electrode and the outer electrode. A discharge is easily formed in the space. In addition, since arc-like discharge is not generated regardless of the power supply polarity, the excimer light generation efficiency is high and the problem that the electrode burns out does not occur.
In addition, since the creeping discharge preventing means is provided at the end of the inner tube, undesired creeping discharge between the inner electrode protruding from the inner tube and the outer electrode is prevented, and the inner electrode in the inner tube is prevented. And a stable discharge between the outer electrode and the outer electrode.

  Examples of the excimer lamp of the present invention will be described below with reference to FIGS.

FIG. 1A is a side sectional view obtained by cutting the excimer lamp of the present invention in the longitudinal direction. 1B is a cross-sectional view of FIG. 1A, and FIG. 2 is an enlarged view of a main part A thereof.
The excimer lamp 1 has a discharge vessel 2 made of a dielectric material, for example, synthetic quartz glass. The discharge vessel 2 is hermetically sealed to form a tubular light-emitting portion 21 and light-emitting portions 21 at both ends thereof in an airtight manner. A light emitting space S is formed in the light emitting part 21 and filled with a discharge gas.
Inside the discharge vessel 2, a coiled internal electrode 3 is arranged along the tube axis X of the discharge vessel 2, and an outer electrode 4 is arranged on the outer surface of the discharge vessel 2. The internal leads 6 at both ends of the internal electrode 3 are respectively connected to one end of a metal foil 7 embedded in a pinched seal part 22, and the other end of the metal foil 7 is connected to the external part from the seal part 22. An external lead 8 is connected so as to extend in the direction toward the end.

An inner tube 5 made of a dielectric material is provided on the outer periphery of the internal electrode 3 so as to cover it. The inner tube 5 is open at both ends in the discharge space S, and is covered with at least a portion that discharges between the inner electrode 3 and the outer electrode 4, and exceeds the outer electrode 4 in the axial direction. It is extended.
The inner tube 5 may be supported by the light emitting unit 21 by a support body (not shown), or may be supported by the internal electrode 3 by a support body (not shown).
The discharge space S formed inside the light emitting unit 21 is filled with, for example, xenon gas as a discharge gas for forming excimer molecules by discharge with a dielectric material interposed therebetween.

In addition, although the internal electrode 3 showed the coil-shaped thing, it is not restricted to this, A rod-shaped and rod-shaped thing may be sufficient. However, when a coiled electrode is adopted as the internal electrode 3, it has a buffer function against the expansion in the axial direction, absorbs the thermal expansion difference from the discharge vessel 2 made of quartz glass, and cracks in the sealing portion 22 occur. There is an advantage that generation can be prevented.
Further, the outer electrode 4 is also exemplified in a semi-cylindrical shape in the illustrated example, but is not limited thereto, and may be a cylindrical translucent electrode such as a mesh electrode. It is.
Further, the structure of the sealing portion 22 is not limited to the pinch seal, but may be another foil seal, that is, a shrink seal structure, or a so-called joint seal. The advantage of the joint seal is that the bondability between the glass and the electrode is improved, and the occurrence of gas leakage and cracks in the sealed portion can be more reliably prevented.

As shown in detail in FIG. 2, in the vicinity of the end portion of the inner tube 5, an enlarged diameter portion 51 whose diameter gradually increases is formed on the trumpet. The enlarged diameter portion 51 functions as a creeping discharge preventing means, and is for increasing the creeping distance from the end of the outer electrode 4 to the internal electrode 3. Therefore, the enlarged diameter portion 51 extends beyond the outer electrode 4 and is provided on the sealing portion 22 side. However, the position and size of the enlarged portion 51 are provided on the outer electrode 4 and the inner tube 5 of the inner electrode 3. It is selected so that undesired creeping discharge does not occur between the part 31 and the uncovered part.
In the example shown in the figure, the creeping distance L is a distance L1 from a position A corresponding to the end E of the outer electrode 4 to a position B corresponding to E of the inner tube 5 on the inner peripheral surface of the light emitting unit 21, The total of the distance L2 along the outer surface of the enlarged diameter part 51 from the end part C of the enlarged diameter part 51 to the position D of the shortest distance from C to the internal electrode 3 (L = L1 + L2 + L3). Therefore, the creepage distance can be increased by adding the distance L3 from C to D as compared with the structure having the same overall length and no enlarged diameter portion.
The enlarged diameter portion 51 is not limited to the illustrated trumpet shape, and may be a tapered or stepwise enlarged diameter portion. In short, it has a structure in which a distance is added as compared with a straight tubular shape. Any other structure may be used.

  A high-frequency power supply (not shown) is connected to the internal electrode 3 and the external electrode 4, and a dielectric barrier discharge is generated between the electrodes via the discharge vessel 2 and the inner tube 5 which are dielectric materials, and excimer emission occurs. .

  In the excimer lamp of the present invention, it is not preferable that the inner tube 5 extends to the sealing portion 22 and is embedded in the sealing portion 22. This is because if the inner tube 5 is embedded in the sealing portion 22, the same problem as the excimer lamp having the double cylindrical structure described in the background art arises.

As described above, according to the excimer lamp having the structure shown in FIGS. 1 and 2, the greatest feature is that the diameter-enlarged portion is formed at the end of the inner tube, and the advantages thereof will be described below.
The excimer lamp of the present invention has a structure in which the inner tube is not embedded in the sealing portion for the reasons described above, and the end portion of the inner electrode is directly exposed to the discharge gas without being covered by the inner tube. It is. For this reason, unless a sufficient distance (referred to as creepage distance) is secured between the end portion of the outer electrode and the portion not covered by the inner tube of the inner electrode, an undesirable creeping discharge occurs between them. This causes a problem that the stability of discharge between the inner and outer electrodes is lost. More specifically, such creeping discharge is considered to occur from a location corresponding to the end of the outer electrode of the inner tube toward the inner electrode protruding from the inner tube.
To make the creepage distance sufficient to prevent this, simply trying to increase the length of the inner tube relative to the outer electrode, effective discharge formation between the inner and outer electrodes covered by the inner tube The total length of the discharge vessel becomes longer than the length of the portion, in other words, the proportion of the discharge forming portion with respect to the total length of the lamp decreases, which is not preferable.
On the other hand, according to the structure of the excimer lamp of the present invention in which the enlarged diameter portion 51 is formed at the end of the inner tube 5, the creepage distance is increased due to the presence of the enlarged diameter portion 51. A sufficient creeping distance can be ensured without shortening, and the occurrence of undesired creeping discharge can be reliably prevented.

Numerical examples of the excimer lamp 1 shown in FIG.
The discharge vessel 2 has a total length (including the sealing portion 22) of 220 mm to 2820 mm, for example, 1620 mm, a total length of the light emitting unit 21 of 100 mm to 2700 mm, for example, 1500 mm, and an outer diameter of 10 mm to 50 mm, for example, 16 mm, and the inner diameter is 8 mm to 48 mm, for example, 14 mm.
The internal electrode 3 has a total length of 190 mm to 2790 mm, for example, 1590 mm, an outer diameter of 1 mm to 40 mm, for example 3 mm, and a pitch of 0.5 mm to 10 mm, for example 2 mm.
The inner tube 5 has a total length of 170 mm to 2770 mm, for example, 1570 mm, an outer diameter of 2 mm to 42 mm, for example 4 mm, and an inner diameter of 1 mm to 40 mm, for example 3 mm. The maximum outer diameter of the enlarged diameter portion 51 is 4 mm to 46 mm, for example, 12 mm. In addition, the overall length of the outer electrode 4 is 100 mm to 2700 mm, for example 1500 mm.
The creepage distance L is 3 mm to 150 mm, for example, 80 mm.

  FIG. 3 shows another creeping distance extending means. In the drawing, a partition plate 10 made of a non-conductive material is provided in the vicinity of the end of the inner tube 5 positioned outward from the end of the outer electrode 4. It is a thing. The partition plate 10 may be formed by welding another member made of a nonconductive material such as quartz glass or ceramics to the inner tube 5 or by expanding the inner tube 5 itself.

  According to the excimer lamp 1 shown in FIG. 3, a distance corresponding to the height H of each partition member 10 is added to the creeping distance L corresponding to the number of partition members 10. Accordingly, the creeping distance L is extended without reducing the proportion of the discharge forming portion with respect to the total length of the lamp, and therefore, the occurrence of creeping discharge from the outer electrode 4 to the inner electrode 3 that is not covered by the inner tube 5 can be well prevented. .

With respect to the second embodiment shown in FIG. 3, numerical examples of portions different from the first embodiment shown in FIGS. The partition member 10 has an outer diameter of 7 mm to 47 mm, for example, 13 mm. The inner diameter is 2 mm to 42 mm, for example 4 mm. The thickness (in the tube axis X direction) is 1 mm to 10 mm, for example, 3 mm. The creepage distance L is 3 mm to 150 mm in the case where two partition members 10 are provided, and is 80 mm, for example.

The embodiment shown in FIGS. 4 to 6 is a case where charge reducing means for reducing the amount of charge generated on the outer surface of the end portion of the inner tube 5 is adopted as creeping discharge preventing means.
In Example 3 in FIG. 4, the dielectric 11 is additionally attached to the outer surface of the end portion of the inner tube 5 by welding or the like. The additional dielectric 11 is preferably made of the same material as that of the inner tube 5. When the inner tube 5 is made of quartz glass, the additional dielectric 11 is also made of quartz glass. In this case, it can also be said that the inner tube 5 is thicker in the vicinity of the end portion than the other portions.

  By doing so, the charge accumulated on the outer surface of the end thick portion 11 of the inner tube 5 is less than the charge in other parts of the inner tube 5, and therefore, from the end of the outer electrode 4. The discharge to the internal electrode 3 outside the inner tube 5 is difficult to be transmitted, and creeping discharge can be prevented.

In FIG. 5, the basic concept of the fourth embodiment is the same as that of the third embodiment. In this embodiment, the internal lead 6 connected to the internal electrode 3 extends to the inside of the inner tube 5. This is the case. In this embodiment, the additional dielectric 12 provided at the end of the inner tube 5 is provided on the inner surface of the inner tube 5.
The effect on creeping discharge prevention in the fourth embodiment is the same as that in the third embodiment, except that the outer surface of the inner tube 5 is smoothed.

FIG. 6 shows a fifth embodiment, where FIG. 6 (a) is a side sectional view and FIG. 6 (b) is a transverse sectional view.
In FIG. 6, a conductive member 13 such as a metal ring or metal wire is wound around the end of the inner tube 5, and the other end 13 a extends toward the inner wall of the discharge vessel 2. Further, it may be in contact with the discharge vessel 2.
In this embodiment, the electric charge accumulated on the outer surface of the end portion of the inner tube 5 escapes from the other end portion 13a to the discharge vessel 2 side via the conductive member 13, and as a result, is accumulated on the outer surface of the end portion. The charge decreases. Therefore, creeping discharge from the end of the outer electrode 4 to the inner electrode 3 outside the inner tube 5 is prevented.

Example 1 of this invention is shown. The elements on larger scale of FIG. Example 2 is shown. Example 3 is shown. Example 4 is shown. Example 5 is shown. A conventional example is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Excimer lamp 2 Discharge vessel 21 Light emission part 22 Sealing part 3 Internal electrode 4 Outer electrode 5 Inner tube 51 Expanded part 6 Internal lead 7 Metal foil 8 External lead 10 Partition plates 11 and 12 Additional dielectric (end thick part) )
13 Conductive members

Claims (8)

A discharge vessel filled with a discharge gas, an internal electrode extending in the longitudinal direction inside the discharge vessel and hermetically sealed at the end of the discharge vessel, and an outer electrode disposed on the outer surface of the discharge vessel In an excimer lamp consisting of
The inner electrode is covered with an inner tube made of a dielectric material at least one end of which discharges between the inner electrode and the outer electrode, and at least one end thereof is opened in the discharge space.
The inner tube extends beyond the end of the corresponding outer electrode in the longitudinal direction, and the end prevents an undesirable creeping discharge between the inner electrode and the outer electrode protruding from the inner tube. An excimer lamp having creeping discharge preventing means. The excimer lamp according to claim 1, wherein the creeping discharge preventing means is a creeping distance extending means. The excimer lamp according to claim 2, wherein the creeping distance extending means is a diameter-expanded portion formed at an end portion of the inner tube. The excimer lamp according to claim 2, wherein the creeping distance extending means is a non-conductive partition plate provided on an outer periphery in the vicinity of an end portion of the inner tube. 2. The excimer lamp according to claim 1, wherein the creeping discharge preventing means is charge reducing means for reducing charges accumulated on an outer surface in the vicinity of an end portion of the inner tube. 6. The excimer lamp according to claim 5, wherein the charge reducing means is an end thick portion formed thicker in the vicinity of the end portion of the inner tube than others. 6. The excimer lamp according to claim 5, wherein the charge reducing means is a conductive member attached to an outer surface near the end of the inner tube and having the other end directed toward the inner wall of the discharge vessel. The excimer lamp according to any one of claims 1 to 7, wherein an end portion of the discharge vessel is formed by a foil seal.

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