JP3269213B2 - Dielectric barrier discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example,
The present invention relates to an improvement in an ultraviolet light source used for surface cleaning, sterilization, and the like, and more particularly to an improvement in a so-called dielectric barrier discharge lamp that forms excimer molecules by dielectric barrier discharge and uses light emitted from the excimer molecules.

[0002]

2. Description of the Related Art As a technique related to the present invention, there is, for example, Japanese Patent Laid-Open Publication No. 2-7353, in which a discharge vessel is filled with a discharge gas for forming excimer molecules, and a dielectric material is filled. Excimer molecules are formed by barrier discharge (also known as ozonizer discharge or silent discharge; see the revised Electric Discharge Handbook, published by the Institute of Electrical Engineers of Japan, reprinted on June 7, 2001, page 263), and light emitted from the excimer molecules is extracted. A radiator, a dielectric barrier discharge lamp, is described. Japanese Patent Laid-Open Publication No. 2-7353 discloses a radiator in which a discharge vessel of a dielectric barrier discharge lamp is provided with luminescence (for example, phosphor) for converting ultraviolet light into light of another wavelength. . That is, a discharge space is formed by providing two light-transmitting dielectrics such as quartz glass plates facing each other, and filling the discharge space with a rare gas, deuterium or a mixed gas of a rare gas and a halogen, A configuration / method is known in which an electrode is provided on a surface of the two dielectrics not facing the discharge space, and an AC voltage is applied to the electrode to generate a silent discharge in the discharge space and emit ultraviolet rays. ing. As the dielectric, sapphire, magnesium fluoride, calcium fluoride and the like are known in addition to quartz glass. The dielectric barrier discharge lamp as described above has a conventional low-pressure mercury discharge lamp, such as having a large degree of freedom in the shape of the discharge vessel and being able to use a corrosive gas such as halogen because the conductive electrode is not exposed in the discharge space. It is useful because it has various features not found in lamps and high-pressure arc discharge lamps. However, the dielectric barrier discharge lamp as described above has a problem that the life characteristics are not always sufficient.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-performance dielectric barrier having a sufficient life characteristic while maintaining the advantage of a dielectric barrier discharge lamp in that the shape of the discharge vessel is large. It is to provide a discharge lamp.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide at least a discharge vessel filled with a discharge gas for forming excimer molecules by dielectric barrier discharge, and having a window member for extracting light radiated from the excimer molecules. At least a part of the discharge vessel is a dielectric of the dielectric barrier discharge, and a surface of the portion of the dielectric serving as the discharge vessel and the dielectric barrier discharge opposite to the discharge space. This is achieved by providing a member for chemically and mechanically protecting the conductive thin film in the dielectric barrier discharge lamp including the electrode made of the conductive thin film provided in the above. Further, the member for protecting the conductive thin film is made of at least one selected from silicon rubber, fluororesin, oxide, nitride and fluoride, or the conductive thin film is made of aluminum. By configuring, and by constituting a member for protecting the conductive thin film with a conductive substance,
The object of the present invention is further achieved. Further, a member for protecting the conductive thin film, platinum, palladium,
The object of the present invention can be achieved even more by comprising at least one selected from gold, silver and nickel. When the discharge vessel has a substantially cylindrical shape, or when the light emitted from the excimer molecule has a wavelength of 200 n.
The above configuration is preferable in the case where ultraviolet rays of m or less are obtained.

[0005]

The discharge vessel is filled with a discharge gas for forming excimer molecules by dielectric barrier discharge, and has a window member for extracting light emitted from the excimer molecules.
At least a part of the discharge vessel is a dielectric of the dielectric barrier discharge, and a part of the discharge vessel and the dielectric of the dielectric barrier discharge opposite to the surface of the dielectric opposite to the discharge space. In a dielectric barrier discharge lamp provided with a dielectric barrier discharge electrode, a discharge is prevented from being generated between the dielectric and the electrode in a portion serving also as a discharge vessel and a dielectric of the dielectric barrier discharge. For this purpose, the electrode and the dielectric portion need to be in close contact with each other. Therefore, a conductive thin film is directly formed on the dielectric portion by vapor deposition or the like, and this is used as the electrode. While improving the life characteristics of the dielectric barrier discharge lamp described above, the present inventors have found that even if the thin film electrode is slightly damaged, the electric field in that portion becomes strong and the discharge is concentrated. It was discovered that the electrode damage accelerated and the lamp life was shortened.
One of the above-mentioned phenomena is that the electrodes are easily damaged because the electrodes are in the form of a thin film, but the essential cause is that the dielectric barrier discharge tends to concentrate on the edge portion of the damaged thin film. This is a unique phenomenon of the body barrier discharge lamp.

When a member for chemically and mechanically protecting the conductive thin film is provided over the conductive thin film, the conductive thin film is prevented from being chemically and mechanically damaged during assembly or operation of the lamp. Thus, a long-life dielectric barrier discharge lamp is obtained.

[0007] If the member for protecting the conductive thin film is made of at least one selected from silicon rubber, fluororesin, oxide, nitride and fluoride, these materials have mechanical strength. Sufficient and chemically stable to active substances such as oxygen or ozone generated by ultraviolet rays from lamps. In addition, since these materials are electrical insulators, atmospheric gases such as air for conductive thin film electrodes Since a discharge in the inside is prevented, a dielectric barrier discharge lamp having a longer life is obtained.

At the end of the member provided beyond the conductive thin film, the member is irradiated with ultraviolet rays from a lamp. Therefore, when an organic material is used as the member, the end portion is easily deteriorated by ultraviolet rays. When the member to be in contact with the conductive thin film is at least one selected from oxides and nitrides, these materials are resistant to ultraviolet rays, so that deterioration during the life is small. However, since these substances have a weak adhesion strength, if a protective member made of an organic substance such as silicon rubber is further provided on these substances, a dielectric barrier discharge lamp having a longer life can be obtained.
In addition, one of the main causes of damage to the conductive thin film is that ultraviolet rays emitted from the lamp directly act on the conductive thin film in the air or the ultraviolet rays generate ozone from oxygen in the air. Ultraviolet rays cause the ozone to act on the conductive thin film. The member made in contact with the conductive thin film is at least one selected from oxides and nitrides, and these substances are added to the conductive thin film and applied to the end of the lamp. By blocking the extra ultraviolet rays, a dielectric barrier discharge lamp having a longer life can be obtained.

Silicone rubbers of alcohol type, oxime type, acetic acid type, etc. are characterized by being easy to handle.
When these silicon rubbers are used in a dielectric barrier discharge lamp, it is said that a small amount of uncured components evaporate during operation of the lamp, are decomposed by ultraviolet rays from the lamp, and deposit silicon oxide powder on the lamp surface. It turned out to be a problem. It takes a long time of at least several days before the uncured components are completely eliminated, that is, for complete curing. When the silicone rubber is an addition type (a silicone rubber that cures when heated, for example, Shin-Etsu Chemical Co., Ltd. product name KE1830),
Since there is no compound such as acetic acid by-produced during curing, and curing can be performed in a short time by heating, it is possible to extremely reduce uncured components, and therefore, silicon oxide powder precipitates on the lamp surface. And a high quality dielectric barrier discharge lamp can be obtained.

When the conductive thin film is made of aluminum, aluminum has a feature that a high-efficiency dielectric barrier discharge lamp can be obtained because aluminum efficiently reflects short-wavelength ultraviolet rays. However, the surface of aluminum is oxidized. The electrode lead wire is difficult to connect because of its ease, and a connection failure occurs between the aluminum electrode and the electrode lead wire during lighting of the lamp, and abnormal discharge occurs in this portion, thereby shortening the life of the lamp. If the member for protecting the conductive thin-film electrode made of aluminum is made of a conductive material, the connection between the electrode and the electrode lead wire can be made highly reliable, and thus a long-life dielectric barrier discharge lamp can be obtained. Further, a conductive member for protecting the conductive thin film, platinum, palladium,
When composed of at least one selected from gold, silver, and nickel, these metals are chemically stable to active substances such as oxygen or ozone generated by ultraviolet rays from a lamp. Since connection with an electrode lead made of copper, stainless steel wire or the like is easy, the connection between the electrode and the electrode lead can be made highly reliable, and a long-life dielectric barrier discharge lamp can be obtained.

The light emitted from the excimer molecule has a wavelength of 2
Dielectric barrier discharge lamps that emit ultraviolet light having a wavelength of 00 nm or less often generate an active substance that damages the electrodes. However, applying the above-described present invention is advantageous because a damage prevention effect is exhibited. In addition, it is difficult to provide a conductive thin-film electrode on the outer and inner surfaces of the hollow cylindrical dielectric, and therefore, the conductive thin film is easily peeled off from the dielectric. When the present invention is applied to a dielectric barrier discharge lamp characterized in that the dielectric barrier discharge lamp is substantially hollow cylindrical, the degree of freedom of the shape of the discharge vessel, which is a characteristic of the dielectric barrier discharge lamp, is large. A long-life dielectric barrier discharge lamp can be obtained while maintaining the advantages.

[0012]

FIG. 1 is a schematic view of a coaxial cylindrical dielectric barrier discharge lamp according to a first embodiment of the present invention. The discharge vessel 1 is made of synthetic quartz glass having a total length of about 150 mm and has an outer diameter of 14 mm.
A hollow cylindrical discharge space 8 is formed by coaxially disposing an inner tube 2 having a diameter of 2 mm and an outer tube 3 having an inner diameter of about 24 mm and a thickness of 1 mm. The outer tube 3 also serves as a dielectric barrier for the dielectric barrier discharge and a light extraction window member, and has an electrode 4 made of a conductive net that transmits light on its outer surface. On the outer surface of the inner tube 4, there is provided an aluminum thin film electrode 5 which also serves as a light reflection plate and a dielectric barrier discharge electrode. Therefore, the discharge gap is 5 mm. A barium getter 7 is provided in a getter storage chamber 6 provided at one end of the discharge vessel 1. In the discharge space 8 of the discharge vessel, 3
50 Torr of xenon gas was charged. The aluminum thin film electrode 5 is made of an additional type silicon rubber 9 and has a thickness of 0.5 mm.
From 1 mm and cured by heating at 120 ° C. for 1 hour. Assuming that the input power per square centimeter of surface area of the dielectric barrier discharge lamp is 0.4 Watt,
Lighted at 0. As a result, the ultraviolet ray having the maximum value at 172 nm is efficiently radiated, the silicon oxide is not generated due to the silicon rubber, and the aluminum thin film electrode 5 is caused by the ozone generated by the ultraviolet ray having the maximum value at 172 nm. A high-performance dielectric barrier discharge lamp having sufficient life characteristics was obtained while maintaining the advantage of the dielectric barrier discharge lamp without being damaged, and thus having a large degree of freedom in the shape of the discharge vessel. . Since aluminum reflects vacuum ultraviolet rays efficiently, 172
The extraction efficiency of ultraviolet light having a maximum value in nm was increased, and particularly high efficiency was achieved.

In a second embodiment of the present invention, a gas for forming excimer molecules is formed in a discharge vessel having a structure in which the getter accommodating chamber 6 and the getter 7 are removed from the coaxial cylindrical dielectric barrier discharge lamp of FIG. , And neon as a buffer gas, and the aluminum thin-film electrode 5 was covered with boron nitride. In this embodiment, ultraviolet light having a maximum value at a wavelength of 308 nm is efficiently emitted, and the aluminum thin-film electrode 5 is not damaged by oxygen in the air. Therefore, the degree of freedom of the shape of the discharge vessel is reduced. While maintaining the advantage of the dielectric barrier discharge lamp of being large, a high performance dielectric barrier discharge lamp having sufficient life characteristics was obtained.

In the third embodiment of the present invention, the aluminum thin film electrode 5 is covered with a nickel thin film instead of the silicon rubber in the embodiment of FIG. The connection between the electrode 5 and the electrode lead 13 can be made highly reliable and 172 nm.
The aluminum thin film electrode 5 is not damaged by ozone generated by ultraviolet rays having a maximum value,
Therefore, a high-performance dielectric barrier discharge lamp having sufficient life characteristics was obtained while maintaining the advantage of the dielectric barrier discharge lamp that the degree of freedom of the shape of the discharge vessel was large.

FIG. 2 is a schematic diagram of a coaxial cylindrical dielectric barrier discharge lamp according to a fourth embodiment of the present invention. Except for the protection member, it is the same as the first embodiment. On the aluminum thin film electrode 5, as a first protective member, boron nitride powder dispersed in an organic solvent was applied to provide a boron nitride film 11. As a second protective member, additional silicone rubber 1
2 was provided on the boron nitride film 11. Boron nitride film 11
The silicon rubber 12 was provided on the end 14 of the lamp in addition to the aluminum thin-film electrode 5. In the configuration of this embodiment, in addition to directly protecting the aluminum thin-film electrode 5, the emission of extra ultraviolet rays from the end portion 14 can be prevented, so that a high-performance dielectric barrier discharge lamp having longer life characteristics can be obtained. .

[0016]

As described above, according to the present invention, while maintaining the advantage of the dielectric barrier discharge lamp in that the degree of freedom of the shape of the discharge vessel is large, a high performance dielectric material having a sufficient life characteristic is maintained. A barrier discharge lamp can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of a dielectric barrier discharge lamp of the present invention.

FIG. 2 is an explanatory view of another embodiment of the dielectric barrier discharge lamp of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge container 2 Inner tube 3 Outer tube 4 Conductive mesh electrode 5 Conductive thin film electrode 7 Getter 9 Silicon rubber 11 Boron nitride film 12 Silicon rubber

──────────────────────────────────────────────────続 き Continuation of the front page Examiner Katsumi Enari (56) References JP-A-2-7353 (JP, A) JP-A-4-129167 (JP, A) JP-A-5-138014 (JP, A) JP-A-50-110902 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 65/04 G21K 5/00

Claims (8)

(57) [Claims] A discharge vessel is filled with a discharge gas for forming excimer molecules by a dielectric barrier discharge, and has a window member for extracting light emitted from the excimer molecules, and at least a part of the discharge vessel has the window member. An electrode made of a conductive thin film provided on the surface of the dielectric barrier discharge which is a dielectric and also serves as a discharge vessel and a dielectric of the dielectric barrier discharge, on the surface opposite to the discharge space of the dielectric. A dielectric barrier discharge lamp, comprising: a member for chemically and mechanically protecting the conductive thin film. 2. A member for protecting the conductive thin film,
2. The dielectric barrier discharge lamp according to claim 1, wherein the dielectric barrier discharge lamp is at least one selected from the group consisting of silicon rubber, fluororesin, oxide, nitride and fluoride. 3. A member for protecting the conductive thin film,
2. The dielectric barrier discharge lamp according to claim 1, wherein the dielectric barrier discharge lamp is at least one selected from oxides and nitrides, and further has a structure in which a protective member made of an organic material is provided on the member. . 4. The conductive thin film is made of aluminum,
2. The dielectric barrier discharge lamp according to claim 1, wherein the member for protecting the conductive thin film is a conductive material. 5. A member for protecting the conductive thin film,
The dielectric barrier discharge lamp according to claim 4, wherein the lamp is at least one selected from platinum, palladium, gold, silver, and nickel. 6. The dielectric barrier discharge lamp according to claim 1, wherein light emitted from the excimer molecule is ultraviolet light having a wavelength of 200 nm or less. 7. The dielectric barrier discharge lamp according to claim 1, wherein the dielectric barrier discharge lamp has a substantially hollow cylindrical shape. 8. The dielectric barrier discharge lamp according to claim 1, wherein the member for protecting the conductive thin film is an additional type silicon rubber.