JPH0997597A - Dielectric barrier discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life dielectric barrier discharge lamp which can be prevented from being unlighted by the cracking at the connecting part between an inside tube and an outside tube. SOLUTION: This lamp has a double tube structure in which an outside tube 3 and an inside tube 2 are concentrically arranged, one electrode 6 is provided on the outer surface of the outside tube 3, the other electrode is provided on the inner surface of the inside tube 2, and an excimer molecule is formed by dielectric barrier discharge in a discharge space 4 between the outside tube 3 and the inside tube 2. This lamp has a direct emission preventing means for the vacuum ultraviolet ray generated in the discharge space 4 to the connecting parts 11, 12 between the inside tube 2 and the outside tube 3. This direct emission preventing means can be attained, for example, by a metal thin film such as oxide titanium film or barium, or the pleats of the outside tube 3 and the inside tube 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called dielectric barrier discharge lamp which forms excimer molecules by dielectric barrier discharge and utilizes light emitted from the excimer molecules, and for example, ultraviolet rays of photochemical reaction. It is used as a light source.

[0002]

2. Description of the Related Art A technique related to the present invention is described in, for example, Japanese Unexamined Patent Publication No. 1-144560 or US Pat. No. 9,837,484, in which a gas for producing excimer molecules in a discharge vessel. A dielectric barrier discharge lamp is described, which fills the core and extracts the light emitted from the excimer molecules by a dielectric barrier discharge. Another name for this dielectric barrier discharge lamp is ozonizer discharge or silent discharge. The revised edition of the "Discharge Handbook" published by the Institute of Electrical Engineers of Japan, June 2001, 7th edition, 2nd edition
Explained on page 63.

In this document, at least a part of a substantially cylindrical discharge vessel also serves as a dielectric for a dielectric barrier discharge,
It also states that the dielectric is transparent and emits light from the excimer molecules. Further, the outer tube and the inner tube are coaxially arranged as a double tube structure, a mesh electrode is provided as one electrode on the outer surface of the outer tube, and the other electrode is provided by vapor deposition on the inner surface of the inner tube. It is also described to perform a dielectric barrier discharge in the discharge space between the outer tube and the inner tube.

This dielectric barrier discharge lamp has features which are not found in conventional low-pressure mercury lamps and high-pressure arc discharge lamps, for example, its central wavelength is 172 nm, 222 nm, 308 n.
It has a property that it radiates ultraviolet rays having a short wavelength of m and selectively generates light with a single wavelength close to the line spectrum with high efficiency. As described above, if the outer shape is substantially cylindrical and the outer tube and the inner tube are coaxially arranged, commercially available quartz glass can be used for the discharge vessel, and the structure of the entire lamp is also reduced. It also has the feature of being simple and easy to manufacture.

However, while the lamp is on, the discharge gas sealed inside may leak from the container constituting the lamp, and if the lamp continues to be turned on with such a leak, it will eventually occur. It will cause the lamp to go out. That is, the occurrence of such a leak means that the life of the lamp is shortened.

[0006]

The problem to be solved by the invention is to provide a long-life dielectric barrier discharge lamp.

[0007]

A dielectric barrier discharge lamp according to the present invention has a double tube structure in which an outer tube and an inner tube are coaxially arranged, and one electrode is provided on the outer surface of the outer tube. The other electrode is provided on the inner surface of the inner tube, and the discharge space formed between the outer tube and the inner tube is filled with a discharge gas that forms excimer molecules by dielectric barrier discharge. The present invention is characterized in that it has means for preventing direct irradiation of ultraviolet light generated in the discharge space with respect to the joint portion between the outer tube and the inner tube.

Further, as the means for preventing direct radiation, the joint portion is made of a thin film selected from titanium oxide, cerium oxide and zinc oxide.

Further, the direct-ray preventing means is characterized in that the joint portion is made of a metal thin film.

Further, it is characterized in that the means for preventing direct radiation is constituted by an outer tube provided between the joint portion and the discharge space and a fold of the outer tube.

Further, the direct-ray preventing means is constituted by a glass fiber cotton provided between the joint portion and the discharge space.

Further, the exhaust pipe remaining portion is provided at the joint portion, and in particular, the direct radiation preventing means is provided at this portion.

Further, as the means for preventing direct radiation, a metal film is provided on the inner surface of the remaining portion of the exhaust pipe.

[0014]

The fact that the discharge gas leaks from the discharge vessel is because a crack is generated in the discharge vessel for some reason. The present inventors have investigated the occurrence of this crack in detail and found that the mechanism of occurrence is all right. That is, the inner tube and the outer tube that make up the discharge vessel are
In the manufacture of a lamp, they are joined together by melting or the like to make the inside airtight, but at this time, the joining portion has a slight processing strain during the joining process, although it is minute. Further, the ultraviolet light generated by the dielectric barrier discharge is not absorbed by the discharge gas sealed in the container, and the joint portion is irradiated with high-intensity ultraviolet light, particularly vacuum ultraviolet light. As a result, it can be said that the growth of processing strain at the time of the bonding processing is promoted, and as a result, cracks occur.

The rate of occurrence of cracks is such that the greater the discharge power density per unit volume of the discharge space, and
The longer the discharge space, the larger. Particularly, when the discharge power density per unit volume of the discharge space is P (W / cm ³ ) and the length of the discharge space is L (cm), “P × L” is 10 (W / cm ² ). In the above, the rate of occurrence of cracks increased significantly. It is speculated that the main reason for this is that the intensity of the ultraviolet light that directly irradiates the joint between the inner tube and the outer tube becomes stronger as the discharge power density per unit volume of the discharge space increases and as the discharge space becomes longer. To be done.

Further, in the present invention, since the direct irradiation preventing means is provided for the joint portion of the inner tube and the outer tube, the occurrence of the cracks is reduced, and a long-life dielectric barrier discharge lamp can be obtained.

[0017]

1 shows the structure of a dielectric barrier discharge lamp according to the present invention. The discharge vessel 1 has a double tube structure in which an inner tube 2 and an outer tube 3 made of synthetic quartz glass are coaxially arranged, and joint parts 11 and 1 are provided at both ends of the inner tube 2 and the outer tube 3.
2 and the inside is hermetically sealed to form a discharge space 4 therebetween. Further, a part of the joint portion 12 is provided with the remaining portion 9 of the exhaust pipe for evacuating the internal gas during manufacturing and further introducing the discharge gas. To give an example of the size of this dielectric barrier discharge lamp,
The discharge vessel 1 has a total length of about 750 mm, the inner tube 2 has an outer diameter of about 14 mm, a wall thickness of 1 mm, and the outer tube 3 has an inner diameter of about 24 mm.
It has a wall thickness of 1 mm. The length of the discharge space is 700
mm.

Here, titanium oxide films 13 and 14 are provided on the inner surfaces of the joints 11 and 12, respectively. This titanium oxide film 1
3 and 14 are obtained by manufacturing the discharge vessel 1 by glass processing, and then joining an organic titanium compound dissolved in an organic solvent to the joining portion 1
Apply to inner surface of 1, 12 and then 85 in air
It is provided by firing at about 0 ° C. As still another manufacturing method, before manufacturing the discharge vessel 1, a titanium oxide film is formed on the appropriate portions of the outer tube 3 and the inner tube 2 by the same means as described above, and then the glass is formed. The discharge vessel 1 can also be manufactured by processing. In this method, a part of titanium oxide is melted in the quartz glass.

On the outer surface of the inner tube 2, there is provided an inner electrode 5 made of an aluminum thin film which also serves as a reflection plate for light emitted from excimer molecules and an electrode for dielectric barrier discharge. The outer tube 3 is a dielectric for a dielectric barrier discharge, is transparent to vacuum ultraviolet excimer light, and has an electrode 6 made of a conductive net that transmits light on the outer surface thereof. That is, the outer tube 3 also serves as a light extraction window.

The discharge space 4 is filled with a discharge gas mainly containing xenon or a discharge gas mainly containing argon and chlorine. Specifically, for example, 33 kPa
The discharge space 4 is filled with xenon. When dielectric barrier discharge is performed by the high frequency power supply 10 in such a dielectric barrier discharge lamp, vacuum ultraviolet light having a center of 172 nm, which is excimer light of xenon, and argon-light are emitted.
Vacuum ultraviolet light having a 175 nm center, which is the excimer light of chlorine, is emitted with high efficiency. Specifically, when the dielectric barrier discharge lamp was turned on by the power supply 10 at 120 W, vacuum ultraviolet light having a center of 172 nm, which is excimer light of xenon, and a full width at half maximum of 14 nm was emitted with high efficiency.

It is desirable that such emitted light is completely emitted from the desired light extraction portion.
In the joint portions 11 and 12 of the inner pipe 2 and the outer pipe 3, it is preferable to prevent direct irradiation in order to suppress the generation of cracks. Specifically, titanium oxide films 13 and 14 are applied to the joint portions 11 and 12. Therefore, the joint part 1
No cracks were generated in Nos. 1 and 12, and the life was about twice as long as that of the conventional dielectric barrier discharge lamp having no titanium oxide film. As the means for preventing direct radiation, instead of the titanium oxide film, cerium oxide, zinc oxide, or a thin film made of a substance in which at least one of them is mixed may be used.

FIG. 2 shows another embodiment. In this embodiment, a titanium oxide film or the like is not applied to the joint portion as a direct radiation preventing means, but the outer tube 3 is provided with folds 31 and 32 and the inner tube 2 is provided between the discharge space 4 and the joint portions 11 and 12. The folds 33, 34 are provided on the folds, and the folds allow the joint portion 11,
This is what prevents direct exposure of vacuum ultraviolet light to 12. According to such a configuration, there is an advantage that a means for preventing direct irradiation of vacuum ultraviolet light can be realized only by processing the outer tube 3 and the inner tube 2. It is also possible to bond a disc-shaped member such as ceramics to the inner tube or the outer tube to form the folds.

FIG. 3 shows another embodiment. In this embodiment, a titanium oxide film or the like is not applied as a means for preventing direct radiation, but a metal thin film is provided only on the pipe end where the exhaust pipe residual portion 9 exists. A vapor deposition film of barium is applied to this metal thin film. Further, a fold 43 is provided to prevent the barium vapor deposition source 41 from moving to the discharge space 4. In such a method for manufacturing a metal thin film, first, the discharge vessel 1 is filled with xenon gas, for example, at about 40 kPa, and then the exhaust pipe is sealed. Then, the barium vapor deposition source 41 is heated at a high frequency to form a barium vapor deposition film 42.

Usually, in the work of forming a barium getter film inside the lamp, first, the barium vapor deposition source is heated while vacuum evacuation is performed to form a barium vapor deposition film, and then a discharge gas is filled and an exhaust pipe is installed. Seal. For this reason,
At the inner surface of the remaining part of the exhaust pipe and in the vicinity of the joint,
Barium was scattered and the glass was exposed. Since the manufacturing method as described above is used in the present invention, the barium vapor-deposited film 42 is the most likely to cause cracks in the exhaust pipe residual portion 9
Since it is also formed on the inner surface of the, a long-life dielectric barrier discharge lamp can be obtained. It is needless to say that applying a metal thin film such as a barium vapor deposition film is not limited to providing it on the inner surface of the exhaust pipe remaining portion 9 and can be applied to other joining portions.

Further, as a means for preventing direct radiation, cotton made of glass fiber may be provided between the joint and the discharge space. This glass fiber cotton is specifically quartz glass cotton made of fused quartz glass fiber. In this case, since the vacuum ultraviolet light is absorbed by the glass fiber cotton, the direct irradiation of the vacuum ultraviolet rays to the joint portion is completely prevented. It is blocked, and as a result, the occurrence of cracks can be suppressed well.

[Brief description of 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.

FIG. 3 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 Discharge space 5 Inner electrode 6 Outer electrode 9 Exhaust tube remainder 11,12 Joint part 13,14 Titanium oxide film 31, 32, 33, 34

Front page continued (72) Inventor Nozomi Hishinuma, 1194 Sado, Bessho-cho, Himeji-shi, Hyogo Ushio Denki Co., Ltd.

Claims (7)

[Claims] 1. A double tube structure in which an outer tube and an inner tube are coaxially arranged, one electrode is provided on an outer surface of the outer tube, and the other electrode is provided on an inner surface of the inner tube. And a discharge gas formed between the outer tube and the inner tube is filled with a discharge gas that forms excimer molecules by a dielectric barrier discharge. A dielectric barrier discharge lamp having means for preventing direct irradiation of ultraviolet light generated in the discharge space with respect to a joint portion of a tube. 2. The dielectric barrier discharge lamp according to claim 1, wherein the direct radiation preventing means is a thin film selected from titanium oxide, cerium oxide and zinc oxide. 3. The dielectric barrier discharge lamp according to claim 1, wherein the direct exposure preventing means is a metal thin film. 4. The dielectric barrier discharge according to claim 1, wherein the direct radiation preventing means is the outer tube and a fold of the outer tube provided between the joining portion and the discharge space. lamp. 5. The dielectric barrier discharge lamp according to claim 1, wherein the direct-irradiation preventing means is a glass fiber cotton provided between the joining portion and the discharge space. 6. The dielectric barrier discharge lamp according to claim 1, wherein an exhaust pipe remaining portion is provided at the joint portion. 7. The dielectric barrier discharge lamp according to claim 6, wherein a metal coating is provided on the inner surface of the remaining portion of the exhaust pipe.