JP2022175582A - barrier discharge lamp - Google Patents

Abstract

To provide a barrier discharge lamp capable of increasing the amount of ultraviolet light with which the outside of the barrier discharge lamp is irradiated even when a mesh-shaped external electrode is provided.SOLUTION: A barrier discharge lamp according to an embodiment includes a cylindrical outer tube, an inner tube having a cylindrical shape and provided inside the outer tube substantially coaxially with the outer tube via a gas-filled discharge space, an external electrode provided outside the outer tube and having a mesh shape, an internal electrode provided inside the inner tube, and a plate-like reflective electrode provided between the outer surface of the outer tube and the outer electrode.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to barrier discharge lamps.

There are barrier discharge lamps that irradiate ultraviolet rays with a wavelength of 200 nm or less. Barrier discharge lamps are used, for example, for surface treatment such as removal of organic matter adhering to the surface of an object (light cleaning treatment), surface modification, and formation of an oxide film.

Further, the barrier discharge lamp has an inner tube, an outer tube provided coaxially with the inner tube, an inner electrode provided on the inner surface of the inner tube, and an outer electrode provided on the outer surface of the outer tube. Discharge lamps have been proposed. In such a barrier discharge lamp, when an alternating voltage is applied to the inner electrode and the outer electrode, a dielectric barrier discharge occurs in the discharge space between the inner tube and the outer tube. Accordingly, ultraviolet rays having a specific wavelength are irradiated.

Here, the ultraviolet rays generated in the discharge space are irradiated outside through the outer tube and the outer electrode. In this case, the outer tube can be made of a material that transmits ultraviolet rays, such as synthetic quartz glass. However, since the external electrodes are made of a conductive material such as metal, if the external electrodes are plate-shaped, the ultraviolet rays generated in the discharge space cannot be irradiated to the outside.

Therefore, barrier discharge lamps having mesh-like external electrodes have been proposed. If the mesh-shaped external electrodes are used, ultraviolet rays generated in the discharge space can pass through the external electrodes.

However, if the mesh-shaped external electrode is used, the area of the portion formed of the conductive material is reduced, so the discharge area of the lamp is reduced. As a result, it becomes difficult to increase the amount of ultraviolet light generated and, in turn, the amount of ultraviolet light irradiated to the outside of the barrier discharge lamp. Therefore, it has been desired to develop a barrier discharge lamp that can increase the amount of ultraviolet light irradiated to the outside of the barrier discharge lamp even when a mesh-like external electrode is provided.

JP-A-2002-93377

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a barrier discharge lamp capable of increasing the amount of ultraviolet light irradiated to the outside of the barrier discharge lamp even when a mesh-shaped external electrode is provided. .

A barrier discharge lamp according to an embodiment comprises a cylindrical outer tube; and a cylindrical outer tube provided substantially coaxially with the outer tube via a discharge space filled with a gas. an inner tube; a mesh-like external electrode provided outside the outer tube; an internal electrode provided inside the inner tube; a plate-like outer surface of the outer tube; and the external electrode. and a reflective electrode provided between;

According to the embodiments of the present invention, it is possible to provide a barrier discharge lamp capable of increasing the amount of ultraviolet light emitted to the outside of the barrier discharge lamp even when mesh-shaped external electrodes are provided.

1 is a schematic cross-sectional view for illustrating a barrier discharge lamp according to this embodiment; FIG. FIG. 2 is a schematic cross-sectional view of the barrier discharge lamp in FIG. 1 taken along the line AA. 5 is a graph for illustrating the relationship between the center angle of the reflective electrode and the rate of increase of ultraviolet rays irradiated to the outside of the barrier discharge lamp.

Hereinafter, embodiments will be illustrated with reference to the drawings. In addition, in each drawing, the same reference numerals are given to the same constituent elements, and detailed description thereof will be omitted as appropriate.
FIG. 1 is a schematic cross-sectional view for illustrating a barrier discharge lamp 1 according to this embodiment.
FIG. 2 is a schematic cross-sectional view of the barrier discharge lamp 1 in FIG. 1 taken along line AA.
As shown in FIGS. 1 and 2, the barrier discharge lamp 1 has, for example, an inner tube 2, an outer tube 3, an inner electrode 4, an outer electrode 5, a lead 6, a holder 7, and a reflective electrode 8. FIG.

The inner tube 2 has a tubular shape, and has a shape in which the total length (the length in the tube axial direction) is longer than the tube diameter. The inner tube 2 is, for example, a cylindrical tube.
The outer tube 3 has a cylindrical shape, and has a shape in which the total length (the length in the tube axis direction) is longer than the tube diameter. The outer tube 3 is, for example, a cylindrical tube.

One end of the inner tube 2 and one end of the outer tube 3 are sealed. The other end of the inner tube 2 and the other end of the outer tube 3 are sealed. A space between the inner tube 2 and the outer tube 3 becomes a discharge space 9 . For example, the inner tube 2 is provided inside the outer tube 3 substantially coaxially with the outer tube 3 via a discharge space 9 filled with gas.
That is, the barrier discharge lamp 1 has an arc tube with a double-tube structure.

As will be described later, when the barrier discharge lamp 1 is lit, ultraviolet rays are generated in the discharge space 9 . The generated ultraviolet rays are irradiated outside through the outer tube 3 . Therefore, the outer tube 3 is made of a material having a high ultraviolet transmittance. The outer tube 3 is made of synthetic quartz glass, for example. If the outer tube 3 is made of synthetic quartz glass, it becomes easy to transmit ultraviolet rays having a peak wavelength of 200 nm or less.

Considering that the end of the outer tube 3 and the end of the inner tube 2 are sealed, the material of the inner tube 2 is preferably the same as the material of the outer tube 3 . Therefore, the inner tube 2 is made of synthetic quartz glass, for example.

In the barrier discharge lamp 1 , barrier discharge is performed between the internal electrode 4 and the external electrode 5 to give high-energy electrons to the gas enclosed in the discharge space 9 to generate excimer excited molecules. When the excimer excited molecules return, light having a specific peak wavelength is generated depending on the type of gas. Therefore, the gas enclosed in the discharge space 9 can be appropriately changed according to the application of the barrier discharge lamp 1 . The gas enclosed in the discharge space 9 can be, for example, a rare gas such as krypton, xenon, argon, or neon, or a mixed gas in which a plurality of kinds of rare gases are mixed. The gas may further contain a halogen gas or the like, if necessary.

The gas pressure (filling pressure) in the discharge space 9 at 25° C. can be, for example, about 13 kPa to 150 kPa. The gas pressure (encapsulated pressure) at 25° C. in the discharge space 9 can be obtained from the standard state of the gas (SATP (Standard Ambient Temperature and Pressure): temperature 25° C., 1 bar).

For example, when optically cleaning the surface of a glass plate for a flat panel display, it is preferable to use xenon as the enclosed gas. The sealing pressure of xenon can be, for example, about 50 kPa. If xenon is used as the gas to be sealed, ultraviolet rays having a peak wavelength of 172 nm can be generated, so that the cleaning effect can be enhanced.

The internal electrode 4 is provided inside the inner tube 2 . The internal electrode 4 can be provided on the inner surface of the inner tube 2, for example. In this case, if the gap between the internal electrode 4 and the inner surface of the inner tube 2 becomes large, the amount of power supplied to the discharge space 9 may vary. Therefore, the internal electrode 4 is preferably brought into close contact with the inner surface of the inner tube 2 . For example, the internal electrode 4 may have a slit extending in the axial direction, and the elastic force of the internal electrode 4 may press the internal electrode 4 against the inner surface of the inner tube 2 . Alternatively, an elastic member may be provided inside the internal electrode 4 and the internal electrode 4 may be pressed against the inner surface of the inner tube 2 by the elastic force of the elastic member.

Also, the internal electrode 4 can be made of a material having a high reflectance with respect to the ultraviolet rays generated in the discharge space 9 . The internal electrodes 4 are made of, for example, a material that is conductive and highly reflective to ultraviolet rays. The internal electrodes 4 are made of metal such as stainless steel, aluminum, and aluminum alloys.

If the internal electrode 4 is made of a material having a high reflectance with respect to ultraviolet rays, the ultraviolet rays generated in the discharge space 9 and directed toward the inside of the inner tube 2 are reflected toward the outside of the barrier discharge lamp 1 (outer tube 3). be able to. Therefore, the extraction efficiency of ultraviolet rays generated in the discharge space 9 can be improved.

The external electrode 5 is provided outside the outer tube 3 . As shown in FIG. 2 , the external electrode 5 is provided on the outer surface of the reflective electrode 8 and the outer surface of the outer tube 3 exposed from the reflective electrode 8 . The external electrode 5 faces the internal electrode 4 with the discharge space 9 interposed therebetween. In this case, when the gap between the external electrode 5 and the outer surface of the reflective electrode 8 and the gap between the external electrode 5 and the outer surface of the outer tube 3 exposed from the reflective electrode 8 increase, the power to the discharge space 9 increases. There is a risk that the amount of supply of Therefore, it is preferable to bring the external electrode 5 into close contact with the outer surface of the reflective electrode 8 and the outer surface of the outer tube 3 exposed from the reflective electrode 8 .

The ultraviolet rays generated in the discharge space 9 are irradiated outside through the outer tube 3 and the outer electrode 5 . Therefore, the external electrode 5 has a structure that allows transmission of ultraviolet rays. The external electrode 5 has, for example, a mesh shape. The mesh-shaped external electrode 5 can be formed, for example, by weaving a metal wire into a seamless cylindrical shape. The metal wire is, for example, a wire containing Monel, a wire containing stainless steel, or the like.

The outer tube 3 provided with the reflective electrode 8 is inserted inside the cylindrical mesh-like outer electrode 5 . If the mesh-shaped external electrode 5 is used, it becomes easy to bring the external electrode 5 into close contact with the outer surface of the reflective electrode 8 and the outer surface of the outer tube 3 . In addition, the ultraviolet rays generated in the discharge space 9 can be irradiated to the outside through the spaces between the meshes. Further, if the external electrode 5 including the metal wire is provided on the outer surface of the outer tube 3, it becomes easy to release the heat generated together with the ultraviolet rays in the discharge space 9 to the outside.

For example, one set of leads 6 can be provided.
For example, one lead 6a has a wiring 6a1 and a connection terminal 6a2. One end of the wiring 6a1 is electrically connected to the external electrode 5 via the connection terminal 6a2. The other end of the wiring 6a1 is electrically connected to a lighting circuit, a power source, etc. provided outside the barrier discharge lamp 1. FIG.

For example, the other lead 6b has a wiring 6b1 and a connection terminal 6b2. One end of the wiring 6b1 is electrically connected to the internal electrode 4 via the connection terminal 6b2. The other end of the wiring 6b1 is electrically connected to a lighting circuit, a power source, etc. provided outside the barrier discharge lamp 1. FIG.

Incidentally, as shown in FIG. 1, the lead 6a can be provided only on one end side of the outer tube 3. As shown in FIG. Also, the leads 6a can be provided at both ends of the outer tube 3, respectively. For example, when the length of the outer tube 3 is long, that is, when the length of the external electrode 5 is long, it is preferable to provide leads 6a on both end sides of the outer tube 3 respectively.

As shown in FIG. 1, the lead 6b can be provided only on one end side of the inner tube 2. As shown in FIG. Also, the leads 6b can be provided at both ends of the inner tube 2, respectively. For example, if the inner tube 2 is long, that is, if the internal electrode 4 is long, it is preferable to provide leads 6b on both ends of the inner tube 2 .

Holders 7 are provided at both ends of the outer tube 3 (inner tube 2). The holder 7 covers the end of the outer tube 3 (inner tube 2). The holder 7 is made of an insulating material. The holder 7 is made of resin or inorganic material, for example. Inorganic materials are, for example, steatite, aluminum oxide, and the like. The holder 7 may be in contact with the external electrode 5 or may be separated from the external electrode 5 .

Here, as described above, since the external electrode 5 has a mesh shape, the ultraviolet rays generated in the discharge space 9 can be irradiated to the outside through the spaces between the meshes. However, if the mesh-like external electrode 5 is used, the area of the portion formed from the metal wire is reduced, so that the discharge area of the lamp is reduced. When the discharge area of the lamp is reduced, it becomes difficult to increase the amount of ultraviolet light generated in the discharge space 9 and, by extension, the amount of ultraviolet light irradiated to the outside of the barrier discharge lamp 1 .

Therefore, the reflective electrode 8 is provided in the barrier discharge lamp 1 according to this embodiment.
As shown in FIGS. 1 and 2 , the reflecting electrode 8 has a plate shape and is provided outside the outer tube 3 . The reflective electrode 8 can be provided on a part of the outer surface of the outer tube 3, for example.
That is, the reflective electrode 8 has a plate shape and is provided between the outer surface of the outer tube 3 and the external electrode 5 .

As described above, the external electrode 5 is provided on the outer surface of the reflective electrode 8 . Therefore, if the reflective electrode 8 is made of a conductive material such as metal, the reflective electrode 8 functions as part of the external electrode 5 . In this case, since the reflective electrode 8 has a plate shape, if the reflective electrode 8 functions as a part of the external electrode 5, the discharge area of the lamp can be increased. Therefore, the amount of ultraviolet light generated in the discharge space 9 and, in turn, the amount of ultraviolet light irradiated to the outside of the barrier discharge lamp 1 can be increased.

In this case, if the gap between the reflective electrode 8 and the outer surface of the outer tube 3 becomes large, the amount of power supplied to the discharge space 9 may vary. Therefore, it is preferable that the reflective electrode 8 is brought into close contact with the outer surface of the outer tube 3 . As shown in FIG. 2, for example, the reflective electrode 8 is provided on a part of the outer surface of the outer tube 3, so that the elastic force of the reflective electrode 8 may bring the reflective electrode 8 into close contact with the outer surface of the outer tube 3. .

Further, if the reflecting electrode 8 containing metal is provided on the outer surface of the outer tube 3, it becomes easy to release the heat generated together with the ultraviolet rays in the discharge space 9 to the outside.
In this case, if the thickness T (mm) of the reflective electrode 8 is too small, damage and deformation tend to occur during processing. On the other hand, if the thickness T (mm) of the reflective electrode 8 is too large, heat dissipation to the outside becomes poor, and discoloration and deterioration of the reflective electrode 8 tend to occur.
Therefore, the thickness T (mm) of the reflective electrode 8 is preferably set to "0.1 (mm) ≤ T (mm) ≤ 3.0 (mm)". With the reflective electrode 8 having such a thickness, good workability and heat dissipation can be obtained.

As described above, if the reflective electrode 8 has a plate shape, the discharge area of the lamp can be increased. However, when the plate-shaped reflective electrode 8 is provided, the ultraviolet rays generated in the discharge space 9 are shielded by the reflective electrode 8, so that the amount of ultraviolet rays irradiated to the outside of the barrier discharge lamp 1 is reduced. It will be.

In this case, the barrier discharge lamp 1 is often used, for example, for surface treatment such as removal of organic matter adhering to the surface of an object (light cleaning treatment), surface modification, and formation of an oxide film. Therefore, it is not necessary to increase the amount of ultraviolet light in all directions of the barrier discharge lamp 1, and it is sufficient to increase the amount of ultraviolet light in a predetermined direction.

As shown in FIG. 2, since the reflective electrode 8 is provided on a part of the outer surface of the outer tube 3, ultraviolet rays of the barrier discharge lamp 1 are emitted from the portion of the outer tube 3 where the reflective electrode 8 is not provided. It can be irradiated to the outside.

In this case, if the reflective electrode 8 has a high reflectance with respect to ultraviolet rays, the ultraviolet rays incident on the reflective electrode 8 can be efficiently reflected. Therefore, it is possible to increase the amount of ultraviolet light emitted from the portion of the outer tube 3 where the reflecting electrode 8 is not provided. That is, the reflective electrode 8 can also function as a reflective film that reflects ultraviolet rays. If the reflective electrode 8 functions as a reflective film, the extraction efficiency of ultraviolet rays generated in the discharge space 9 can be improved.

For example, if the reflective electrode 8 is made of a material that is conductive and highly reflective to ultraviolet rays, the reflective electrode 8 can function as part of the external electrode 5 and as a reflective film. For example, the reflective electrode 8 can be made of metal such as stainless steel, aluminum, and aluminum alloy. In this case, for example, if the reflective electrode 8 is formed of an aluminum plate subjected to electrolytic polishing, the function of the reflective electrode 8 as a part of the external electrode 5 and the function as a reflective film can be improved. can be done.

As shown in FIG. 2, when viewed from the direction along the tube axis of the outer tube 3, when the center angle θ of the surface (inner surface) of the reflective electrode 8 on the outer tube 3 side becomes small, the reflective electrode 8 and The area facing the internal electrode 4 becomes smaller, and the discharge area of the lamp becomes smaller. Therefore, the amount of ultraviolet light generated in the discharge space 9 is reduced. In addition, since the area of the inner surface of the reflective electrode 8 (the area of the ultraviolet ray reflecting surface) is also reduced, the amount of reflected ultraviolet rays is also reduced. Therefore, if the central angle .theta.

On the other hand, when the central angle .theta. increases, the area where the reflection electrode 8 and the internal electrode 4 face each other increases, and the discharge area of the lamp increases. Therefore, the amount of ultraviolet light generated in the discharge space 9 increases. In addition, since the area of the reflective electrode 8 is also increased, the amount of reflected ultraviolet rays is also increased. However, if the central angle .theta.

FIG. 3 is a graph for illustrating the relationship between the center angle θ of the reflective electrode 8 and the rate of increase of ultraviolet rays irradiated to the outside of the barrier discharge lamp 1 .
3 shows the case where the gas enclosed in the discharge space 9 is xenon. The sealing pressure was about 50 kPa. The peak wavelength of the generated ultraviolet rays is about 172 nm. A power pulse of 11.5 kHz and 500 W was applied to the reflecting electrode 8 and the internal electrode 4 .

As can be seen from FIG. 3, if the central angle θ is set to "15°≦θ", the discharge area of the lamp and the area of the ultraviolet ray reflecting surface are increased, so that the amount of ultraviolet light can be increased. . Moreover, if "θ≦240°" is satisfied, it is possible to suppress a decrease in the amount of ultraviolet light due to a decrease in the area of the portion of the outer tube 3 where the reflecting electrode 8 is not provided.
Therefore, by setting "15°≦θ≦240°", the amount of ultraviolet light emitted to the outside of the barrier discharge lamp 1 can be increased.

As described above, since the barrier discharge lamp 1 according to the present embodiment is provided with the reflective electrode 8 , even when the mesh-like external electrode 5 is provided, the external electrode 5 is not outside the barrier discharge lamp 1 . It is possible to increase the amount of ultraviolet light to be irradiated.
Further, when the center angle θ of the reflecting electrode 8 is set to 15°≦θ≦240° when viewed from the direction along the tube axis of the outer tube 3, the ultraviolet rays emitted to the outside of the barrier discharge lamp 1 can further increase the amount of light.

Although some embodiments of the present invention have been illustrated above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, etc. can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof. Moreover, each of the above-described embodiments can be implemented in combination with each other.

1 barrier discharge lamp, 2 inner tube, 3 outer tube, 4 inner electrode, 5 outer electrode, 8 reflective electrode, 9 discharge space

Claims (3)

an outer tube having a cylindrical shape;
a cylindrical inner tube provided inside the outer tube substantially coaxially with the outer tube via a gas-filled discharge space;
an external electrode provided outside the outer tube and having a mesh shape;
an internal electrode provided inside the inner tube;
a plate-like reflective electrode provided between the outer surface of the outer tube and the outer electrode;
A barrier discharge lamp comprising: 2. The barrier discharge lamp according to claim 1, wherein a central angle .theta.
15°≤θ≤240° The reflective electrode contains aluminum,
3. The barrier discharge lamp according to claim 1, wherein the following expression is satisfied, where T (mm) is the thickness of the reflecting electrode.
0.1 (mm) ≤ T (mm) ≤ 3.0 (mm)

Images