JP2022118799A - barrier discharge lamp - Google Patents

Abstract

To provide a barrier discharge lamp capable of improving startability.SOLUTION: A barrier discharge lamp comprises: a cylindrical outer pipe; a cylindrical inner pipe that is provided inside the outer pipe substantially coaxially with the outer pipe via a discharge space in which gas is sealed; a mesh-like external electrode provided outside the outer pipe; an internal electrode provided inside the inner pipe; a first protrusion provided on an inner surface of the outer pipe: and a second protrusion that is provided on an outer surface of the inner pipe and faces the first protrusion. The barrier discharge lamp satisfies an expression 0 mm<d≤50 mm, where d (mm) is a distance between a tip of the first protrusion and a tip of the second protrusion.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, when electrodes are provided on the inner surface of the inner tube and the outer surface of the outer tube, the distance between the electrodes increases, which makes it difficult to start the barrier discharge lamp. In addition, when the gas is filled in the discharge space, if the pressure of the gas is varied, or if an impure gas (such as water vapor) is mixed into the gas, it may become more difficult to start the barrier discharge lamp.

Therefore, a technique has been proposed in which a getter that adsorbs impure gases is provided in the discharge space.
However, even if the getter is provided, there is still room for improvement in the startability of the barrier discharge lamp.

JP-A-6-310103 JP-A-10-241633

SUMMARY OF THE INVENTION An object of the present invention is to provide a barrier discharge lamp capable of improving startability.

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-shaped external electrode provided outside the outer tube; an internal electrode provided inside the inner tube; and a first protrusion provided on the inner surface of the outer tube: and a second protrusion provided on the outer surface of the inner tube and opposed to the first protrusion. The barrier discharge lamp satisfies the following formula, where d (mm) is the distance between the tip of the first projection and the tip of the second projection. 0mm<d≦50mm

According to the embodiments of the present invention, it is possible to provide a barrier discharge lamp capable of improving startability.

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. 4 is a graph for illustrating the relationship between distance d (mm) and starting voltage; FIG. 4 is a schematic cross-sectional view for illustrating a barrier discharge lamp according to another embodiment; 5 is a schematic cross-sectional view of the barrier discharge lamp in FIG. 4 taken along line BB. FIG.

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 an inner tube 2, an outer tube 3, an inner electrode 4, an outer electrode 5, a lead 6, a holder 7, and a dielectric discharge portion 8, for example.

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 can be, 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 can be, 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 can be 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 can be 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, and high-energy electrons are given 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) at 25° C. in the discharge space 9 can be, for example, about 80 kPa to 200 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 93 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 electrodes 4 can be made of metal such as stainless steel or aluminum, for example. 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 may adhere to the inner surface of the inner tube 2 by elastic force. Alternatively, an elastic member may be provided inside the internal electrode 4 to press the internal electrode 4 against the inner surface of the inner tube 2 .

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 can be made of, for example, aluminum or an aluminum alloy. 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 . The external electrode 5 can be provided on the outer surface of the outer tube 3 . The external electrode 5 faces the internal electrode 4 with the discharge space 9 interposed therebetween. In this case, if the gap between the external electrode 5 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 to bring the external electrode 5 into close contact with the outer surface of the outer tube 3 .

As described above, the ultraviolet rays generated in the discharge space 9 are irradiated outside through the outer tube 3 . 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-like external electrode 5 can be formed, for example, by weaving a metal wire into a seamless cylindrical shape. The metal wire can be, for example, a wire containing Monel, a wire containing stainless steel, or the like.

The outer tube 3 is inserted inside the cylindrical mesh-like external 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 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.

As shown in FIG. 1, the leads 6a can be provided only on one end of the outer tube 3, or can be provided on both ends of the outer tube 3, respectively. For example, if the outer tube 3 is long, that is, if the external electrode 5 is long, it is preferable to provide leads 6a at both ends of the outer tube 3 .

As shown in FIG. 1, the leads 6b can be provided only at one end of the inner tube 2, or 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 at both ends of the inner tube 2, respectively.

The 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 can be made from an insulating material. The holder 7 can be made of resin or inorganic material, for example. The inorganic material can be, 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 .

As described above, for example, the inner electrode 4 is provided on the inner surface of the inner tube 2 and the outer electrode 5 is provided on the outer surface of the outer tube 3 . As a result, the distance between the internal electrode 4 and the external electrode 5 becomes long, which may make it difficult to start the barrier discharge lamp 1 . In this case, if the distance between the inner tube 2 and the outer tube 3 is shortened, the discharge space 9 becomes smaller, so there is a possibility that the amount of generated ultraviolet light will be reduced. Furthermore, when the discharge space 9 is filled with gas, if the pressure of the gas fluctuates or impure gas (such as water vapor) is mixed, it may become more difficult to start the barrier discharge lamp.

Therefore, the dielectric discharge section 8 is provided in the barrier discharge lamp 1 according to this embodiment. As shown in FIGS. 1 and 2, the dielectric discharge section 8 is provided inside the discharge space 9 . The dielectric discharge portion 8 has, for example, a convex portion 8a (corresponding to an example of a first convex portion) and a convex portion 8b (corresponding to an example of a second convex portion).

The convex portion 8 a is provided on the inner surface of the outer tube 3 . For example, the convex portion 8a can be adhered to the inner surface of the outer tube 3 . The convex portion 8 a protrudes from the inner surface of the outer tube 3 toward the outer surface of the inner tube 2 . The cross-sectional area of the protrusion 8a on the outer tube 3 side is larger than the cross-sectional area of the protrusion 8a on the inner tube 2 side. In this case, the projection 8a preferably has a shape with a sharp tip. The shape of the convex portion 8a can be, for example, a cone, a truncated cone, a pyramid, a truncated pyramid, or the like.

The convex portion 8b is provided on the outer surface of the inner tube 2. As shown in FIG. For example, the protrusion 8b can be adhered to the outer surface of the inner tube 2. As shown in FIG. The convex portion 8b is provided at a position facing the convex portion 8a. The convex portion 8 b protrudes from the outer surface of the inner tube 2 toward the inner surface of the outer tube 2 . The cross-sectional area of the protrusion 8b on the inner tube 2 side is larger than the cross-sectional area of the protrusion 8b on the outer tube 3 side. In this case, it is preferable that the convex portion 8b has a shape with a sharp tip. The shape of the convex portion 8b can be, for example, a cone, a truncated cone, a pyramid, a truncated pyramid, or the like.

The material of the protrusions 8a and 8b can be conductive. Moreover, it is preferable that the material of the protrusions 8a and 8b be easily adhered to the inner tube 2 and the outer tube 3 made of synthetic quartz glass or the like. Moreover, it is preferable that the material of the projections 8a and 8b be a material that does not easily absorb the ultraviolet rays generated in the discharge space 9, for example, a material that is translucent. For example, the convex portion 8a and the convex portion 8b may contain ITO (Indium Tin Oxide) or the like.

If the protrusions 8a and 8b are provided, discharge is likely to occur between the protrusions 8a and 8b when a voltage is applied to the internal electrode 4 and the external electrode 5. FIG. In this case, if the tips of the protrusions 8a and 8b are sharp, the electric field strength at the tips of the protrusions 8a and 8b can be increased, so that the discharge between the protrusions 8a and 8b can be increased. becomes more likely to occur.

Here, the discharge between the convex portion 8a and the convex portion 8b depends on the pressure of the gas (for example, xenon) enclosed in the discharge space 9 and the distance between the tip of the convex portion 8a and the tip of the convex portion 8b. Affected by d (mm). In the case of a general barrier discharge lamp 1, the pressure of gas charged in the discharge space 9 is, for example, about 80 kPa to 200 kPa.

As a result of investigation, the present inventor found that the distance d (mm) between the tip of the projection 8a and the tip of the projection 8b is defined as "0 mm<d≦ 50 mm", the discharge between the projections 8a and 8b is facilitated, and it has been found that the starting voltage can be reduced to 5 kV or less. That is, if "0 mm<d≦50 mm", the startability of the barrier discharge lamp 1 can be improved.

In addition, when the gas is sealed in the discharge space 9, if the pressure of the gas varies or if an impure gas (for example, water vapor) is mixed, the starting of the barrier discharge lamp 1 becomes even more difficult. Also, starting performance can be improved by setting "0 mm<d≦50 mm".

FIG. 3 is a graph illustrating the relationship between the distance d (mm) between the tip of the projection 8a and the tip of the projection 8b and the starting voltage.
As can be seen from FIG. 3, the starting voltage can be reduced to 5 kV or less by setting the distance d (mm) to 50 mm or less. Therefore, the startability of the barrier discharge lamp 1 can be improved.
Note that the smaller the distance d (mm), the smaller the starting voltage. discharge will not occur. If no discharge occurs between the projections 8a and 8b, the startability of the barrier discharge lamp 1 cannot be improved. Therefore, the distance d (mm) is assumed to exceed 0 mm.

Also, in the above description, a case where one set of the convex portion 8a and the convex portion 8b is provided has been described, but a plurality of sets of the convex portion 8a and the convex portion 8b may be provided.

FIG. 4 is a schematic cross-sectional view for illustrating a barrier discharge lamp 1a according to another embodiment.
FIG. 5 is a schematic cross-sectional view of the barrier discharge lamp 1a in FIG. 4 taken along line BB.
As shown in FIGS. 4 and 5, the barrier discharge lamp 1a includes, for example, an inner tube 2, an outer tube 3, an inner electrode 4, an outer electrode 5, a lead 6, a holder 7, a dielectric discharge portion 8, and a reflector 10. have.

That is, the barrier discharge lamp 1a can be the barrier discharge lamp 1 described above further provided with a reflecting portion 10 .

The reflecting portion 10 can be provided between the internal electrode 4 and the inner surface of the inner tube 2 . The reflector 10 can be provided on the inner surface of the inner tube 2 . The reflecting portion 10 is made of a material having a high reflectance with respect to ultraviolet rays generated in the discharge space 9 . The reflector 10 can be made of, for example, aluminum or an aluminum alloy.

If the reflecting portion 10 is provided, the ultraviolet rays generated in the discharge space 9 and directed to the inside of the inner tube 2 can be reflected toward the outside of the barrier discharge lamp 1 (outer tube 3). Therefore, the extraction efficiency of ultraviolet rays generated in the discharge space 9 can be improved.

Here, if there is a gap between the reflecting portion 10 and the inner surface of the inner tube 2, reflection of ultraviolet rays may be suppressed. Since the reflecting portion 10 only needs to reflect ultraviolet rays, the thickness can be reduced. If the thickness is thin, it becomes easy to bring the reflecting portion 10 and the inner surface of the inner tube 2 into close contact with each other. For example, the reflecting portion 10 can be formed on the inner surface of the inner tube 2 using a film forming method such as sputtering.

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.

Reference Signs List 1 barrier discharge lamp 1a barrier discharge lamp 2 inner tube 3 outer tube 4 inner electrode 5 outer electrode 8 dielectric discharge portion 8a convex portion 8b convex portion 9 discharge space 10 reflecting portion

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 first projection provided on the inner surface of the outer tube:
A second convex portion provided on the outer surface of the inner tube and facing the first convex portion:
and
A barrier discharge lamp that satisfies the following equation, where d (mm) is the distance between the tip of the first projection and the tip of the second projection.
0mm<d≦50mm 2. The barrier discharge lamp of claim 1, wherein said first protrusion and said second protrusion comprise indium tin oxide. 3. The barrier discharge lamp according to claim 1, further comprising a reflector provided between said internal electrode and the inner surface of said inner tube.

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