JP2021125437A - Barrier discharge lamp module, barrier discharge lamp, and ultraviolet radiation device - Google Patents

Abstract

To provide a barrier discharge lamp module, barrier discharge lamp and ultraviolet radiation device, capable of suppressing degradation in the transmission coefficient of ultraviolet radiation in a luminous tube.SOLUTION: A barrier discharge lamp module is tubular and includes a luminous tube whose internal space is sealed with gas and an internal electrode with a coil provided in the internal space. The luminous tube includes a material through which ultraviolet radiation runs and which contains SiO2. The content of an OH group in the material is 800 ppm and more to 2000 ppm or less.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a barrier discharge lamp module, a barrier discharge lamp, and an ultraviolet irradiation device.

There is a barrier discharge lamp that irradiates ultraviolet rays having a wavelength of 200 nm or less. Barrier discharge lamps are used for surface treatments such as removal of organic substances adhering to the surface of an object (light cleaning treatment), surface modification, and formation of an oxide film. The barrier discharge lamp has, for example, a pair of electrodes and a light emitting tube provided between the electrodes and formed of a dielectric material. When an AC voltage is applied to the pair of electrodes, a dielectric barrier discharge occurs, and ultraviolet rays having a specific wavelength are irradiated depending on the type of gas enclosed inside the arc tube.

Here, the ultraviolet rays are generated inside the arc tube and are irradiated to the outside through the arc tube. Therefore, when ultraviolet rays are irradiated for a long time, the chemical structure of the material of the arc tube may change, and the transmittance of the ultraviolet rays in the arc tube may be significantly lowered.
Therefore, it has been desired to develop a technique capable of suppressing a decrease in the transmittance of ultraviolet rays in the arc tube.

Japanese Unexamined Patent Publication No. 2002-093377

An object to be solved by the present invention is to provide a barrier discharge lamp module, a barrier discharge lamp, and an ultraviolet irradiation device capable of suppressing a decrease in the transmittance of ultraviolet rays in an arc tube.

The barrier discharge lamp module according to the embodiment has a tubular shape and includes an arc tube in which a gas is sealed in an internal space; an internal electrode having a coil provided in the internal space; It contains a material that transmits ultraviolet rays and _{contains SiO 2,} and the content of OH groups in the material is 800 ppm or more and 2000 ppm or less.

According to the embodiment of the present invention, it is possible to provide a barrier discharge lamp module, a barrier discharge lamp, and an ultraviolet irradiation device capable of suppressing a decrease in the transmittance of ultraviolet rays in the arc tube.

It is a schematic diagram for exemplifying the barrier discharge lamp which concerns on this embodiment. It is a schematic cross-sectional view of the barrier discharge lamp in FIG. 1 in the direction of line AA. It is a graph for exemplifying the relationship between the content of OH groups and the illuminance maintenance rate. It is a graph for exemplifying the relationship between the content of OH groups and the initial illuminance. It is a schematic diagram for exemplifying the structure of the ultraviolet irradiation apparatus.

Hereinafter, embodiments will be illustrated with reference to the drawings. In each drawing, similar components are designated by the same reference numerals and detailed description thereof will be omitted as appropriate. Further, the arrows X, Y, and Z in each drawing represent three directions orthogonal to each other. For example, the irradiation direction is the Z direction.

(Barrier discharge lamp module 10 and barrier discharge lamp 1)
FIG. 1 is a schematic diagram for exemplifying the barrier discharge lamp 1 according to the present embodiment.
FIG. 2 is a schematic cross-sectional view of the barrier discharge lamp 1 in FIG. 1 in the AA line direction.

As shown in FIGS. 1 and 2, the barrier discharge lamp 1 may be provided with the barrier discharge lamp module 10 and the external electrode 20.
The barrier discharge lamp module 10 can have an arc tube 11, an internal electrode 12, a reflective film 13, a holder 14, and a lead wire 15.

The arc tube 11 has a tubular shape and has a form in which the total length (length in the tube axis direction) is longer than the tube diameter. The arc tube 11 can be, for example, a cylindrical tube. Sealing portions 11a are provided at each of the ends of the arc tube 11 on both sides in the tube axis direction. By providing the sealing portion 11a, the internal space of the arc tube 11 can be hermetically sealed. The sealing portion 11a can be formed by using, for example, a pinch sealing method or a shrink sealing method.

Further, a conductive portion 11b and an outer lead 11c can be provided inside each sealing portion 11a. One conductive portion 11b can be provided for one sealing portion 11a. The planar shape of the conductive portion 11b can be a quadrangle. The conductive portion 11b has a thin film shape. The conductive portion 11b can be formed from, for example, a molybdenum foil.

The outer lead 11c has a linear shape and can be provided at least on the sealing portion 11a on the side where the lead wire 15 is provided. One end of the outer lead 11c is electrically connected to the conductive portion 11b. The vicinity of the end portion of the outer lead 11c can be laser welded or resistance welded to the conductive portion 11b. The other end of the outer lead 11c can be exposed from the sealing portion 11a. The outer lead 11c may contain, for example, molybdenum.

Gas is sealed in the internal space of the arc tube 11. In the barrier discharge lamp 1, a barrier discharge is performed between the internal electrode 12 and the external electrode 20 to give high energy electrons to the enclosed gas to generate excimer-excited molecules. When the excimer-excited molecules return to their original state, light having a specific peak wavelength is generated depending on the type of gas. Therefore, the gas sealed in the internal space of the arc tube 11 can be appropriately changed according to the application of the barrier discharge lamp 1. The gas sealed in the internal space of the arc tube 11 can be, for example, a rare gas such as krypton, xenon, argon, or neon, or a mixed gas in which a plurality of types of rare gases are mixed. The gas may further include halogen gas and the like, if necessary.

The gas pressure (filling pressure) at 25 ° C. in the internal space of the arc tube 11 can be, for example, about 80 kPa to 200 kPa. The gas pressure (filling pressure) at 25 ° C. in the internal space of the arc tube 11 can be determined from the standard state of gas (SATP (Standard Ambient Temperature and Pressure): temperature 25 ° C., 1 bar).

For example, when the surface of a glass plate for a flat panel display is light-cleaned, it is preferable that the gas to be sealed is xenon. The encapsulation pressure of xenon can be, for example, about 93 kPa. If the gas to be sealed is xenon, ultraviolet rays having a peak wavelength of 172 nm can be generated, so that the cleaning effect can be enhanced.

The internal electrode 12 can have a coil 12a and a leg 12b. The coil 12a and the leg 12b can be integrally formed. The coil 12a and the leg 12b can be formed by plastic working the wire rod. The wire diameter (diameter) of the wire rod can be, for example, about 0.2 mm to 1.0 mm.

The coil 12a and the leg 12b can contain, for example, tungsten as a main component. The tungsten content can be, for example, 50 wt% or more. In this case, if doped tungsten in which potassium or the like is added to tungsten is used, the dimensional stability of the coil 12a can be improved.

The coil 12a has a spiral shape and is provided in the internal space of the arc tube 11. The coil 12a extends a central region of the internal space of the arc tube 11 along the tube axis of the arc tube 11. The pitch dimension P of the coil 12a can be, for example, about 10 mm to 120 mm.

As shown in FIG. 2, the gap S between the coil 12a and the inner wall of the arc tube 11 is preferably 10 mm or less in the direction orthogonal to the tube axis direction of the arc tube 11. The coil 12a may be brought into contact with the reflective film 13 without providing the gap S. Further, when the reflective film 13 is not provided, the coil 12a and the inner wall of the arc tube 11 may be brought into contact with each other. When the gap S is equal to or less than a predetermined dimension, stable barrier discharge can be generated at a low voltage. Therefore, for example, the outer diameter dimension of the coil 12a can be set so that a predetermined gap S is provided according to the inner diameter dimension of the arc tube 11.

Legs 12b are provided at each of the ends on both sides of the coil 12a. The leg 12b has a linear shape and extends from the end of the coil 12a along the tube axis of the arc tube 11.

The end of the leg 12b is electrically connected to the conductive portion 11b inside the sealing portion 11a. The vicinity of the end of the leg 12b can be laser welded or resistance welded to the conductive portion 11b.

The reflective film 13 has a film shape and can be provided on the inner wall of the arc tube 11. The reflective film 13 can be provided between the external electrode 20 and the internal electrode 12 (coil 12a). The reflective film 13 is generated in the internal space of the arc tube 11 and reflects ultraviolet rays that do not go in the irradiation direction toward the irradiation direction. If the reflective film 13 is provided, the efficiency of extracting ultraviolet rays can be improved. Further, if the reflective film 13 is provided, the region of the arc tube 11 where the ultraviolet rays are directly incident can be reduced, so that the chemical structural change of the arc tube 11 described later can be suppressed.

As shown in FIG. 2, the reflective film 13 can be provided in a range in which the central angle θ1 is about 180 ° to 300 ° when viewed from the direction along the tube axis of the arc tube 11. The length L1 of the reflective film 13 in the tube axis direction can be equal to or greater than the length L2 of the coil 12a. By doing so, the efficiency of extracting ultraviolet rays can be effectively improved.

The thickness of the reflective film 13 can be, for example, about 100 μm to 300 μm. In this way, it becomes easy to maintain good reflectance to ultraviolet rays.
The reflective film 13 can contain, for example, SiO ₂ (silicon dioxide). Further, the reflective film 13 can also be formed by using a material containing ultraviolet scattering particles such as aluminum oxide.

The reflective film 13 is not always necessary and can be omitted. However, as described above, if the reflective film 13 is provided, the efficiency of extracting ultraviolet rays can be improved, and the chemical structural change of the arc tube 11 described later can be suppressed.

Holders 14 are provided at the ends of the arc tube 11 on both sides in the tube axis direction. The holder 14 covers the end of the arc tube 11. The holder 14 can be formed of, for example, an inorganic material such as resin or ceramics. The holder 14 can contain, for example, steatite, aluminum oxide, and the like. The holder 14 may be in contact with the external electrode 20 or may be provided at a distance from the external electrode 20.

The lead wire 15 can be electrically connected to the end of the outer lead 11c exposed from the sealing portion 11a. The lead wire 15 is electrically connected to the internal electrode 12 via the outer lead 11c and the conductive portion 11b. A lighting circuit 3 provided in the ultraviolet irradiation device 100 can be electrically connected to the lead wire 15 (see FIG. 5). As shown in FIG. 1, the lead wire 15 may be provided only on one end side of the arc tube 11, or may be provided on both end portions of the arc tube 11.

The external electrode 20 can be provided on the outside of the arc tube 11. The external electrode 20 extends along the tube axis of the arc tube 11. When the reflective film 13 is provided, the external electrode 20 can be provided at a position facing the reflective film 13.

If the gap between the surface of the external electrode 20 on the arc tube 11 side and the arc tube 11 is made too large, the efficiency of extracting ultraviolet rays may decrease. For example, when a barrier discharge occurs between the internal electrode 12 and the external electrode 20, if there is air in the environment in the gap between the internal electrode 12 and the external electrode 20, nitrifying hydrogen gas is generated. In addition, moisture in the environment may condense on the surface of the external electrode 20. When nitrifying hydrogen gas dissolves in the condensed water, nitric acid is produced. When nitric acid comes into contact with the outer surface of the arc tube 11, the transparency of ultraviolet rays decreases. If such a chemical reaction occurs repeatedly every time the barrier discharge lamp 1 is turned on, the efficiency of extracting ultraviolet rays may decrease over time.

On the other hand, if the gap between the surface of the external electrode 20 on the light emitting tube 11 side and the light emitting tube 11 is made too small, the barrier discharge lamp module 10 (light emitting tube 11) may be moved to the external electrode 20 due to dimensional tolerance or twist. It becomes difficult to attach to. In this case, if the external electrode 20 is forcibly expanded and the arc tube 11 is attached, a force is applied to the arc tube 11, and the life of the arc tube 11 may be shortened.

According to the findings obtained by the present inventor, when the radius of the arc tube 11 is R1 (mm) and the radius of curvature of the surface of the external electrode 20 on the arc tube 11 side is R2 (mm), "0.93". It is preferable that ≦ R1 / R2 ≦ 0.99 ”. By doing so, it is possible to suppress a decrease in the efficiency of extracting ultraviolet rays, and it is possible to facilitate the attachment of the barrier discharge lamp module 10.

Further, as shown in FIG. 2, when the central angle θ2 of the surface of the external electrode 20 on the arc tube 11 side is smaller than 30 ° when viewed from the direction along the tube axis of the arc tube 11, the external electrode 20 The region where the internal electrode 12 and the internal electrode 12 face each other becomes too small, and the amount of ultraviolet rays generated may decrease. On the other hand, when the central angle θ2 is larger than 190 °, the ultraviolet rays generated in the internal space of the arc tube 11 are easily absorbed by the external electrode 20, so that the efficiency of extracting the ultraviolet rays may decrease.

According to the knowledge obtained by the present inventor, it is preferable that the central angle θ2 is about 30 ° to 190 °. By doing so, it is possible to secure the required amount of ultraviolet rays generated, and it is possible to suppress a decrease in the efficiency of extracting ultraviolet rays.

The external electrode 20 can include a conductive material such as metal. The external electrode 20 can be formed of, for example, stainless steel, aluminum, or the like. Here, when the barrier discharge lamp 1 is turned on, heat is generated together with ultraviolet rays. Therefore, if the external electrode 20 is made of a material having high thermal conductivity such as metal, the external electrode 20 can also be used as a heat radiating portion.

The direction in which the barrier discharge lamp module 10 (light emitting tube 11) is attached to the external electrode 20 can be changed according to the central angle θ2. For example, when the central angle θ2 is 180 ° or less, the barrier discharge lamp module 10 (light emitting tube 11) can be attached from the Z direction or the Y direction. When the central angle θ2 exceeds 180 °, the barrier discharge lamp module 10 (light emitting tube 11) can be attached from the Y direction.

Although the case where the barrier discharge lamp module 10 (light emitting tube 11) can be removed from the external electrode 20 has been illustrated, the external electrode 20 may be fixed to the outer surface of the light emitting tube 11 and inserted. In this case, the arc tube 11, the internal electrode 12, the reflective film 13, and the like are more likely to be consumed than the external electrode 20. Therefore, it is preferable that the barrier discharge lamp module 10 (light emitting tube 11) can be removed from the external electrode 20. By doing so, it is possible to improve maintainability and reduce running costs.

Here, when the barrier discharge lamp 1 is turned on, ultraviolet rays are generated in the internal space of the arc tube 11. The generated ultraviolet rays are irradiated to the outside through the arc tube 11. Therefore, the arc tube 11 is formed of, for example, a material having a high transmittance of ultraviolet rays having a peak wavelength of 200 nm or less. The arc tube 11 can be formed of a material _{that transmits ultraviolet rays and contains SiO 2.} The arc tube 11 can be formed from, for example, synthetic quartz glass. However, when ultraviolet rays having a peak wavelength of 200 nm or less (for example, a peak wavelength of 172 nm) _{are incident on a material containing SiO 2} , the chemical structure of the material may change over time. For example, _{when ultraviolet rays are incident on SiO 2} , the bond between Si and O may be broken. Therefore, when the barrier discharge lamp 1 is turned on for a long time, a defect occurs in the chemical structure of the material of the arc tube 11, and the transmittance of ultraviolet rays is sharply lowered, and the amount of ultraviolet rays irradiated is sharply lowered. There is a risk of

According to the knowledge obtained by the present inventor, _{if the amount of OH groups contained in the material containing SiO 2} is increased, even if the bond between Si and O is broken due to the incident of ultraviolet rays, the chemical structure is defective. Can be repaired.

FIG. 3 is a graph for exemplifying the relationship between the content of OH groups and the illuminance maintenance rate.
As can be seen from FIG. 3, if the content of the OH group is 800 ppm or more, the initial illuminance can be maintained for a long time. This means that if the content of the OH group is 800 ppm or more, the decrease in the transmittance of ultraviolet rays in the arc tube 11 can be suppressed.

Further, according to other findings obtained by the present inventor, it has been found that if the content of OH groups is too large, the initial illuminance decreases.
FIG. 4 is a graph for exemplifying the relationship between the content of OH groups and the initial illuminance.
As can be seen from FIG. 4, when the content of OH groups exceeds 2000 ppm, the initial illuminance is significantly reduced. This means that if the content of OH groups is too high, the initial ultraviolet transmittance of the arc tube 11 will decrease.
Therefore, the content of OH groups is preferably 2000 ppm or less.

As described above, when the arc tube 11 _{contains a material containing SiO 2} (for example, synthetic quartz glass), the amount of OH groups contained in the material is more preferably 800 ppm or more and 2000 ppm or less. .. By doing so, the transmittance of ultraviolet rays in the arc tube 11 can be maintained for a long period of time, and the initial transmittance of ultraviolet rays in the arc tube 11 can be increased.

(Ultraviolet irradiation device 100)
Next, the ultraviolet irradiation device 100 according to the present embodiment will be illustrated.
In the following, the case where two of the above-mentioned barrier discharge lamps 1 are provided will be illustrated, but the number of barrier discharge lamps 1 can be appropriately changed depending on the application, the size of the irradiation target, and the like. That is, at least one barrier discharge lamp 1 may be provided.

FIG. 5 is a schematic diagram for exemplifying the configuration of the ultraviolet irradiation device 100.
As shown in FIG. 5, the ultraviolet irradiation device 100 may be provided with a barrier discharge lamp 1, a cooling unit 2, a lighting circuit 3, and a case 4.

The cooling unit 2 can face the arc tube 11 with the external electrode 20 interposed therebetween (see FIG. 2). The surface of the cooling unit 2 on the external electrode 20 side can be brought into close contact with the external electrode 20. The cooling unit 2 can be formed of a material having high thermal conductivity. The cooling unit 2 can be formed of, for example, a metal such as aluminum or stainless steel. Further, a flow path for flowing the refrigerant may be provided inside the cooling unit 2 to further improve heat dissipation. The cooling unit 2 may be integrated with the external electrode 20. Further, if necessary, the cooling unit 2 and the external electrode 20 may be insulated from each other. The cooling unit 2 can also hold the holder 14.

The lighting circuit 3 can be electrically connected to the internal electrode 12 and the external electrode 20. The lighting circuit 3 can have an inverter that converts the power from the AC power source into high voltage and high frequency (for example, a sine wave having a frequency of 37 kHz). For example, the lighting circuit 3 can light the barrier discharge lamp 1 with a lamp power of about 2.4 kW.

The case 4 has a box shape, and the barrier discharge lamp 1, the cooling unit 2, and the lighting circuit 3 can be housed therein. An opening 4a is provided on one surface of the case 4 so that the ultraviolet rays emitted from the barrier discharge lamp 1 are irradiated to the outside.

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

1 Barrier discharge lamp, 3 Lighting circuit, 10 Barrier discharge lamp module, 11 arc tube, 12 internal electrode, 12a coil, 13 reflective film, 20 external electrode, 100 UV irradiation device

Claims (5)

An arc tube that has a tubular shape and is filled with gas in the internal space;
With an internal electrode having a coil provided in the internal space;
Equipped with
The arc tube contains a material that transmits ultraviolet rays and _{contains SiO 2,} and the material has an OH group content of 800 ppm or more and 2000 ppm or less. The barrier discharge lamp module according to claim 1, wherein the material is synthetic quartz glass and the gas contains xenon. The barrier discharge lamp module according to claim 1 or 2, further comprising a reflective film that is provided on the inner wall of the arc tube and reflects the ultraviolet rays. With the barrier discharge lamp module according to any one of claims 1 to 3.
With an external electrode provided on the outside of the arc tube provided in the barrier discharge lamp module;
Barrier discharge lamp equipped with. With the barrier discharge lamp according to claim 4;
An internal electrode provided in the barrier discharge lamp, an external electrode, and a lighting circuit electrically connected to the external electrode;
An ultraviolet irradiation device equipped with.

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