JP7462524B2 - Excimer lamps, UV irradiation devices and ozone generators - Google Patents

Description

The present invention relates to an excimer lamp, an ultraviolet irradiation device equipped with an excimer lamp, and an ozone generator, and in particular to the configuration of the tip of the discharge vessel of the excimer lamp.

In an excimer lamp, a rare gas is sealed inside a discharge vessel (light emitting tube), and a voltage is applied between an outer electrode on the outer surface of the light emitting tube and an inner electrode inside the tube, causing a discharge and emitting excimer light. It is possible to irradiate ultraviolet light as the excimer light, and it can be used as a light source for generating ozone by irradiating ultraviolet light.

To reduce the starting voltage of an excimer lamp, an electrode arrangement is known in which the tip of the internal electrode extends into the tip portion formed at one end of the discharge vessel, and the external electrode extends to the outer surface of the tip portion (see Patent Document 1). This type of electrode arrangement can also be used in excimer lamps with a double tube structure (see Patent Document 2).

JP 2014-154274 A JP 2016-91618 A

While a high voltage is applied to the inner electrode of the excimer lamp, the tip portion is a remnant of the exhaust path inside the discharge vessel during the manufacturing process of the excimer lamp, and has a smaller inner diameter than the discharge vessel (outer tube). For this reason, dielectric breakdown is likely to occur between the inner electrode that extends to the tip tube tip and the outer electrode that extends to the outer surface of the tip portion. Dielectric breakdown is also likely to occur when a conductor with the same potential (earth) as the outer electrode is close to the tip portion.

Therefore, a discharge vessel configuration that suppresses the occurrence of insulation breakdown is required.

The excimer lamp of the present invention comprises a discharge vessel with a small diameter portion at its tip, an inner electrode provided within the discharge vessel, and an inner tube covering the inner electrode. The "tip" here corresponds to one end of the discharge vessel. The "small diameter portion" is a portion with a smaller diameter than the constant diameter portion of the discharge vessel, and the small diameter portion can be formed in various shapes along the axis of the discharge vessel (lamp axis). It is also possible to form a configuration in which it protrudes from the vessel end toward the tip side (outside the vessel), or a portion that protrudes partially toward the rear end side (inside the vessel).

The inner electrode can be configured to extend along the lamp axis, for example as a foil electrode. The inner tube can be tapered at its tip and embedded in the inner tube to concentrate the electric field.

In the present invention, the tip of the inner tube fits into the small diameter portion, and the tip of the inner electrode along the lamp axis is located rearward of the small diameter portion. There are various ways in which it fits into the small diameter portion, depending on the shape of the inner tube and the shape of the small diameter portion, etc.

For example, if the tip of the inner tube is tapered, at least a portion of the side of the tip can be configured to contact the inner surface of the small diameter portion. The contact portion of the small diameter portion that contacts at least a portion of the side of the tip can be curved.

The small diameter portion may also have a cylindrical portion that protrudes toward the outside and/or inside of the container, and the inner tube may be configured to contact the cylindrical portion.

For example, the distance between the tip of the inner tube and the tip of the inner electrode along the lamp axis can be configured to be greater than the distance between the inner electrode and the outer peripheral surface of the inner tube along the lamp diameter direction.

The distance along the lamp axis between the tip of the inner tube and the tip of the inner electrode may also be configured to be longer than the distance along the lamp axis between the tip of the inner tube and the tip of the small diameter portion.

The ultraviolet irradiation device according to one aspect of the present invention can be configured as a device having the characteristics of any of the above excimer lamps, and the excimer lamp is installed in the device housing with the outer electrode or a conductor having the same potential as the outer electrode in contact with or in close proximity to the small diameter portion or the end of the discharge vessel.

The ozone generator according to one aspect of the present invention can be configured as a device having the characteristics of any of the excimer lamps described above, and includes a support member that supports the excimer lamp, with its small diameter portion facing the intake fan, at the tip of the small diameter portion or the end of the discharge vessel, and has the same potential as the outer electrode.

The present invention makes it possible to suppress the occurrence of dielectric breakdown in excimer lamps, ozone generators equipped with excimer lamps, and the like.

1 is a diagram showing a schematic internal configuration of an irradiation device including an excimer lamp according to a first embodiment; FIG. 2 is an enlarged view showing the tip of an excimer lamp. FIG. 13 is a diagram showing a modified example of the discharge vessel according to the first embodiment. FIG. 11 is a view showing another modified example of the discharge container according to the first embodiment. FIG. 11 is a schematic configuration diagram of a Kisima lamp provided in an ultraviolet irradiation device according to a second embodiment.

Below, an embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows a schematic internal configuration of an ozone generator according to a first embodiment. Note that in Figure 1, the excimer lamp and the housing are depicted in cross section.

The ozone generator 100 includes an ultraviolet irradiation device that houses an excimer lamp 10 in a housing 100K, and the excimer lamp 10 is arranged so that its lamp axis E is aligned vertically. A blower (not shown) is installed below the excimer lamp 10, and gas sucked into the housing 100K flows vertically (lamp axis E) inside the housing 100K and flows out from an opening 100P on the top surface.

The excimer lamp 10 emits ultraviolet light, for example, ultraviolet light with a wavelength of 172 nm. When the ultraviolet light is irradiated onto the oxygen-containing gas flowing around the excimer lamp 10, ozone is generated, and the ozone-containing gas is released from the opening 100P. This allows for sterilization, disinfection, etc. to be performed.

The excimer lamp 10 is supported within the housing 100K by support members 70, 71, and 72. The support members 70, 71, and 72 are each attached to a wall portion 75 arranged within the housing 100K, and the support members 70 and 71 clamp the excimer lamp 10 via the outer electrode 50 so as to prevent displacement of the excimer lamp 10 mainly in the radial direction. The support member 72 supports one end (hereinafter referred to as the tip) of the excimer lamp 10 so as to prevent displacement of the excimer lamp 10 mainly in the axial direction.

The discharge vessel (light emitting tube) 10T of the excimer lamp 10 comprises an outer tube 20 made of a dielectric material such as quartz glass and having a generally cylindrical cross section. Inside the outer tube 20 is an inner tube 30 having a generally cylindrical cross section and in which a foil electrode (hereinafter referred to as the inner electrode) 40 extending along the tube axis, i.e., the lamp axis E, is embedded (covered). A rare gas such as xenon gas or a mixture of a rare gas and a halogen gas is sealed in the discharge space S within the discharge vessel 10T as a discharge gas.

The inner tube 30, which is a dielectric, is arranged coaxially with the outer tube 20 and is heat-welded to the rear end of the discharge vessel 10T to form a discharge space S. The inner electrode 40 is arranged within the inner tube 30, centered on the lamp axis E, as viewed from the end of the inner tube 30. The inner electrode 40 is not exposed to the discharge space S formed between the inner tube 30 and the outer tube 20. It is also possible to arrange the inner electrode within the inner tube, rather than embedding it by heat welding with the inner tube.

An outer electrode 50 is provided on the outer surface 20S of the outer tube 20. The outer electrode 50 is composed of a metal wire wound in a spiral shape, and a part of the wire is electrically connected to a power supply line (not shown) that connects to earth via the support members 70, 71 and the wall portion 75.

A power supply unit (not shown) is provided inside the housing 100K. The power supply unit converts commercial AC voltage to DC voltage, and converts the DC voltage to a high-frequency voltage using a switching circuit, which sends the voltage to the step-up transformer. The step-up transformer boosts the high-frequency voltage, and applies the high-frequency voltage between the inner electrode 40 and the outer electrode 50 through the power supply line 60. Alternatively, the power supply unit may be configured to convert commercial AC voltage to DC voltage using a frequency converter, which sends the voltage to the step-up transformer.

The discharge vessel 10T has protruding portions (hereinafter referred to as small diameter portions) 21, 22 at both ends of the constant inner diameter portion 20M that surrounds the discharge space S. The small diameter portion 22 is a portion of the rear end side of the inner tube 30 that is not covered by the outer tube 20 and protrudes along the lamp axis E toward the rear end of the lamp, and the power supply line 60 passes through the inside.

The small diameter portion 21 is formed during the lamp manufacturing process and protrudes from the discharge vessel 10T (outside the vessel) along the lamp axis E toward the lamp tip. Here, the tip side of the outer tube 20 is heated and deformed to reduce its diameter, and a tip tube with a smaller diameter than the outer tube 20 is welded to form the small diameter portion 21, which has a smaller diameter than the constant inner diameter portion 20M. The tip tube used in the lamp manufacturing process may be provided in a position separate from the small diameter portion.

In this embodiment, the tip 31 of the inner tube 30 enters the small diameter portion 21, and the tip 31 of the inner tube 30 contacts and is supported by the small diameter portion 21. While this fitted state is formed, the tip 41 of the inner electrode 40 does not enter into the small diameter portion 21. This will be described in detail below.

Figure 2 is an enlarged view showing the area near the small diameter portion of the discharge vessel 10T.

The tip 31 of the inner tube 30 is tapered, and here has a bullet-like shape. On the other hand, at the tip side of the outer tube 20, the tapered diameter section 20T, which tapers from the constant inner diameter section 20M to the small diameter section 21, is formed in a curved bowl shape, and the small diameter section 21 is formed so that it protrudes from its center.

The inner surface 21S of the reduced diameter portion 20T and small diameter portion 21 of the outer tube 20 has a continuous, smooth curved shape so that the connection between the reduced diameter portion 20T and the small diameter portion 21 is not visible. Two curvature change points Q11 and Q12 appear in the cross-sectional shape of the inner surface from the reduced diameter portion 20T to the small diameter portion 21 of the discharge vessel 10T.

When the curve along the inner cross-sectional shape of the discharge vessel 10T from the tapered portion 20T to the small diameter portion 21 is approximated by a circle (circle of curvature), the curvature change portion (change point) Q11 corresponds to the boundary position where the center of curvature of the circle of curvature moves from the discharge space S to the outside of the lamp. In other words, it corresponds to the boundary position where the inner cross-sectional shape part that is concave toward the discharge space S moves to the inner cross-sectional shape part that is concave toward the outside of the lamp.

On the other hand, the curvature change portion Q12 corresponds to the boundary position where the center of curvature of the curvature circle moves from the outside of the lamp back to the discharge space S side. In other words, it corresponds to the boundary position where the center of curvature of the curvature circle moves from the inner cross-sectional shape portion that is concave toward the outside of the lamp to the inner cross-sectional shape portion that is concave toward the discharge space S side.

When the small diameter portion 21 is defined using the curvature change portion Q11, the small diameter portion 21 indicates the portion in the axial range from the tip 21T of the discharge vessel 10T to the curvature change portion Q11, and has a length K1 along the lamp axis E. The narrowing portion 20T is formed toward the rear end of the discharge vessel 10T from the curvature change portion Q11, and indicates the portion that narrows in diameter toward the small diameter portion 21.

The inner tube 30, which is arranged vertically, is positioned by a part of the side surface (circumferential outer surface) 31S of its tip 31 contacting the contact portion 23, and is supported by the discharge vessel 10T. However, the contact portion 23 indicates the curved surface portion between the curvature change portions Q11 and Q12 of the small diameter portion 21. The distance L1 along the lamp axis E between the tip apex 31T of the inner tube 30 and the tip tube tip apex 21T is shorter than the distance L2 along the lamp axis E between the inner tube tip apex 31T of the inner tube 30 and the tip 41 of the inner electrode 40.

The distance L2 is longer than the shortest distance T between the edge 40L of the lamp radial end of the foil-shaped inner electrode 40 and the outer circumferential surface 30S of the inner tube 30. In other words, the insulation distance along the lamp axis E of the inner electrode 40 embedded in the inner tube 30 is longer than the insulation distance along the radial direction.

As described above, the excimer lamp 10 is supported by a support member 70 that is connected to earth at the tip apex 21T of the tip tube of the small diameter portion 21. The edge 40L of the foil-shaped inner electrode 40 is in a knife-edge shape that is sharpened from the center toward the edge in the width direction. When a high voltage is applied to an inner electrode 40 having such an electrode shape, electric field concentration occurs at the edge 40L (particularly the tip 41).

However, since the insulation distance is ensured as distance L2 (thickness of the inner tube 30 in the lamp axial direction) and distance L1 (distance in the lamp axial direction between the inner tube tip apex 31T and the tip tube tip apex 21T), it is possible to prevent insulation breakdown with the support member 70. As a result, discharge occurs well between the inner electrode 40 and the outer electrode 50, and ultraviolet rays are emitted from the entire discharge vessel 10T.

In this way, the tip 31 of the inner tube 30 reaches the internal space of the small diameter section 21 of the discharge vessel and is fitted into it, while the position along the lamp axis E of the tip 41 of the inner electrode 40 is located closer to the rear end (the center of the discharge vessel) than the small diameter section 21, without reaching the internal space of the small diameter section 21. Therefore, it is possible to include the length along the lamp axis E of the inner electrode 40 and the winding length of the outer electrode 50 up to the vicinity of the reduced diameter section 20T of the outer tube 20, and the light-emitting length can be increased without changing the overall length of the lamp.

In addition, because the inner tube 30 is supported in contact with the small diameter portion 21, the inner tube 30 can be held stably and coaxially within the outer tube 20, and because the inner surface of the small diameter portion, which is the contact portion 23, is curved, contact can be made without damaging the tip portion 31 of the inner tube 30. And because the tip portion 31 of the inner tube 30 is curved and tapered, contact can be made so that the inner tube 30 can be held stably and coaxially even with dimensional errors caused by the respective heat forming processes.

In the discharge vessel 10T, the portion along the lamp axis from the tapered portion 20T to the small diameter portion 21 contributes very little to the discharge (emission of ultraviolet rays). Therefore, it is possible to make the tapered portion 20T of the discharge vessel 10T substantially flat rather than having a curved, bowl-like shape.

Figure 3 shows a modified example of the discharge vessel in the first embodiment. The flat portion 20TM is formed as a substantially flat surface along a direction perpendicular to the lamp axis E (lamp radial direction). By shortening the length (protruding height) K1' of the small diameter portion 21-1 along the lamp axis E, a compact excimer lamp 10-1 can be constructed along the lamp axis E, and by bringing the discharge region closer to the reduced diameter portion 20T of the discharge vessel 10T, the light emission length relative to the overall lamp length can be increased.

Various configurations are possible for the inner tube 30 to be supported (positioned) in contact with the small diameter portion 21-1 of the discharge vessel 10T. For example, the inner diameter of the small diameter portion 21-1 may be made larger than the outer diameter of the tip portion 31 of the inner tube 30, and the inner tube tip apex 31T may be positioned closer to the tip tube tip apex 21T, so that the inner tube is supported in contact with the inner tube tip apex 31T side or the bottom 21B rather than the curvature change portion Q12 on the inner surface of the small diameter portion 21-1.

Also, on the inner surface of the small diameter portion 21-1, a cylindrical portion along the lamp axis E may be formed at the boundary position where the center of curvature of the curvature circle moves from the outside of the lamp to the discharge space S side, i.e., the inner surface portion where the curvature change portion Q12 is located, and the length (protruding height) K1' along the lamp axis E of the small diameter portion 21-1 may be lengthened, and the cylindrical portion may be in contact with the tip portion 31 and fitted. Furthermore, the tip portion 31 of the inner tube 30 may not be tapered or curved, and the small diameter portion inner surface may be tapered and fitted. In this case, the inner surface portion where the curvature change portions Q11 and Q12 are located does not have to be curved. It is sufficient that there is an axial range in which the tip portion 31 of the inner tube 30 and the small diameter portion 21-1 overlap in the radial direction.

Figure 4 shows another modified example of the discharge vessel of the first embodiment. Here, the small diameter portion 21-2 is formed so that one end thereof protrudes further along the lamp axis E toward the rear end of the lamp (inside the vessel) than the tip of the reduced diameter portion 20T. The small diameter portion 21-2 has a cylindrical portion that at least partially protrudes toward the discharge space, and the tip portion 31 of the inner tube 30 fits into the cylindrical portion of the small diameter portion 21-2. The side of the tip portion 31 may contact the inner surface of the small diameter portion 21-2, and the tip apex 31T may contact the inner surface of the bottom portion 21B of the small diameter portion 21-2. It is also possible for the tip portion 31 to protrude only inward, without protruding outward from the lamp.

Next, a second embodiment of an ultraviolet irradiation device equipped with an excimer lamp will be described with reference to FIG. 5. In the second embodiment, the outer electrode is provided up to the small diameter portion and is electrically connected to the power supply portion for the outer electrode via the small diameter portion.

Figure 5 is a schematic diagram showing the internal configuration of an excimer lamp in a second embodiment of an ultraviolet irradiation device.

The ultraviolet irradiation device 100' includes an excimer lamp 10'. Here, the excimer lamp 10' is disposed inside a light-transmitting jacket tube 11 that is installed laterally (horizontally) within the ultraviolet irradiation device housing (not shown), and the fluid to be irradiated with ultraviolet rays, such as cleaning water, flows around the outer periphery of the jacket tube 11.

An outer electrode 50' made of a metal film such as an aluminum film is provided on the outer surface 20'S of the discharge vessel 10'T. The outer electrode 50' covers the entire outer surface at both ends of the discharge vessel 10'T, but only covers a portion of the surface of the constant diameter portion 20'M between them so as not to interfere with ultraviolet radiation. The outer electrode 50' covering the small diameter portion 21' is connected to the outer electrode power supply line via a metal socket or the like (not shown). Note that the thickness of the outer electrode 50' is exaggerated in Figure 3.

As in the first embodiment, the range of the small diameter section 21' can be defined using the curvature change portion in the cross-sectional view. The inner surface connecting the constant inner diameter portion 20'M of the outer tube 20' to the small diameter section 21' via the reduced diameter portion 20'T has a continuous, smooth curved shape, and the cross section has curvature change portions Q20, Q21, Q22, and Q23. The small diameter section 21' has a cylindrical portion.

The curvature-changing portion Q20 is the boundary between the constant diameter portion 20'M of the outer tube 20 and the reduced diameter portion 20T, and the curvature-changing portion Q21 corresponds to the boundary between the reduced diameter portion 20T and the flat portion along the lamp diameter direction. The curvature-changing portion Q22 is the boundary between the flat portion along the lamp diameter direction and the small diameter portion 21', and the curvature-changing portion Q23 corresponds to the boundary between the reduced diameter portion on the rear end side of the lamp and the cylindrical portion in the small diameter portion 21. The curvature-changing portion Q24 is the boundary between the cylindrical portion and the reduced diameter portion on the front end side of the lamp in the small diameter portion 21', and the bottom portion 21B is the bottom of the recess on the inner surface of the small diameter portion 21'.

When defined in this way, the small diameter portion 21' is expressed as the length along the lamp axis E from the curvature change portion Q22 to the tip tube tip apex 21T (flat portion not included). Along the lamp axis, the tip apex 31T of the inner tube 30 penetrates further toward the lamp tip side (interior) than the curvature change portion Q22 of the small diameter portion 21 to form a fitted state, while the end 41' of the inner electrode 40 is located on the rear end side (toward the center of the discharge vessel) than the curvature change portion Q22 of the small diameter portion 21. In other words, it does not penetrate into the small diameter portion 21'. This makes it possible to prevent insulation breakdown.

The fitting state between the inner tube 30' and the small diameter portion 21' of the discharge vessel 10'T can be realized in various configurations in which the tip portion 31' of the inner tube 30' and the small diameter portion 21' are in contact with each other, and as in the first embodiment, it is not necessary to provide a flat portion or a cylindrical portion. In addition, the inner surface connecting the constant diameter portion 20'M of the outer tube 20' to the small diameter portion 21 via the reduced diameter portion 20'T does not need to have a continuous, smooth curved shape.

For example, a curved surface may not be provided between the curvature-changing portions Q20 and Q21, and the constant inner diameter portion 20'M of the outer tube 20' may be connected to a flat portion; a curved surface may not be provided between the curvature-changing portions Q22 and Q23, and the flat portion may be connected to a cylindrical portion; and a curved surface may not be provided between the curvature-changing portion Q24 and the bottom 21B, and a flat bottom may be used.

The arrangement of the excimer lamp is not limited to the first and second embodiments, and various variations are possible. In this case, a situation may arise where conductors with the same potential as the outer electrodes are arranged in close proximity, but the above-mentioned configuration can prevent dielectric breakdown. The excimer lamp shown in the first embodiment can also be incorporated into an ultraviolet irradiation device, and the excimer lamp shown in the second embodiment can also be incorporated into an ozone generator.

REFERENCE SIGNS LIST 10 Excimer lamp 10T Discharge vessel 20 Outer tube 30 Inner tube 40 Inner electrode 50 Outer electrode 100 Ozone generator

Claims (9)

a discharge vessel having a small diameter portion at its tip;
an inner electrode provided within the discharge vessel;
an inner tube covering the inner electrode;
The tip of the inner tube enters the small diameter portion,
an inner electrode having a tip end positioned along the lamp axis rearward of the small diameter portion; The tip of the inner tube is tapered,
2. The excimer lamp according to claim 1, wherein at least a portion of a side surface of the tip portion is in contact with an inner surface of the small diameter portion. The excimer lamp of claim 2, characterized in that the contact portion of the small diameter portion that contacts at least a portion of the side surface of the tip portion has a curved shape. the small diameter portion has a cylindrical portion protruding toward the outside and/or the inside of the container,
2. The excimer lamp of claim 1, wherein said inner tube is in contact with said cylindrical portion. An excimer lamp according to any one of claims 1 to 4, characterized in that the distance along the lamp axis between the tip of the inner tube and the tip of the inner electrode is greater than the distance along the lamp diameter between the inner electrode and the outer circumferential surface of the inner tube. An excimer lamp according to any one of claims 1 to 5, characterized in that the distance along the lamp axis between the tip of the inner tube and the tip of the inner electrode is longer than the distance along the lamp axis between the tip of the inner tube and the tip of the small diameter portion. The inner tube has a tapered tip,
7. An excimer lamp according to claim 1, wherein the inner electrode is in the form of a foil and is embedded in the inner tube so as to concentrate an electric field therein. An ultraviolet irradiation device comprising the excimer lamp according to any one of claims 1 to 7,
An ultraviolet irradiation device characterized in that the excimer lamp is installed within an apparatus housing with an outer electrode provided on the outer surface of the discharge vessel or a conductor having the same potential as the outer electrode in contact with or in close proximity to the small diameter portion or the end of the discharge vessel. An ozone generator comprising the excimer lamp according to any one of claims 1 to 7,
An ozone generator comprising: a support member that supports the excimer lamp, with the small diameter portion facing an intake fan, at a tip portion of the small diameter portion or an end portion of the discharge vessel, and has the same potential as an outer electrode provided on the outer surface of the discharge vessel .

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