JPH11111237A - Dielectric barrier discharge lamp and barrier discharge lamp device - Google Patents

Abstract

(57) Abstract: Provided is a dielectric barrier discharge lamp capable of detecting abnormality of a discharge vessel with a simple configuration, and a dielectric barrier discharge lamp device using the same. When a voltage is applied between a pair of electrodes, dielectric breakdown of a discharge medium occurs in a portion having a second discharge path length,
Creates a spark of discharge. When the discharge is ignited, the discharge subsequently spreads throughout the discharge vessel and the dielectric barrier discharge lamp is turned on. The lamp is usually housed in an outer tube and immersed in water, etc., and lights up.However, if the outer tube breaks and water enters, the surface will be filled with conductors and the impedance will change. Can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dielectric barrier discharge lamp and a dielectric barrier discharge lamp device using the same.

[0002]

2. Description of the Related Art Recently, various dielectric barrier discharge lamps utilizing a dielectric barrier discharge as an ultraviolet light source have been proposed. In this discharge lamp, a discharge medium capable of forming excimer molecules is sealed in a discharge vessel that transmits ultraviolet light, and the wall of the discharge vessel is made of a dielectric material, and one of the electrodes is mesh-shaped. It is arranged and discharges by applying a high voltage between the electrodes.

[0003] Since this discharge is performed through a discharge vessel, its form is a so-called silent discharge, and a discharge current flows in a pulse form. Since this pulsed discharge current involves a high-speed electron flow and has a long rest period, a large amount of the discharge medium is excited, and the excited substance is temporarily coupled to an excimer state. Then, when returning from the excimer state to the ground state, radiation with little reabsorption is emitted with high efficiency. In this multiple discharge, light emission is observed near the intersection of the meshes of the mesh electrodes.

Therefore, the reason why the mesh electrode is used as one electrode in the dielectric barrier discharge lamp is to generate a stable discharge over a large area. Further, the radiation can be guided to the outside through the mesh electrode.

As one example of this type of discharge lamp, Japanese Patent Laid-Open Publication No. Hei 6-310102 discloses a method of stabilizing light output by defining the thickness of conductive wires constituting a mesh and the area of each mesh. A configuration that increases the light extraction efficiency has been proposed. Further, as an embodiment thereof, it is disclosed that a ring-shaped getter is fixed by a projection provided on an outer tube of a discharge vessel.

[0006]

As described above, the dielectric barrier discharge lamp has excellent characteristics. However, since it is a discharge using a discharge vessel as a dielectric, it is necessary to apply a high voltage of several KV. Was. In particular, a higher voltage must be applied, especially for starting.

[0007] Further, depending on the discharge medium to be filled, it is necessary to apply a high voltage of about 1.2 to 1.5 times the rated lighting voltage in order to reliably start, because the impurity gas is easily mixed with the impurity gas. there were.

[0008] In order to detect an abnormality of the lamp, a special circuit is required, and there is a problem that the construction cost is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dielectric barrier discharge lamp and a dielectric barrier discharge lamp using the same, which can detect an abnormality in the discharge vessel with a simple configuration.

[0010]

According to the first aspect of the present invention, there is provided a dielectric barrier discharge lamp comprising: a discharge vessel at least partially radiatively transmissive; and a discharge medium capable of forming excimer molecules enclosed in the discharge vessel. And a pair of electrodes disposed outside the discharge vessel; and detecting means for detecting a change in impedance outside the discharge vessel.

In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

First, the discharge vessel will be described.

The discharge vessel has at least a portion facing the electrode functioning as a dielectric and has airtightness in which a discharge medium is sealed. Furthermore, it is sufficient that at least a part of the radiation generated by the discharge has a function of deriving radiation including a wavelength in a desired wavelength range, and is not limited to a specific material. However, it is generally appropriate to form the discharge vessel from quartz glass.

The discharge vessel is not limited to a specific shape and structure as long as a pair of electrodes can be disposed outside the discharge vessel to generate a dielectric barrier discharge. However, in general, those having a cylindrical shape are practical.

Furthermore, a protective film for the discharge medium may be formed on the inner surface of the discharge vessel. For example, in the case where the component of the discharge medium contains chlorine as described later, forming the MgF2 film can reduce the damage of the discharge vessel due to chlorine.

Furthermore, the discharge medium generates ultraviolet rays by the discharge, but when it is desired to emit visible light, a phosphor layer excited by the ultraviolet rays can be formed on the inner surface side of the discharge vessel. Note that forming the phosphor layer on the inner surface side of the discharge vessel means that the phosphor layer is formed directly on the inner face of the discharge vessel and that the phosphor layer is formed via a protective layer or the like. .

Next, the discharge medium will be described.

The discharge medium is not limited to a specific medium as long as it can form excimer molecules. For example, rare gases such as xenon, argon, and helium, XeCl,
A rare gas halide such as KrCl or ArCl can be used. In the case of a rare gas halide, each of the rare gas and the halogen may be individually enclosed in a discharge vessel.

The electrodes will be described.

When the radiation is led out through the electrode, the electrode on the lead-out side can have a mesh structure. The mesh can be obtained by a wire mesh, a punched metal plate, or the like.

Therefore, if it is not necessary to derive radiation through the electrodes, it need not be a mesh. However, even in such a case, a mesh electrode may be used.

In the second discharge path length portion of the discharge vessel, the electrodes are also provided in this portion. In addition, the protrusion of the discharge vessel in the above-described conventional technique functions only for fixing the getter. Since no electrode is provided on this projection, an effect of improving startability cannot be expected.

The operation of the present invention will be described.

When a voltage is applied between the pair of electrodes, dielectric breakdown of the discharge medium occurs at the portion of the second discharge path length,
Creates a spark of discharge. When the discharge is ignited, the discharge subsequently spreads throughout the discharge vessel and the dielectric barrier discharge lamp is turned on.

The lamp is usually housed in an outer tube and immersed in water or the like for lighting. However, when the outer tube is broken and water enters, the surface is filled with a conductor and the impedance changes. Abnormality can be detected by the detecting means.

In the present invention, since the discharge starts at the second discharge path length of the discharge vessel, the applied voltage can be reduced.

FIG. 1 is a co-author of JMMeek and JDCraggs, John
`` E1ectrlcaI Breakdown of gas '' issued by WI1ey & Sons
es "from Figure 6.10.

In the figure, the horizontal axis represents the horizontal p0d (torr cm) between the gas pressure and the electrode spacing, and the vertical axis represents the breakdown voltage V
S (V) is shown.

FIG. 1 shows that under the condition that the gas pressure is sufficiently high, the breakdown voltage decreases when the distance between the electrodes is reduced even at the same gas pressure. The fact that the present invention holds can be understood from FIG.

The second discharge path length portion has a slightly larger amount of light than the first discharge path length portion, but the second discharge path length portion may be only a part of the whole. Therefore, the influence can be reduced.

In the present invention, since the starting voltage is reduced as described above, the voltage applied at the time of starting can be set to the same value as the voltage applied at the time of stable lighting. However, the present invention allows application of a voltage somewhat higher than the voltage applied during stable lighting. Also in this case, a voltage that is clearly lower than in the past is sufficient.

According to a second aspect of the present invention, there is provided a dielectric barrier discharge lamp according to the first aspect.
The discharge vessel is characterized by comprising an inner tube, an outer tube positioned outside the inner tube with a space therebetween, and a connecting portion connecting both ends of the inner tube and the outer tube.

The discharge vessel has a first discharge path length portion in which a discharge path formed inside contributes to stable lighting, and a second discharge path length portion which contributes at least at startup.
If the second discharge path length is shorter than the first discharge path length, the position, shape, size, and the like are not required to have a specific configuration. Since the portion of the second discharge path length determines the value of the voltage to be applied at the time of starting,
An appropriate discharge path length is set so that a desired voltage can be applied.

According to the present invention, the discharge space of the discharge vessel has a cylindrical shape. This discharge vessel has a compact structure in a dielectric barrier discharge lamp.

The inner tube and the outer tube generally use a cylindrical body, respectively, but the present invention is not limited to this, and a non-cylindrical body such as an elliptic cylindrical body can be used if necessary.

The portion having the second discharge path length can be formed at an arbitrary position in the discharge vessel. For example, it can be formed on the inner tube side or the outer tube side at one axial end of the discharge vessel. The second discharge path length may be formed over the entire length of the discharge vessel in the axial direction.

When one of the pair of batteries is a mesh electrode, the electrode on either side of the inner tube and the outer tube may be a mesh electrode.

According to a third aspect of the present invention, there is provided a dielectric barrier discharge lamp according to the second aspect.
The discharge vessel is characterized in that a portion of the inner tube is enlarged in diameter to form a portion having a second discharge path length.

In the present invention, the portion having the second discharge path length can be formed at any position in the axial direction of the inner tube. For example, it may be any one of the end portion and the intermediate portion in the axial direction.

Further, if necessary, two or more portions having the second discharge path length can be formed. Here, the term “expanded diameter” means that an outer diameter portion of the inner tube on the inner surface side of the discharge vessel is enlarged.

Thus, in the present invention, since the portion having the second discharge path length is formed by enlarging the diameter of a part of the inner tube, the inner tube is relatively easy to form, and the second discharge path length is relatively easy.
It is also easy to dispose electrodes at the discharge path length.

According to a fourth aspect of the present invention, there is provided a dielectric barrier discharge lamp according to the second aspect.
The discharge vessel is characterized in that the inner tube is eccentric with respect to the outer tube to form a second discharge path length portion.

According to the present invention, when forming the discharge vessel, it is only necessary to relatively decenter the inner tube, so that the portion having the second discharge path length can be formed without specially processing the inner tube and the outer tube. It can be easily formed, and the structure of the discharge vessel is simple.

According to a fifth aspect of the present invention, there is provided a dielectric barrier discharge lamp according to the first or second aspect, wherein the discharge vessel has a second discharge path length that is partially depressed. It is characterized by forming a part.

In the present invention, the portion forming the second discharge path length can be arbitrarily large, for example, the minimum.

According to a sixth aspect of the present invention, there is provided a dielectric barrier discharge lamp device according to any one of the first to fifth aspects, and a high-frequency power supply connected to a pair of electrodes of the dielectric barrier discharge lamp. And;

The present invention is a dielectric barrier discharge lamp device having the features and functions of the first to fifth aspects.

[0048]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a longitudinal sectional conceptual view showing a first embodiment of the dielectric barrier discharge lamp and the dielectric barrier discharge lamp device of the present invention.

FIG. 3 is a cross-sectional view of the dielectric barrier discharge lamp.

In each figure, 1 is a dielectric barrier discharge lamp, and 2 is a high frequency power supply.

The dielectric barrier discharge lamp 1 comprises a discharge vessel l
a and a pair of electrodes 1b1 and 1b2.

First, the discharge vessel will be described.

The discharge vessel 1a is made of quartz glass and has a first discharge path length portion 1a1 and a second discharge path length portion 1a2. The portion 1a1 of the first discharge path length is
It comprises an inner tube 1a1, an outer tube 1a0 concentrically arranged at an interval outside the inner tube 1a1, and a connecting portion 1a1 for airtightly connecting the inner tube 1a1 and the outer tube 1a0. The portion 1a2 forming the second discharge path length includes an enlarged diameter portion 1a1 formed at one end of the inner tube 1a1 and an outer tube 1a.
0 and the connecting portion 1a1 that connects the enlarged diameter portion 1a1 and the outer tube 1a0.

The size of the discharge vessel 1a is as follows.

The total length of the discharge vessel 1a is 200 mm,
The outer diameter of a0 is 30 mm, the inner diameter of inner tube 1a1 is 18 mm,
The inner diameter of the enlarged diameter portion 1aL is 22 mm, and the thickness of each of the outer tube 1a0 and the inner tube 1a1 is 1 mm.

Therefore, the portion of the first discharge path length is 1a
1 is 4 mm, and 1a2 of the second discharge path length is 2 mm.

Xenon was sealed in the discharge vessel 1a as a discharge medium at a pressure of 53000 Pa.

Next, the electrodes will be described.

The electrode 1b1 disposed in close contact with the outer surface of the outer tube 1a0 of the discharge vessel 1a is a mesh electrode made of stainless steel.

An electrode 1 disposed in close contact with the outer surface of the inner tube 1a1
b2 is an aluminum plate. The surface of the aluminum plate body facing the discharge vessel 1a is polished and formed into a mirror surface so as to increase the radiation collection efficiency. The electrodes 1b1 and 1b2 are connected to the first vessel 1a of the discharge vessel 1a.
Is disposed not only in the discharge path length portion 1a1 but also in the second discharge path length portion 1a2.

The high frequency power supply will be described.

The high-frequency power supply 2 generates a high-frequency voltage of 40 KHz, and supplies both electrodes 1 b 1,
High frequency power is supplied to 1b2 while performing impedance matching. The detecting means 4 detects that the impedance of the lamp has changed,
Turn off the switch to cut off the power supply.

Finally, the operation will be described.

In order to confirm the operation of the present invention, a dielectric barrier discharge lamp having the above-described structure according to the first embodiment of the present invention and a dielectric for comparison in which an electrode portion facing the enlarged-diameter portion 1a1 is cut away. A barrier discharge lamp was prepared.

The high-frequency power source whose output voltage is variable is connected to both electrodes 1 b 1 and 1 b of the dielectric barrier discharge lamp 1.
b2, the voltage applied to the dielectric barrier discharge lamp 1 was gradually increased, and the dielectric barrier discharge lamp was observed.

As a result, the comparative dielectric barrier discharge lamp was started at 1.8 KV. That is, the starting voltage is 1.8 KV.

On the other hand, the dielectric barrier discharge lamp according to the first embodiment of the present invention was started at 1.33 KV.
That is, the starting voltage was 1.33 KV, which was 74% of the starting voltage of the dielectric barrier discharge lamp for comparison.

Five dielectric barrier discharge lamps having the same structure as those described above were manufactured and measured in the same manner. As a result, the average value was 72%.

FIG. 4 is a longitudinal sectional conceptual view showing a second embodiment of the dielectric barrier discharge lamp and the dielectric barrier discharge lamp device of the present invention.

FIG. 5 is a cross-sectional view of the dielectric barrier discharge lamp.

In each figure, the same parts as those in FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof will be omitted.

This embodiment is different from the first embodiment in the structure of the second discharge path length. That is, the inner pipe 1a1 has a uniform diameter, but is eccentric with respect to the outer pipe 1a0. by this,
A portion 1 having a first discharge path length along the axial direction of the discharge vessel 1a
a1 is on the lower side in the figure, and the second discharge path length portion 1
a2 is also formed on the upper side, respectively.

The size of the discharge vessel 1a is the same as that of the first embodiment except that the diameter of the inner tube 1a1 is uniform at 20 mm over the entire length. The minimum value of the second discharge path length portion 1a2 is 2 mm, and the first discharge path length portion 1a2 is 2 mm.
The maximum value of a2 is 6 mm. First discharge path length part 1
The discharge path length continuously changes from a1 to the second discharge path length portion 1a2.

The starting voltage in the present embodiment is 73% of the starting voltage in the comparative dielectric barrier discharge lamp.
Met.

In the case of the dielectric barrier discharge lamp of the present embodiment, a multi-discharge called a silent discharge frequently occurs on the side of the second discharge path length portion 1a2, and conversely, on the first discharge path length portion 1a1. There is little tendency toward the maximum value side, but there is almost no problem if integration is performed by a reflecting mirror or the like.

FIG. 6 is a vertical sectional conceptual view showing a dielectric barrier discharge lamp and a dielectric barrier discharge lamp device according to a third embodiment of the present invention.

In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

This embodiment is different from the first embodiment in the structure of the second discharge path length. That is, the portion 1a2 of the second discharge path length
Is formed by forming a depression 1aR in a part of the inner tube 1a1.

In each of the above embodiments, an experiment was conducted on the effect on the starting voltage by changing the distance of the second discharge path length portion 1a2 with respect to that of the first discharge path length portion 1al. In the embodiment of FIG.
The ratio was approximately 75% when it became 1/2, and approximately 88% when it became 3/4.

Further, an experiment was conducted on the length of the second discharge path length portion in the axial direction. As a result, it was found that the axial length did not significantly affect the starting voltage, and that 1 mm or more was sufficient. .

[0082]

According to the first to fifth aspects of the present invention, it is possible to provide a dielectric barrier discharge lamp capable of detecting a lamp abnormality with a simple configuration.

According to the second aspect of the present invention, in addition, the discharge vessel is formed by connecting the inner tube and the outer tube located outside the inner tube at an interval by the connecting portion, so that the discharge vessel is compact. A dielectric barrier discharge lamp having a discharge vessel can be provided.

According to the third aspect of the present invention, in addition, a portion of the inner tube is expanded to form a portion having the second discharge path length, so that the portion having the first discharge path length is constant. But the second
The dielectric barrier discharge lamp in which the discharge path length portion is formed can be provided.

According to the fourth aspect of the present invention, since the inner tube is decentered with respect to the outer tube to form the second discharge path length portion, the structure of the discharge vessel is simplified. A barrier discharge lamp can be provided.

According to the fifth aspect of the present invention, in addition, a portion of the second discharge path length is formed by depressing a part of the discharge vessel to form a portion having the second discharge path length. It is possible to provide a dielectric barrier discharge lamp of a minimum size, for example.

According to the invention of claim 6, it is possible to provide a dielectric barrier discharge lamp device having the effects of claims 1 to 5.

[Brief description of the drawings]

[Figure 1] JMMeek and JDCrggs, John Wiley & Sons
Figure 6. E1ectrlcal Breakdown of gases issued by the company
Graph quoted from 10

FIG. 2 is a longitudinal sectional conceptual view showing a first embodiment of a dielectric barrier discharge lamp and a dielectric barrier discharge lamp device of the present invention.

FIG. 3 is a cross-sectional view of the same dielectric barrier discharge lamp.

FIG. 4 is a longitudinal sectional conceptual view showing a second embodiment of the dielectric barrier discharge lamp and the dielectric barrier discharge lamp device of the present invention.

FIG. 5 is a cross-sectional view of the dielectric barrier discharge lamp.

FIG. 6 is a vertical sectional conceptual view showing a third embodiment of the dielectric barrier discharge lamp and the dielectric barrier discharge lamp device of the present invention.

Claims (6)

[Claims] 1. A discharge vessel at least partially radiatively transmissive; a discharge medium capable of forming excimer molecules enclosed in the discharge vessel; a pair of electrodes disposed outside the discharge vessel; Detecting means for detecting a change in impedance of the outer surface of the container; and a dielectric barrier discharge lamp. 2. The discharge vessel according to claim 1, wherein the discharge vessel comprises an inner tube, an outer tube formed at an interval outside the inner tube, and a connecting portion connecting both ends of the inner tube and the outer tube. A dielectric barrier discharge lamp as described. 3. The dielectric barrier discharge lamp according to claim 2, wherein the discharge vessel has a portion whose inner tube is enlarged in diameter to form a portion having a second discharge path length. 4. The dielectric barrier discharge lamp according to claim 2, wherein the discharge vessel forms a second discharge path length portion by eccentricity of the inner tube with respect to the outer tube. . 5. The dielectric barrier discharge lamp according to claim 1, wherein the discharge vessel forms a second discharge path length portion by being partially depressed. 6. The dielectric barrier discharge lamp according to claim 1, an outer tube accommodating the lamp and immersed in a liquid, and impedance matching connected to a pair of electrodes of the lamp. And a high-frequency power source.