JP3189481B2 - Dielectric barrier discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a kind of discharge lamp used as, for example, an ultraviolet light source for a photochemical reaction, in which excimer molecules are formed by dielectric barrier discharge and light emitted from the excimer molecules is used. To improve the so-called dielectric barrier discharge lamp.

[0002]

2. Description of the Related Art As a technique related to the present invention, for example, Japanese Patent Application Laid-Open Publication No. 2-7353 discloses a method in which a discharge vessel is filled with a discharge gas for forming excimer molecules, and a dielectric barrier discharge (also known as a dielectric barrier discharge). Ozonizer discharge or silent discharge.
New edition "Discharge Handbook" published by the Institute of Electrical Engineers of Japan, June 2001
A description is given of a radiator for forming excimer molecules by a reprint of the seventh edition of the moon, page 263) and extracting light emitted from the excimer molecules, that is, a dielectric barrier discharge lamp. Also, Japanese Unexamined Patent Publication No. Hei 2-
No. 7353 describes a radiator (for example, a fluorescent lamp) provided with a luminescence (for example, a phosphor) for converting ultraviolet light into light of another wavelength in a discharge vessel of a dielectric barrier discharge lamp. The dielectric barrier discharge lamp as described above is useful because it has various features not found in conventional low-pressure mercury discharge lamps and high-pressure arc discharge lamps. However, the conventional dielectric barrier discharge lamp has a problem that the luminous efficiency is not always sufficient, and that the light output is reduced as the lighting time elapses, that is, the life characteristics are not always sufficient. .

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dielectric barrier discharge lamp having a high luminous efficiency, a light output that does not decrease with the elapse of the lighting time, and a sufficient life characteristic. .

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to fill a discharge vessel with a discharge gas for forming excimer molecules by dielectric barrier discharge, and radiate the excimer molecules generated by the dielectric barrier discharge. This can be achieved by providing a dielectric barrier discharge lamp having a window through which light is extracted, by providing a dielectric thin film on at least a part of the surface of the discharge vessel or the dielectric barrier in contact with the discharge space. The dielectric thin film according to the present invention has a thickness of 50 nm to 1000 nm. Further, the dielectric thin film is made of ZnS, PbF2, CeF3, LaF3.
, BaF2, CaF2, LiF and NaF, the object of the present invention is further achieved. Also, ZnS, PbF2
, CeF3, LaF3, BaF2, CaF2,
The object of the present invention is further achieved by providing at least two kinds of dielectrics selected from LiF and NaF alternately to form a multilayer structure, that is, by forming a multilayer dielectric thin film structure.

[0005] Further, the object of the present invention is further achieved by configuring the dielectric multilayer thin film such that the dielectric multilayer thin film reflects at least 50% of light emitted from the excimer molecule. Further, when the dielectric multilayer thin film is provided, the object of the present invention is further achieved by forming the dielectric thin film in contact with the discharge space with CaF2.

[0006]

We have found that the luminous efficiency of a dielectric barrier discharge lamp is affected by the material of the surface of the dielectric facing the discharge space. That is, a discharge vessel is filled with a discharge gas for forming excimer molecules by a dielectric barrier discharge, and in a dielectric barrier discharge lamp having a window for extracting light emitted from the excimer molecules, a discharge space of the dielectric barrier is provided. Providing a dielectric thin film on at least a part of the contacted surface improved the luminous efficiency of the dielectric barrier discharge lamp by several tens of percent. Although the mechanism of this luminous efficiency improvement is not clear, it seems to be as follows. First, the fact that the characteristics of the dielectric barrier discharge changes depending on the electric resistance of the surface of the dielectric facing the discharge space is described in page 264 of the aforementioned “discharge handbook”.

It is generally considered that a dielectric thin film has a structure composed of a collection of fine crystals or an amorphous substance having a large porosity. Therefore, the dielectric thin film has voids. ing. Therefore, it is considered that the properties of the surface of the dielectric thin film are greatly different from those of the surface of the crystalline or amorphous bulk, and as a result, the properties of the dielectric barrier discharge change and the efficiency is improved.
Further, the dielectric thin film is made of ZnS, PbF2, CeF3.
, LaF3, BaF2, CaF2, LiF and NaF, a greater effect can be obtained.

[0008] In a dielectric barrier discharge lamp having a window filled with a discharge gas for forming excimer molecules by dielectric barrier discharge and extracting light emitted from the excimer molecules, a discharge space of the discharge vessel is provided. ZnS, PbF2, CeF3 on at least part of the facing surface
, LaF3, BaF2, CaF2, LiF and NaF, a dielectric thin film made of at least one of these is provided. These dielectric thin films may be attacked by active atoms and molecules generated by a dielectric barrier discharge. Therefore, the light output does not decrease as the lighting time elapses, and sufficient life characteristics can be obtained. In particular, when the discharge gas contains halogen, a dielectric thin film containing halogen, that is, ZnS, PbF2
CeF3, LaF3, BaF2, CaF2, Li
When a dielectric thin film made of at least one selected from F and NaF is provided, these dielectric thin films are less likely to be attacked by active atoms and molecules generated by a dielectric barrier discharge, and therefore, the lighting time is reduced. The light output does not decrease as time elapses, and sufficient life characteristics can be obtained.

The dielectric thin film is made of ZnS, PbF2, CeF
3, LaF3, BaF2, CaF2, LiF and at least two types of dielectric multilayer films selected from NaF, so that ultraviolet rays or infrared rays generated by dielectric barrier discharge can be reflected and taken out in one direction. Therefore, a long-life and high-efficiency dielectric barrier discharge lamp can be obtained. When manufacturing a dielectric barrier discharge lamp having a multilayer dielectric thin film, only the dielectric thin film in contact with the discharge space comes into contact with air, and the air under the dielectric thin film in contact with the discharge space. Does not come into contact with air. In the multilayer dielectric thin film, when the dielectric thin film in contact with the discharge space is made of CaF 2, the dielectric thin film rarely reacts with moisture in the air and the like, so that a uniform and good quality dielectric barrier is formed. A discharge lamp is obtained.

It has been discovered that dielectric barrier discharge lamps have a significantly lower UV output reduction rate than conventional arc discharge lamps when impurity gases, especially molecular gases such as oxygen, hydrogen, carbon monoxide and water, are present. did. Although this mechanism is not always clear, it is considered as follows.
One of the features of the dielectric barrier discharge lamp is that it can generate ultraviolet light having a wavelength that cannot be obtained by a conventional arc discharge lamp with high efficiency. The generation of the characteristic ultraviolet rays is as follows.
The following mechanism is used. That is, first, high-energy plasma that is not present in the conventional arc discharge lamp is generated by the dielectric barrier discharge. This plasma generates excimer molecules through various collision processes, and the excimer molecules emit characteristic ultraviolet rays. Therefore, the impurity gas present in the discharge space, particularly oxygen, hydrogen, carbon monoxide, molecular gas such as water, not only directly destroys the excimer molecule,
It also acts on the various collision processes to reduce the excimer molecules and thus the UV output. That is, in the dielectric barrier discharge lamp, the ratio of the decrease in the ultraviolet output due to the impurity gas is remarkably large as compared with the conventional arc discharge lamp. It is considered that the dielectric thin film has a structure composed of a collection of fine crystals or an amorphous substance having a large porosity. Therefore, since the dielectric thin film has voids, the impurity gas is impregnated. Is often brought into the discharge vessel.

When a getter is provided in a discharge vessel of a dielectric barrier discharge lamp in which a dielectric thin film is used, oxygen, hydrogen, carbon monoxide, etc. released from the dielectric thin film by the action of discharge plasma or ultraviolet rays as the lighting time elapses. Since impurity gases such as water are removed, a dielectric barrier discharge lamp having excellent life characteristics can be obtained without reducing the density of excimer molecules, and thus without reducing the light output. One of the features of the dielectric barrier discharge lamp is that light having a wavelength that cannot be generated by a conventional arc discharge lamp can be generated with high efficiency. To this end, it is desirable to use a halogen gas as a discharge gas. In this case, it is preferable that the getter disposed in the discharge is made of at least one selected from porous or powdery oxides, nitrides and carbides. The getter is not affected by the halogen gas, and the impure gas is adsorbed by the porous or powdery substance, so that it is possible to obtain a dielectric barrier discharge lamp having excellent life characteristics.

[0012]

[0013]

[0014]

Embodiment In the first embodiment of the present invention, LiF is used as the dielectric thin films 11 and 12 in FIG.
As a discharge gas, a mixed gas of chlorine and xenon is used, and as the getter 6, a getter obtained by compression-molding a mixture of alumina powder and silica powder in a porous state in a ring shape is used. In this embodiment, the wavelength 3
08 nm and ultraviolet rays near it are radiated with high efficiency, and the dielectric is less damaged by chlorine. Moreover, since the porous oxide is used as the getter, the getter is not affected by chlorine in the discharge gas, Therefore, a dielectric barrier discharge lamp having excellent life characteristics was obtained.

[0015]

[0016]

As described above, according to the present invention, it is possible to provide a dielectric barrier discharge lamp having a high efficiency, a light output that does not decrease as the lighting time elapses, and a sufficient life characteristic.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge vessel 2 Inner tube 3 Outer tube 4 Electrode 5 Electrode 6 Getter 11 Dielectric thin film 12 Dielectric thin film 25 Power supply

──────────────────────────────────────────────────続 き Continuation of the front page Examiner Hiroshi Kojima (56) References JP-A-2-7353 (JP, A) JP-A-2-158049 (JP, A) JP-A-2-256153 (JP, A) Japanese Unexamined Patent Publication (Kokai) No. 4-229547 (JP, A) JP-A-6-231173 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 65/00

Claims (5)

(57) [Claims] 1. A dielectric barrier discharge lamp having a window filled with a discharge gas for forming excimer molecules by a dielectric barrier discharge and extracting light emitted from the excimer molecules. A dielectric thin film is provided on at least a part of the surface in contact with the discharge space, and the dielectric thin film is formed of ZnS, PbF2, CeF3, LaF3, and Ba.
A dielectric barrier discharge lamp comprising at least one selected from F2, LiF and NaF. 2. The discharge vessel is energized by a dielectric barrier discharge.
Filling a discharge gas for forming excimer molecules;
Dielectric burrs with windows to extract light emitted from molecules
The discharge space of the dielectric barrier.
A dielectric barrier discharge lamp characterized in that a dielectric thin film is provided on at least a part of the formed surface, and the dielectric thin film in contact with the discharge space is CaF2. 3. The discharge vessel is energized by a dielectric barrier discharge.
Filling a discharge gas for forming excimer molecules;
Dielectric burrs with windows to extract light emitted from molecules
The discharge space of the dielectric barrier.
A dielectric thin film is provided on at least a part of the formed surface , the discharge gas contains halogen, and the thin film is formed of ZnS, PbF2.
, CeF3, LaF3, BaF2, CaF2
, LiF and NaF, comprising at least one selected from the group consisting of LiF and NaF. 4. An electric discharge vessel is subjected to dielectric barrier discharge.
Filling a discharge gas for forming excimer molecules;
Dielectric burrs with windows to extract light emitted from molecules
The discharge space of the dielectric barrier.
A dielectric thin film is provided on at least a part of the formed surface, and the dielectric thin film is formed of ZnS, PbF2, CeF3, LaF3.
, BaF2, CaF2, LiF, and NaF. A dielectric barrier discharge lamp comprising at least two kinds of dielectric multilayer films. 5. A dielectric barrier discharge lamp according to any one of claims 1 to 4 characterized in that a getter the discharge vessel.