JP2775695B2 - 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 so-called dielectric barrier which forms excimer molecules by a dielectric barrier discharge used as an ultraviolet light source for a photochemical reaction and utilizes light emitted from the excimer molecules. It relates to improvement of a discharge lamp.

[0002]

2. Description of the Related Art As a technique related to the present invention, there is, for example, Japanese Patent Laid-Open Publication No. 2-7353, in which a discharge vessel is filled with a discharge gas for forming excimer molecules and a dielectric material is filled. Excimer molecules are formed by barrier discharge (also known as ozonizer discharge or silent discharge; see the revised edition of the “Discharge Handbook” published by the Institute of Electrical Engineers of Japan, reprinted in June 2001, page 263), and the light emitted from the excimer molecules is extracted. A radiator, a dielectric barrier discharge lamp, is described. Japanese Patent Application Laid-Open No. 2-7353 discloses a radiator (for example, a fluorescent lamp) provided with a luminescence (for example, a fluorescent material) for converting ultraviolet light into light of another wavelength in a discharge vessel of a dielectric barrier discharge lamp. Is described. 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 dielectric barrier discharge lamp as described above has a problem that the light output decreases as the lighting time elapses, that is, a problem that the life characteristics are not always sufficient, and the discharge is not necessarily sufficiently stable. There was no problem.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dielectric barrier discharge lamp in which the light output does not decrease as the lighting time elapses, has a sufficient life characteristic, and has a stable discharge.

[0004]

According to a first aspect of the present invention, there is provided a dielectric barrier discharge lamp having a window member for filling a discharge vessel with a discharge gas for forming excimer molecules by dielectric barrier discharge and extracting light emitted from the excimer molecules. This is achieved by providing a getter storage chamber that stores a getter that is electrically connected to the discharge space. Further, the wall member constituting the discharge vessel may be configured so that a part thereof also serves as a part of the wall member constituting the getter accommodating chamber, or the wall member provided independently may be provided. The object of the present invention can be further achieved by a configuration in which the getter accommodating chamber and the discharge space are connected by a tube. Further, the dielectric barrier discharge lamp is evacuated, and a sealing portion for sealing by filling with a discharge gas is
The object of the present invention can be further achieved by providing a structure provided in a part of the getter accommodating chamber.

[0005]

[Function] In the dielectric barrier discharge lamp,
Compared to conventional glow or arc discharge lamps, it was discovered that the presence of impurity gases, especially molecular gases such as oxygen, hydrogen, carbon monoxide, and water, significantly reduced the rate of UV output reduction. 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 efficiently generate ultraviolet light having a wavelength that cannot be obtained with a conventional glow or arc discharge lamp. Generation of the characteristic ultraviolet rays is based on the following mechanism. That is, first, high-energy plasma, which is not found in a conventional glow or 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, impurity gases existing in the discharge space, particularly molecular gases such as oxygen, hydrogen, carbon monoxide, and water, not only directly destroy the excimer molecules, but also act on the various collision processes to cause the excimer molecules. And thus the UV output is reduced. That is,
In the dielectric barrier discharge lamp, the rate of decrease in the ultraviolet output due to the impurity gas is remarkably large as compared with the conventional glow or arc discharge lamp.

When a getter is provided in the discharge space, an impurity gas such as oxygen, hydrogen, carbon monoxide, and water generated from a discharge vessel, a dielectric, an electrode, or the like by the action of discharge plasma or ultraviolet rays as the lighting time elapses is removed. Accordingly, a dielectric barrier discharge lamp having excellent life characteristics can be obtained without a decrease in the density of excimer molecules, and hence a decrease in light output.

In a conventional arc discharge lamp, for example, a solid getter made of an alloy of zirconium and aluminum is fixed to a stem or the like provided in a discharge vessel and is in contact with or in close proximity to discharge plasma. Or a thin film getter made of barium or the like deposited on the tube wall of the discharge vessel in contact with or in close proximity to the discharge plasma. As a result of an experimental investigation by the present inventors, it has been found that in the dielectric barrier discharge lamp, the discharge becomes unstable and the light output becomes unstable in the above-described conventional getter mounting configuration. In other words, in the dielectric barrier discharge lamp, since the discharge voltage is as high as several thousand volts, the discharge is irregularly generated with the conductive getter installed close to the discharge plasma, and the light output becomes unstable. Become. In particular, in a getter having a structure deposited on the tube wall of the discharge vessel, creeping discharge easily occurs between the tube wall of the discharge vessel and the getter, and the rate of occurrence of unstable discharge is extremely large.

[0008] At least a discharge vessel is filled with a discharge gas for forming excimer molecules by dielectric barrier discharge, and a dielectric barrier discharge lamp having a window member for extracting light emitted from the excimer molecules is electrically connected to the discharge space. If a getter housing chamber is provided so that discharge plasma does not directly enter and the getter is housed in the getter housing chamber, irregular discharge occurring between the getter and the getter is eliminated, and the light output is stable. A long-life dielectric barrier discharge lamp is obtained.

Further, when a part of the wall member forming the discharge vessel is also used as a part of the wall member forming the getter accommodating chamber, the lamp is not enlarged, that is, small. The above object can be achieved with the lamp of the above. At this time, by setting the gap L that connects the discharge vessel and the getter accommodating chamber to 20% or less of the discharge gap D, irregular discharge generated between the discharge vessel and the getter is more reliably eliminated, and light A dielectric barrier discharge lamp with a stable output and a long life can be obtained.

Further, when the getter accommodating chamber is formed independently of the discharge vessel and is connected to the discharge vessel by a tube, the influence of the discharge plasma on the getter by changing the thickness and length of the tube. Can be controlled, a more stable discharge can be obtained, and the production is easy. Further, when the dielectric barrier discharge lamp is evacuated to vacuum and a sealing portion for filling and sealing a discharge gas is provided in a part of the getter accommodating chamber, the getter is accommodated in the accommodating chamber through the sealing portion. As a result, there is no need to provide a special part for introducing the getter into the getter accommodating chamber, and therefore, the above-mentioned object can be achieved with a small-sized lamp, and there is an advantage that the manufacture is easy. .

[0011]

FIG. 1 is a schematic view of a coaxial cylindrical dielectric barrier discharge lamp according to a first embodiment of the present invention. Discharge vessel 1
Is a hollow cylindrical shape made of quartz glass having a total length of about 300 mm and an inner tube 2 having an outer diameter of 14 mm and an outer tube 3 having an inner diameter of about 24 mm and a wall thickness of 1 mm. Inner tube 2,
The outer tube 3 also serves as a dielectric barrier for the dielectric barrier discharge and a light extraction window member, and has electrodes 4 and 5 formed of a metal net that transmits light on its outer surface. Therefore, the discharge gap D is 5 mm. At one end of the discharge vessel 1, the tube wall of the discharge vessel 1 is extended to form a disc-shaped partition wall 1.
1 is provided.

An exhaust pipe is provided in the getter accommodating chamber 10, and a metal member having a U-shaped groove having a sectional width of 1 mm and a depth of 1 mm is filled with barium or a barium alloy.
mm barium getter 12 is sealed in the getter accommodating chamber 10 through the exhaust pipe, then the discharge vessel is evacuated, and a discharge gas is sealed, and then sealed with a sealing portion 13 which is a part of the exhaust pipe. Stop. Then, barium getter 1
2 is subjected to high-frequency heating to form a barium thin film 14 on the inner wall of the getter accommodating chamber. The gap L that connects the discharge space 6 and the getter accommodating chamber 10 is set to 0.8 mm,
The discharge space was filled with xenon gas of 300 Torr as a discharge gas, and when the power supply 7 was turned on at an input power of 0.2 Watt per square centimeter of surface area of the dielectric barrier discharge lamp, the electrode 4 formed of a metal mesh was used. , 5,
No discharge was generated between the barium getter 12 and the barium thin film 14, so that a dielectric barrier discharge lamp having a stable light output, a small size, a simple manufacturing method, and excellent life characteristics could be obtained. .

FIG. 2 is a schematic diagram showing a coaxial cylindrical dielectric barrier discharge lamp according to a second embodiment of the present invention. In this embodiment, one end of the inner tube 2 and one end of the outer tube 3 are hermetically sealed by flat discs 21 and 22, respectively.
0 is formed. The disk 21 also serves as the discharge space 6 and the partition wall 11 of the getter accommodating chamber 10. The dielectric barrier discharge lamp having the configuration of the present embodiment has an advantage that the area of the barium thin film 14 can be increased.

FIG. 3 is a schematic diagram showing a coaxial cylindrical dielectric barrier discharge lamp according to a third embodiment of the present invention. At one end of the discharge vessel 1, a hollow disk-shaped getter accommodating chamber 10 is provided with a thin tube 31.
It is provided through. In this embodiment, the electrodes 4 and 5 are changed by changing the inner diameter and length of the thin tube 31.
And the discharge between the barium getter 12 and the barium thin film 14 can be easily suppressed, and therefore, a dielectric barrier discharge lamp having a more stable light output can be obtained.

In a fourth embodiment of the present invention, the barium getter of the second embodiment is made of an alloy of zirconium and aluminum. In this example, no discharge was generated between the electrodes 4 and 5 and the alloy getter of zirconium and aluminum, and thus a dielectric barrier discharge lamp having a stable light output was obtained.

Although all of the above examples are so-called dielectric barrier discharge ultraviolet light emitting lamps having no fluorescent material, the present invention can also be applied to so-called dielectric barrier discharge fluorescent lamps in which a fluorescent material is provided in a discharge vessel. It is obvious. However, when the phosphor is provided in the discharge vessel, since the phosphor is a powder and has a relatively large specific surface area, there is a getter effect by adsorbing an impurity gas on the surface,
The getter effect is not great. That is, the present invention is particularly effective in a dielectric barrier discharge lamp having no powder such as a phosphor in a discharge vessel.

[0017]

As described above, according to the present invention, a dielectric material having a stable discharge characteristic, a stable light output, a light output that does not decrease with the elapse of the lighting time, and a sufficient life characteristic. Barrier discharge lamps can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of a dielectric barrier discharge lamp of the present invention.

FIG. 2 is an explanatory view of another embodiment of the dielectric barrier discharge lamp of the present invention.

FIG. 3 is an explanatory view of another embodiment of the dielectric barrier discharge lamp of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge container 2 Inner tube 3 Outer tube 4, 5 electrode 6 Discharge space 10 Getter storage room 13 Sealing part 14 Barium thin film 31 Thin tube

────────────────────────────────────────────────── ─── Continuation of the front page Examiner Hiroshi Ogawa (56) References JP-A-5-182639 (JP, A) JP-A-3-241656 (JP, A) JP-A-2-7353 (JP, A) JP-A-61-264654 (JP, A) JP-A-59-171448 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 65/00 H01J 61/26

Claims (4)

(57) [Claims] 1. A dielectric barrier discharge lamp having a window member for filling a discharge vessel with a discharge gas for forming excimer molecules by dielectric barrier discharge and extracting light emitted from the excimer molecules. However, a dielectric barrier discharge lamp characterized in that a getter housing chamber into which discharge plasma does not enter is provided, and a getter is arranged in the housing chamber. 2. The device according to claim 1, wherein a part of the wall member forming the discharge vessel also serves as a part of the wall member forming the getter accommodating chamber. Dielectric barrier discharge lamp. 3. The dielectric barrier discharge lamp according to claim 1, wherein the getter housing chamber and the discharge space are connected by a tube. 4. The getter accommodating chamber is provided with a sealing portion for evacuating the dielectric barrier discharge lamp, filling the discharge gas, and sealing the discharge gas.
4. The dielectric barrier discharge lamp according to claim 1.