JP3116634B2 - 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 an improvement in a so-called dielectric barrier discharge lamp in which excimer molecules are formed by, for example, dielectric barrier discharge, and light emitted from the excimer molecules is used as an ultraviolet light source for photochemical reactions. About.

[0002]

2. Description of the Related Art As a technique related to the present invention, for example, Japanese Unexamined Patent Publication No. 2-7353 discloses that a discharge vessel is filled with a discharge gas for forming excimer molecules, and a dielectric barrier discharge (also called a dielectric barrier discharge). Ozonizer discharge or silent discharge.
New edition published by the Institute of Electrical Engineers of Japan (Discharge Handbook) 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 dielectric barrier discharge lamp as described above has a problem that the light output decreases as the lighting time elapses.

[0003]

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

[0004]

A discharge vessel is filled with a discharge gas for forming excimer molecules by a dielectric barrier discharge, and the discharge gas contains halogen, and the excimer generated by the dielectric barrier discharge is filled. In a dielectric barrier discharge lamp having a window member for extracting light emitted from molecules, at least a part of the window member is made of quartz glass, and the quartz glass contains the same kind of halogen added to a discharge gas. There is.

[0005]

We have found that the cause of the decrease in the optical output of the dielectric barrier discharge is the deterioration of quartz glass as a window member by ultraviolet rays. The dielectric barrier discharge can generate ultraviolet light having a wavelength that cannot be obtained by a conventional arc discharge with high efficiency. For example, a mixed discharge gas of krypton and fluorine
40nm-255nm, 200-2 with krypton and chlorine
Ultraviolet rays in the wavelength range of 300 to 320 nm can be obtained with xenon and chlorine at 40 nm. 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 with high efficiency. When this lamp is turned on for a long time, halogen is taken into quartz glass and the light output decreases. Although the mechanism is not clear, it is considered as follows. The window member and the dielectric are irradiated with such a large amount of ultraviolet rays, a part of the {Si—O—Si} bond on the surface is cut off, and {Si. (• represents an unpaired electron, and Δ represents a bond with oxygen. ), The defects react with the halogen gas, halogen is taken into the quartz glass, the amount of halogen in the discharge space decreases, the amount of excimer generated decreases, and the light output decreases.

[0006] We have made various studies and found that the use of quartz glass obtained by adding the same kind of halogen as the discharge halogen to the quartz glass can suppress the reduction of halogen in the discharge space. This mechanism is not obvious,
Since there is no difference in the concentration of generated defects, the reaction represented by the following reaction formula, that is, the reaction of 2 (≡Si.) + Cl ₂ ⇔2 (≡Si-Cl), moves rightward by adding halogen. It is considered that it is difficult to proceed.

[0007]

1 is a schematic view showing a coaxial cylindrical dielectric barrier discharge lamp according to an embodiment of the present invention. The discharge vessel 1 is one in which the outer diameter D ₁ is the inner tube 2 of 6mm of quartz glass length about 300 mm, an inside diameter D ₂ has a hollow cylindrical shape by arranging the outer tube 3 of 8mm coaxially. The inner tube 2 and the outer tube 3 also serve as a dielectric and discharge window member of the dielectric barrier discharge, and are made of quartz glass containing 500 ppm or more of chlorine by weight. Electrodes 4 and 5 made of a metal net that transmits light are provided on the outer surfaces of the inner tube 2 and the outer tube 3. The discharge space 6 is filled with xenon gas and chlorine as a discharge gas. Thus, when such a dielectric barrier discharge lamp is turned on by the AC power supply 7, a decrease in the density of chlorine-containing excimer molecules is small, and a dielectric barrier discharge lamp with a reduced output of ultraviolet light during use of the lamp is obtained.

[0008]

As described above, the present invention can provide a dielectric barrier discharge lamp with a small decrease in light output by suppressing a decrease in the density of excimer molecules of halogen as the lighting time elapses.

[Brief description of the drawings]

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

[Explanation of symbols]

 2 inner tube 3 outer tube 4,5 electrode 6 discharge space 7 AC power supply

Continuation of the front page (56) References JP-A-2-7353 (JP, A) JP-A-4-229547 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 65 / 00

Claims (2)

(57) [Claims] 1. A discharge vessel filled with a discharge gas for forming excimer molecules by dielectric barrier discharge, and the discharge gas contains a halogen, and has a window member for extracting light emitted from the excimer molecules. In a dielectric barrier discharge lamp, at least a part of a window member is made of quartz glass, and the quartz glass contains the same kind of halogen added to a discharge gas. 2. The dielectric barrier discharge lamp according to claim 1, wherein the halogen is chlorine.