JPH06275234A - Metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To prevent the thin film formation of iron by the action of thallium and uniformly distribute thallium in the tube axial direction when a metal vapor discharge lamp added with iron, thallium, and bismuth is lighted at the load of 25-58W/cm<2> for 1cm<2> on the inner wall of a light emitting tube. CONSTITUTION:A light emitting tube 1 is sealed with mercury, rare gas, iron, halogen, thallium, and bismuth, and it is lighted at the load of 25-58W/cm<2> for 1cm<2> on the inner wall of the light emitting tube 1. The gram atom number ratio (Bi/Tl) between bismuth and thallium is set to 1/8-5/1. The sum of gram quantum numbers of thallium and bismuth is preferably set to 2X10<-8>-2.5X10<-7> for 1cm<3> of volume in the light emitting tube 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a metal vapor discharge lamp used as an ultraviolet ray source.

[0002]

2. Description of the Related Art In the technical fields such as photochemical reaction and curing of paints and inks, ultraviolet rays having a wavelength range of 250 to 400 nm are generally used. A metal vapor discharge lamp is usually used as the ultraviolet ray source. And 350-400
Encapsulating iron with a large number of emission line spectra in the wavelength range of nm is more convenient for the above applications. But,
When a metal vapor discharge lamp containing iron is lit for a long time,
Iron adheres to the inner wall of the arc tube to form a thin film. For this reason, the amount of iron that contributes to light emission is reduced, and the formed thin film impedes the transmission of ultraviolet rays, and the output of ultraviolet rays is also reduced. In order to improve this problem, it is known to add thallium to a metal vapor discharge lamp containing iron.

A conventional metal vapor discharge lamp containing thallium has a load of 25 W / c per cm ^{2 of the} inner wall of the arc tube.
It was used below m ² . However, recently, there has been a demand for stronger UV intensity output, and the load must be 25
The lamp is lit while cooling the arc tube to a level of 58 W / cm ² over W / cm ² . (The arc tube temperature must always be maintained within an appropriate range, and if the load per cm ^{2 of} the arc tube inner wall exceeds 58 W / cm ² , the temperature rise cannot be substantially suppressed only by cooling.) When turned on, the action of thallium can maintain the prevention of the iron thin film, but strong cooling of the arc tube causes thallium to condense near both electrodes. As a result, it was found that the emission of thallium was stronger near both electrodes of the arc tube than in the central part of the arc tube, and therefore the ultraviolet intensity distribution in the axial direction of the arc tube was not uniform.

Thallium has a strong emission line spectrum in the effective ultraviolet wavelength range of 352 and 378 nm, and when the emission intensity of thallium increases, the emission intensity of mercury tends to decrease accordingly. Therefore, if thallium is unevenly distributed in the tube axis direction, the ultraviolet ray output is also unevenly distributed in the tube axis direction. This is very inconvenient when using such a lamp as a UV source.

[0005]

The problem to be solved by the present invention is to provide a metal vapor discharge lamp containing thallium with a load of 25 W / cm ² per cm ^{2 of the} inner wall of the arc tube.
When the lamp is turned on at a rate of 58 W / cm ² or less, the thin film of iron can be effectively prevented by the action of thallium, and the thallium is unevenly distributed in the lamp axial direction. To prevent.

[0006]

A metal vapor discharge lamp according to the present invention is characterized in that mercury, a rare gas, and
Thallium and bismuth are enclosed together with iron and halogen, and the load per cm ^{2 of the} inner wall of the arc tube is 25 W / c
A metal discharge lamp lit at 58 W / cm ² or less over m ² , wherein the gram atom number ratio Bi / Tl of bismuth to thallium is 1/8 to 5/1.
Is characterized in that. More preferably, the sum of the number of gram atoms of thallium and bismuth in the inclusion is 2 × 10 ^{−8 to} 2.5 × 10 ⁻⁷ per cm ^{3 of the} inner volume of the arc tube.

[0007]

[Function] Since the enclosed amount of bismuth is within a specific range with respect to thallium, even if the load per 1 cm ^{2 of the} inner wall of the arc tube exceeds 25 W / cm ² and is turned on at 58 W / cm ² or less, the thallium causes It is possible to effectively prevent the formation of the iron thin film and prevent the non-uniform distribution of thallium in the tube axis direction. Therefore, a uniform and stable ultraviolet ray output can be obtained in the tube axis direction of the lamp.

At this time, the sum of the number of gram atoms of thallium and bismuth is 2 × 10 ^-8 per 1 cm ^{3 of the} inner volume of the arc tube.
It is desirable to set it to ˜2.5 × 10 ⁻⁷ . The reason for this is that if the sum of the number of gram atoms of thallium and bismuth is less than this range, the effect of thallium on preventing the thin film of iron is small, and if it is more than this range, there is a problem of impeding the spectral intensity of iron. .

[0009]

1 shows the basic construction of a metal vapor discharge lamp according to the present invention. This metal vapor discharge lamp (hereinafter, also referred to as a lamp) is an arc tube 1 made of quartz glass.
A pair of electrodes 2 are arranged so as to oppose each other in the tube axis direction at both ends of the inside, and the electrodes 2 and the external leads are interposed via the metal foil 3 made of molybdenum sealed in the seal portions 11 at both ends of the arc tube 1. And 4 are electrically connected. For example, this lamp has an inner diameter of 22 mm, a distance between electrodes of 250 mm, and a rated power consumption of 7 KW. And as an enclosure, 260 mg of metal mercury, 9.1 mg of mercury iodide, and iron 1.
3 mg, thallium iodide 1.2 mg, bismuth iodide 2.9
mg, xenon gas 2.13 × 10 ⁴ Pa (160 to
rr). In the fill according to this example, the ratio of bismuth to thallium in grams is 4 /.
3 and the load per cm ^{2 of the} inner wall of the arc tube is 41 W / cm
² , and the sum of the number of gram atoms of thallium and bismuth per cm ^{3 of the} inner volume of the arc tube is 8.5 × 10 ⁻⁸ .

FIG. 2 shows the distribution of the sum of the intensities of the 352, 378 nm emission line spectrum of thallium in the direction of the lamp tube axis. In the figure, the curve a shows the value in the lamp having the above configuration. On the other hand, with the same configuration as the above lamp, except for bismuth iodide from the filling material,
A metal vapor discharge lamp in which bismuth was not enclosed was made for comparison. And when I turned it on in the same way,
It was found that thallium aggregated in the vicinity of both electrodes, and the spectrum intensity of thallium in the tube axis direction was unevenly distributed as shown by the curve b in FIG.

As described above, it has been found that by enclosing bismuth together with thallium in the arc tube, it is possible to prevent the non-uniform distribution of thallium in the tube axis direction. Therefore, in order to obtain a more effective encapsulation amount of bismuth, Experiments were carried out by changing the encapsulation amount of. FIG. 3 shows the emission lines of thallium 352 and 378 in the tube axis direction of the arc tube when the lamp was made with the same configuration and lit under the same conditions except that only the amount of bismuth enclosed was changed. The distribution of the sum of the spectrum intensities is shown. Furthermore, in order to show the degree of non-uniformity, the ratio of the minimum value to the maximum value of the sum of the emission line spectrum intensities of thallium 352 and 378 in the tube axis direction was determined.

From the figure, if the gram atom number ratio of bismuth to thallium is ⅛ or more, the emission intensity distribution of thallium is uniform throughout, but by increasing the amount of bismuth, the gram atom number ratio to thallium is 5%. It has been found that when encapsulating beyond / 1, the damage to the electrode becomes extremely severe and a new defect occurs. Therefore, the gram atom number ratio Bi / Tl of bismuth to thallium is 1/8.
Within a specific range of up to 5/1, the effect of preventing thin film of iron by thallium and the wear of electrodes are not adversely affected, and the load per 1 cm ^{2 of the} inner wall of the arc tube is 25 W / cm.
It is also lit ² beyond at 58W / cm ² or less can prevent the uneven distribution in the tube axis direction of the thallium. On the other hand, the ratio of the number of gram atoms to the thallium of bismuth Bi /
If Tl is less than 1/8, the uneven distribution of thallium in the tube axis direction cannot be prevented, and if it exceeds 5/1, a new problem of electrode wear occurs.

In this embodiment, metallic iron, thallium halide and bismuth halide were added, but they may be added as iron halide, thallium metal and bismuth metal, or as a mixture thereof. The same effect is obtained. In addition to xenon, the rare gas may be argon, krypton, neon, or the like alone or in 2
You may mix 1 or more types.

[0014]

EFFECTS OF THE INVENTION With this structure, the amount of bismuth enclosed is within a specific range with respect to thallium, so that the load per 1 cm ^{2 of the} inner wall of the arc tube exceeds 25 W / cm ^2.
Even if the lamp is turned on at 8 W / cm ² or less, the thin film of iron can be effectively prevented from being formed by thallium, and the uneven distribution of thallium in the tube axis direction can be prevented. More preferably, the sum of the number of gram atoms of thallium and bismuth is 2 × 10 ^{−8 to} 2.5 × 1 per 1 cm ^{3 of the} inner volume of the arc tube.
By defining ^0-7 , it is possible to significantly prevent the formation of an iron thin film, while at the same time, it is possible to sufficiently extract the spectral intensity of iron. Therefore, a uniform and stable ultraviolet ray output can be obtained in the tube axis direction of the lamp.

[Brief description of drawings]

FIG. 1 shows a metal vapor discharge lamp according to the present invention.

FIG. 2 shows the emission spectrum intensity of thallium in the tube axis direction of the arc tube.

FIG. 3 shows the amount of bismuth enclosed and the distribution of thallium in the tube axis direction.

[Explanation of symbols]

 1 arc tube 2 electrode 3 metal foil 4 external lead

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Okamoto 1194 Sado, Bessho-cho, Himeji-shi, Hyogo Ushio Denki Co., Ltd. (72) Kazuyuki Mori 1194 Sasato, Bessho-cho, Himeji-shi, Hyogo Ushio Electric Co. In-house (72) Inventor Masayoshi Oyama 1194 Sado, Bessho-cho, Himeji-shi, Hyogo Ushio Electric Co., Ltd.

Claims (2)

[Claims] 1. An arc tube is filled with thallium and bismuth together with mercury, a rare gas, iron, halogen, and a load of 25 W / cm per 1 cm ^{2 of the} inner wall of the arc tube.
A metal vapor discharge lamp is lit up with 58W / cm ² or less beyond ^2, of the enclosure, the number of gram atom ratio thallium bismuth Bi / Tl is 1 / 8-5 / 1 Characteristic metal vapor discharge lamp. 2. The sum of the number of gram atoms of thallium and bismuth in the filling material is 2 × 10 per 1 cm ^{3 of the} inner volume of the arc tube.
^{-8 to} 2.5 × 10 ^-7 , The metal vapor discharge lamp according to claim 1, wherein