JPS60221945A - Metal vapor electric-discharge lamp - Google Patents

Abstract

PURPOSE:To prevent any deformation of the electrode and any rapid decrease in the output of ultraviolet rays by using a tungsten or a thorium tungsten containing a specific quantity of iron to form the electrode of a metal vapor electric-discharge lamp charged with an iron halide. CONSTITUTION:A pair of facing electrodes 2 and 2 are installed at the ends of a quartz glass tube 1 charged with proper amounts of a starting rare gas, mercury and an iron halide such as iron iodide. Each of the electrodes 2 is prepared by winding an electrode coil 2b holding thoria as an emitter around an electrode axis 2a. Both the electrode axis 2a and the electrode coil 2b are formed by a tungsten containing 100-4,000PPM of iron.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a metal vapor discharge lamp containing at least an iron halide as a metal halide.

[Technical background of the invention and its problems]

Conventionally, metal vapor discharge lamps filled with iron halides, such as iron iodide, have been used in the printing and plate-making industries as ultraviolet light sources because they can provide about twice as much radiant energy in the near-ultraviolet region as high-pressure mercury lamps. Widely used (used mainly in

As the electrode material for this type of discharge lamp, tungsten with a purity of 99.99% or higher, called pure tungsten, or thorium tungsten containing about 0.3 to 5% thoria, etc., is usually used. This method has the disadvantage of causing electrode deformation, resulting in a rapid decrease in ultraviolet output.

The inventors of the present invention investigated and analyzed discharge lamps that had the above-mentioned defects, and found that the iron component of the enclosed iron iodide had disappeared, and that the iron component, which was approximately equivalent to the amount of iron iodide that had been encapsulated, had disappeared from the tip of the deformed electrode to its root. It was found that the concentration gradually changed as it diffused towards the target.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances.

It is an object of the present invention to provide a metal vapor discharge lamp that can prevent deformation of electrodes and rapid decline in ultraviolet output.

[Summary of the invention]

The present invention is characterized in that tungsten or thorium tungsten containing 100 to 4000 PPM of iron is used as an electrode material for a metal vapor discharge lamp containing an iron halide.

[Embodiments of the invention]

The details of the present invention will be explained below with reference to an embodiment shown in the drawings. FIG. 1 shows a front view of a 2 kW metal vapor discharge lamp used as an ultraviolet light source for curing printing ink. In the figure, (1) shows an inner diameter 24 in which an appropriate amount of starting rare gas, mercury, and iron iodide, such as iron iodide, are sealed.
A quartz glass tube with a pair of opposing electrodes (21,
These electrodes (2i, f2i are metal foils (3), (3
) and the external lead-in wires +4'l, +4) are electrically connected to the base (51, (51K) to form a metal vapor discharge lamp.
2a) is wound with an electrode coil (2b) that holds Doria as an emitter, and the material of both the electrode shaft (2a) and the electrode coil (2b) is OO~4000 PP.
It is made of tungsten containing M iron.

When a discharge lamp configured in this way has a rated power of 2 kW and is lit horizontally with AC, it emits light with a spectral energy distribution as shown in Figure 2, and in the wavelength range of 330 to 40'Onm, it emits light that is approximately twice that of a high-pressure mercury lamp. radiant energy was obtained. Next, FIG. 3 shows the life characteristics of this discharge lamp. The vertical axis is the ultraviolet output (%), and the horizontal axis is the lighting time (in hours). 9 Curve A is the above example 9 Curve B is a conventional discharge lamp using pure tungsten as the electrode material. . As is clear from the figure, the effects of the present invention were remarkable, and the deformation of the electrode was, of course, slight.

The ratio of iron to tungsten in the electrode material is 11
If it is less than 00PP, the effect is insufficient.

For example, at 80 to 90 PPM, the result was as shown by curve C in FIG. On the other hand, even if the amount is increased to exceed 4000 PPM, the effect reaches a saturated state and does not go beyond the curve A, and on the contrary, the workability during electrode processing deteriorates rapidly, resulting in an increase in the processing time and yield loss. This is not preferable because it causes disadvantages such as poor performance. Therefore, the ratio of iron to tungsten should be between 100 and 4000 PPM.

In the above embodiments, tungsten containing iron was used as the electrode material, but thorium tungsten may be used instead of tungsten, thorium tungsten may be used for the electrode shaft, tungsten may be used for the electrode coil, or electrode coil may be used instead of tungsten. Even in other configurations such as those that do not use iron, the same effect can be obtained if the electrode material contains the predetermined amount of iron.

Furthermore, the encapsulated metal halide is not limited to iron halide alone, but may also be mixed with other metal halides; in short, all encapsulated iron halides as metal halides have the same effect. is obtained.

〔Effect of the invention〕

As described in detail above, according to the present invention, in a metal vapor discharge lamp containing an iron halide, the electrodes are
Since it is made of tungsten containing 000 PPM of iron or thorium tungsten, it is possible to prevent deformation of the electrode and rapid decrease in ultraviolet output.

[Brief explanation of drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a spectral energy distribution diagram thereof, and FIG. 3 is a comparison diagram of life characteristics of ultraviolet output. (1)・・・・・・Quartz glass tube (2)・・・
... Electrode (2a) ... Electrode shaft (2b) ... Electrode coil agent Patent attorney Noriyuki Chika □Wavelength (nm) Figure 3 □Lighting time (hours)

Claims (1)

[Claims] A pair of opposing electrodes are provided at both ends of a quartz glass tube. A metal vapor discharge lamp in which a starting rare gas, mercury, and at least an iron halide are sealed inside, characterized in that the electrode is made of tungsten or thorium tungsten containing 100 to 4000 PPM of iron. Metal vapor discharge lamp.