JP2732455B2 - Metal vapor discharge lamp - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metal vapor discharge lamp used for photochemical reactions, curing of paints and inks, and the like.

[Conventional technology and its problems]

Ultraviolet rays are often used to cause a photochemical reaction or to cure paints and inks, but ultraviolet rays having a wavelength range of about 280 to 400 nm are effective for these purposes.

As a source of such ultraviolet rays, a high-pressure mercury lamp filled with mercury and a rare gas in an amount sufficient to maintain arc discharge is placed inside a tube-shaped arc tube having a pair of discharge electrodes opposed to each other at both ends. Metal oxide as a luminescent material,
In many cases, a metal vapor discharge lamp having an increased amount of light emission in an effective wavelength region is used. In particular, a metal vapor discharge lamp in which iron is sealed emits light continuously in a wavelength range of 350 to 400 nm, which is advantageous for purposes such as photochemical reaction and curing of paint.

However, when the metal vapor discharge lamp containing iron is operated for a long time, the iron adheres to the inner wall of the arc tube to form a thin film. For this reason, iron contributing to light emission is reduced, and there is a problem that the formed thin film inhibits the transmission of ultraviolet light and the output of ultraviolet light is reduced. To prevent adhesion to
The UV output is maintained for a long time.

By the way, such a metal vapor discharge lamp may be lit with lower power consumption than rated power depending on its use. In addition, when irradiating an intermittently illuminated object with ultraviolet light, the lighting and turning off cannot be repeated in a short cycle. In order to save power and prevent overheating during non-irradiation, while the shutter is closed, the power consumption is reduced to, for example, about 1/2 of the rated power to maintain lighting. However, in the case where the lamp is lit with power consumption lower than the rated power, as shown in FIG. In the vicinity of the electrodes 2 and 3, the symbol X
As shown by, a phenomenon of locally displacing upward occurs.
Such an arc displacement phenomenon may occur on both of the discharge electrodes 2 and 3 or may occur on only one of the electrodes, and the degree and state thereof vary, but when such arc displacement occurs, The arc tube located immediately above the arc displacement part X is overheated by the approaching arc, devitrifying the quartz glass, and shortening the service life. In addition, when used in combination with a long light-collecting reflector with an elliptical cross section,
Although the arc position and the focal position of the reflecting mirror are made to coincide with each other, since the light of the arc displacing portion X cannot be used outside the focal position of the reflecting mirror, there is a problem that the light use efficiency is reduced.

[Object of the invention]

Accordingly, the present invention provides a metal vapor that, when lit with lower power consumption than the rated power, does not cause displacement of the arc near the discharge electrode, prevents devitrification of the quartz glass, and does not reduce the light use efficiency. An object is to provide a discharge lamp.

[Configuration of the invention and its operation]

According to the configuration of the present invention, an appropriate amount of iron, halogen, and magnesium, together with mercury and a rare gas in an amount sufficient to maintain an arc discharge, are provided inside a tube-shaped arc tube having a pair of discharge electrodes opposed to each other at both ends. In a metal vapor discharge lamp encapsulating, thallium is 3.2 × 10 ^-9
2.02.0 × 10 ^-7 mol.

That is, the inventor has found that thallium (T1) is effective for achieving the above-mentioned object, and has completed the present invention after conducting various experiments. When 3.2 × 10 ^{-9 to} 2.0 × 10 ^-7 mol per CC is filled, the arc is disturbed even when lighting with much lower power consumption than the rated power without affecting the emission spectra of mercury, iron and magnesium. Can be prevented from occurring. Therefore, the quartz glass is prevented from being overheated and devitrified due to the turbulence of the arc, thereby extending the service life. When the arc is used in combination with the light-collecting reflector, the entire arc can be made to coincide with the focal position of the reflector, so that the light use efficiency does not decrease.

In addition, the filling amount of thallium per 1 CC of the inner volume of the arc tube,
If it is less than 3.2 × 10 ^-9 mol, the effect of suppressing arc disturbance is not sufficient, and if it is more than 2.0 × 10 ^-7 mol, mercury,
There is a problem that the output of the emission spectrum of iron and magnesium is weakened, and as a result, the intensity of ultraviolet rays in the effective wavelength range of 280 to 400 nm is reduced.

〔Example〕

 Examples of the present invention will be specifically described below.

The basic structure of the metal vapor discharge lamp targeted by the present invention is the first
As shown in the figure, a pair of electrodes 2 and 3 are opposed to each other at an end inside a tube-shaped arc tube 1 made of a quartz tube having an inner diameter of 22 mmφ, the rated power consumption is 9 KW, and The distance is 750
mm. In the arc tube 1, 285 mg of metallic mercury, 30 mg of mercury iodide, 5.0 mg of iron, 0.7 mg of magnesium,
1.9 mg of thallium iodide and 30 mmHg of xenon gas are sealed. The amount of thallium added and charged is
Is 2.0 × 10 ⁻⁸ mol per 1 CC of the internal volume.

When lighting such a metal vapor discharge lamp at the rated power consumption of 9KW, the lamp current is 10.3A, the lamp voltage is 975V,
Arc 4 is not disturbed. Then, even if the lamp is lit for a long time, no iron adheres to the inner wall of the arc tube 1, and the output of ultraviolet rays is maintained without forming a thin film of iron. In addition, the influence of the addition and encapsulation of thallium on the output of the spectrum of mercury, iron, and magnesium was examined, but the metal vapor discharge lamp of this example has a spectral output of mercury that is lower than that without thallium added. 4% reduction, iron spectral output 4%
And the spectral output of magnesium is reduced by 1%,
The decrease was slight, and the amount added was 1C
At 2.0 × 10 ⁻⁸ mol per C, it was confirmed that thallium had almost no adverse effect on the spectral output of mercury, iron and magnesium. Further, the addition of thallium hardly affects the electric characteristics such as the starting power and the re-ignition voltage.

Next, 20 metal lamps were prepared by changing only the added amount of thallium of the metal vapor discharge lamp, and half of the rated power was produced.
The lamp was turned on at 4.5KW to investigate the turbulence of the arc and the change in the output of ultraviolet light. Table 1 shows the results.

In Table 1, the unit of the added amount of thallium is mol /
CC, x mark of arc disturbance: 18 out of 20 lamps had arc disturbance on both sides, 2 remaining lamps had arc disturbance on one side, and ○ mark: all 20 lamps had no arc disturbance Indicates that
The ultraviolet output indicates a relative value in a wavelength range of 280 to 400 nm.

As can be seen from Table 1, the amount of thallium added was 2.5 × 10
^{At -9} mol / CC, arc disturbance was observed, but 3.0 × 10
Above ^-9 mol / CC, no arc disturbance is observed. On the other hand, as the amount of thallium added increases, the ultraviolet output tends to decrease, but at 2.0 × 10 ⁻⁷ mol / CC, the reduction is 10%, which is sufficiently practical. However, 2.2 × 10 ^-7 mol
In the case of / CC, the decrease was 17%, and the decrease in ultraviolet light was remarkable. After all, the added amount of thallium is 3.2 × 10 ^{-9 to} 2.0 × 10 ^-7 mol / CC
Accordingly, the output of ultraviolet light in the effective wavelength range of 280 to 400 nm is small and practical, and the disturbance of the arc can be completely prevented.

In this embodiment, thallium halide is added, but it may be added as metal thallium, or the same effect can be obtained by mixing and adding both.

〔The invention's effect〕

As described above, the present invention encapsulates thallium in a mercury-iron-magnesium metal vapor discharge lamp in an amount of 3.2 × 10 ^{−9 to} 2.0 × 10 ⁻⁷ mol per 1 CC of the inner volume of the arc tube. Therefore, the added thallium has almost no adverse effect on the output of the emission spectrum of mercury, iron and magnesium, and it is possible to prevent arc disturbance when the lamp is lit with power consumption lower than the rated power. Therefore, it is possible to prevent the quartz glass from being overheated and devitrified, to prolong the service life of the lamp, and to make the entire arc coincide with the focal position of the reflector when used in combination with the light-collecting reflector. Since it is possible, there is an advantage that the light use efficiency does not decrease.

[Brief description of the drawings]

 FIG. 1 is an explanatory view of a metal vapor discharge lamp. 1 ... arc tube, 2,3 ... discharge electrode 4 ... arc

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-48-92871 (JP, A) JP-A-48-92873 (JP, A)

Claims (1)

(57) [Claims] In a tube-shaped arc tube having a pair of discharge electrodes opposed to each other at both ends, an appropriate amount of mercury and a rare gas together with an appropriate amount of iron, halogen and magnesium are added to maintain an arc discharge. In the enclosed metal vapor discharge lamp, thallium is 3.2 × 10 ^{-9 to} 2.0
× 10 ^-7 mol metal vapor discharge lamp.