JPH01161657A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To suppress blackening of a tube wall so as to improve ultraviolet ray intensity maintenance factor by charging nickel at the specified gram atom number ratio to iron in addition to the iron. CONSTITUTION:Electrodes 2, 2 provided in a light emitting tube 1 are each connected to load wires 5, 5 through metal foils 4, 4 sealed inside the crushed sealing parts 3, 3 of the light emitting tube 1. And rare gas for starting, mercury, iron and halogen are charged into the light emitting tube 1 and nickel of 1/20-1/2 at the gram atom number ratio to the iron is charged. If the nickel is charged additionally into the light emitting tube in advance like this, this nickel reacts on the charged halogen and forms nickel halide and further reacts on the isolated iron and changes it into iron halide. Hereby, tube wall blackening due to adhesion of iron to the tube inside wall is suppressed, and lowering of an ultraviolet ray intensity maintenance factor resulting from the decrease of ultraviolet ray transmissivity by blackening and the decrease of iron being a light emitting metal can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a metal halide lamp used in the field of photochemical reactions such as curing of printing ink using ultraviolet rays.

(Prior art) Metal halide lamps are made by sealing iron and halogen together with a starting rare gas and mercury in the arc tube.

Because it has excellent luminous efficiency in the UV-A region (315 to 400 nm) of 11% in the ultraviolet range, it is often used in place of mercury lamps as a light source for photochemical reactions, such as curing printing ink.

However, this lamp has the drawback that as the lighting time elapses, a black compound is deposited on the inner wall of the arc tube, resulting in an extremely low maintenance rate of ultraviolet light intensity.

To address these drawbacks, for example, Japanese Patent Application Laid-Open No. 57-637
No. 57, Japanese Patent Laid-Open No. 57-101329, etc., disclose means for suppressing the blackening of the tube wall by adding palladium, zirconium, titanium, etc. in addition to iron.

However, for example, when it comes to light sources used as printing ink curing light sources, even the improved lamps mentioned above are not suitable for the recent speed-up of printing presses and the market demand for longer lifespans. He wasn't necessarily in a position to rest.

(Problems to be Solved by the Invention) As mentioned above, in conventional iron-containing metal halide lamps, the maintenance rate of ultraviolet light intensity is extremely reduced due to the blackening of the tube wall, and even in lamps that have been improved in this respect, However, it has not been able to fully meet recent market demands.

Therefore, the present invention solves the above-mentioned conventional drawbacks, and provides a metal halide lamp for photochemical reactions that further suppresses tube wall blackening and has an improved ultraviolet intensity maintenance rate that can fully meet market demands. The purpose is to provide.

[Structure of the invention]

(Means for Solving the Problems) The metal halide lamp of the present invention is configured to further encapsulate nickel in addition to iron in a gram atomic ratio of 1/20 to 1/2 to iron.

(Function) According to the analysis results, the black compound is iron, and it is presumed that the iron sealed in the arc tube as a two-luminescent substance evaporates and adheres to the inner wall of the tube, which appears as a blackening phenomenon. It is not clear why the iron adheres to the inner wall of the pipe, but iron halide produced by the reaction of iron with the encapsulated halogen (including cases where the iron was encapsulated as iron halide from the beginning) evaporates. It is assumed that iron ions dissociate into iron ions and halogen ions in the plasma during discharge, and the liberated iron ions diffuse toward the inner wall of the tube and adhere to the inner wall of the tube before combining with halogen again. .

Therefore, in order to suppress the blackening of the tube wall, that is, the adhesion of iron to the inner wall of the tube, it is sufficient to reduce the iron ions near the inner wall of the tube, and it is necessary to add nickel to the arc tube in advance. For example, this nickel reacts with the encapsulated halogen to form nickel halide, so it may be encapsulated as nickel halide from the beginning. ), this nickel halide reacts with the free iron and converts it into iron halide as shown in the following formula, so it is possible to prevent iron from adhering to the inner wall of the pipe and causing blackening. In addition, one example of the formula is when, for example, iodine is used as the halogen,
Moreover, (g) shows a gas state.

NiI2 (g) +Fe (g) 4 FeC (g)
10Ni (g)Although free nickel Ni is generated in the above reaction formula, Ni has a higher vapor pressure than Fe, so it tends to adhere to the inner wall of the pipe, so it recombines with the halogen. It is believed that blackening can be prevented by repeating the reaction shown in the above formula.

(Example) The present invention will be described in detail below based on an example shown in one drawing. FIG. 1 shows a schematic configuration explanatory diagram of an embodiment of the present invention, in which (1) is a quartz glass arc tube with an inner diameter of 20 groups, and electrodes +2 are placed at both ends of the tube at a distance of 110α. ), (2) are provided. These electrodes (
2) , (21 is the crushing sealing part (3) of 1 arc tube (1)
, (metal foil sealed within 31 (4) , (4)
are connected to the lead wires (5) and (5) through the lead wires (5) and (5), respectively. (61, (6) is a cap made of ceramic, for example, and is used by holding this cap part in a device not shown. Note that 1 arc tube (within 11, for example, argon gas Ar15 as a starting rare gas) - le, mercury Hg 1.2 m
97 cc, /% a iron genide e.g. iron iodide FeI
zO,05In9/cc and a nickel halide such as nickel iodide kNiI20.005 mq/cc are enclosed. Therefore, nickel (Ni) is enclosed in approximately 1/10 of iron (Fe) in terms of gram atomic ratio.

There are three types of lamps: the lamp of the present invention having such a configuration, the previously mentioned conventional lamp filled with only iron (Conventional Example 1), and the conventional lamp filled with palladium, zirconium, or titanium in addition to iron (Conventional Example 2). 2 lamps each
Four lamps were turned on at a rated input of 13.21N, and a comparison test was conducted on the maintenance rate of ultraviolet intensity. The results are shown in FIG. As is clear from the figure, there is no difference in the ultraviolet intensity of each lamp at the initial stage of 1 lighting, but as the lighting time progresses, the difference between the lamp of the present invention and each conventional lamp becomes obvious, and 2
After 000 hours, the maintenance rate of the lamp of the present invention is 90% (
(as an initial value of 100).

It was about 80% in Conventional Example 2, and about 60% in Conventional Example 1.

The amount of nickel enclosed is preferably 1/20 to 1/2 in terms of gram atomic ratio to iron; if the amount of nickel enclosed exceeds this range, the luminous efficiency of ultraviolet rays will decrease;
On the other hand, it was confirmed that if the amount is too small, the tube wall blackening prevention effect decreases.

〔Effect of the invention〕

As detailed above, according to the structure of the present invention, it is possible to suppress the blackening of the tube wall due to adhesion of iron sealed in the tube as a luminescent metal to the inner wall of the tube, thereby reducing the ultraviolet transmittance due to blackening and emitting light. It is possible to obtain a long-life metal halide lamp for photochemical reactions that can sufficiently meet recent market demands by preventing a significant decrease in the maintenance rate of ultraviolet light intensity due to a decrease in iron, which is a metal.

[Brief explanation of the drawing]

FIG. 1 is a schematic structural explanatory diagram of one embodiment of the metal halide lamp of the present invention, and FIG. 2 shows a comparison curve of the ultraviolet intensity maintenance rate between the lamp of the present invention and a conventional lamp. (1)... Arc tube, (2)... Electrode.

Claims (1)

[Claims] In addition to enclosing a starting rare gas, mercury, iron, and halogen in the arc tube, a gram atomic ratio of 1
A metal halide lamp characterized by enclosing 1/20 to 1/2 nickel.