JPH0992202A - Metal halide light emitting tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc tube with improved lamp starting property and heightened lumen maintenance factor by containing further Sc metal in a metal halide arc tube in which an inert gas, mercury, and a metal halide compound are sealed. SOLUTION: In a metal halide arc tube made of quartz and in which a mixture of an inert gas, e.g. Ar, mercury, and metal halide compounds of e.g. Th, Sc, etc., is sealed, Sc metal is further contained in the light emitting tube. The quantity of the metal halide compounds is set to be 0.3-0.9mg/cm<3> and the quantity of Sc metal is preferably set to be 0.9×10<-2> -0.9×10<-1> mg/cm<2> based on the quantity of the Sc halide compound and Sc metal having a regular hexahedron shape with about 0.5mm diameter is used. Consequently, a metal halide arc tube with a long life can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide arc tube, and more particularly, to improve the starting characteristics of a lamp,
The present invention relates to an arc tube for a metal halide lamp having a high luminous flux maintenance factor.

[0002]

2. Description of the Related Art Generally, a metal halide lamp is equipped with a discharge lamp constructed by enclosing a rare gas for starting, mercury and halogen and a metal halide in an arc tube made of quartz. Not only does it have high luminous efficiency, but it also has the advantage of soft light. More specifically, the metal halide lamp, as shown in FIG. 1, is a quartz arc tube 1, an inert gas such as argon (Ar) enclosed in the arc tube, and mercury (Hg).
And a mixture of a metal-halogen compound containing at least one of thorium (Th), sodium (Na), scandium (Sc) and indium (In), and a first discharge is provided at one end of the arc tube. The coil 2a and the first main electrode 2 are installed, and the auxiliary electrode 3 having a needle-shaped tip is installed below the main electrode. At the other end of the above-mentioned discharge tube, another discharge coil 4a is provided.
And the main electrode is installed. A thin metal piece 5 and a lead wire 6 are connected to the main electrodes 2 and 4 and the auxiliary electrode 3, and a bimetal switch 7 is provided between the lead wire 6 to which the first main electrode 2 and the auxiliary electrode 3 are connected. Are connected. Then, one end of the ballast power supply 8 is adapted to be applied to the first main electrode 2, the other end of the ballast power supply 8 is applied to the second main electrode 4, and at the same time, to the auxiliary electrode 3 through the resistor 9. It is configured to be applied.

In the metal halide lamp thus constructed, when the ballast power source 8 is supplied, the ballast power source 8 thus supplied is applied to the first main electrode 2 and the auxiliary electrode 3 and the first main electrode. A glow discharge is generated between the electrode 2 and the auxiliary electrode 3. Due to the heat generated by this glow discharge, the mercury and the metal halogen compound enclosed in the discharge tube 1 are evaporated, and if the temperature inside the arc tube 1 rises above a certain temperature, the bimetal switch 7 is connected. As a result, the glow discharge is transferred to the arc discharge between the main electrodes 2 and 4 to be lit. In metal halide lamps that operate in this way, sodium and scandium as a mixture of metal halide compounds that are enclosed with an inert gas and mercury in the arc tube in order to produce a metal halide lamp with soft light and high efficiency. , Indium iodide, that is, (Na + Sc + Th)
I was mainly added.

[0004]

However, in the metal halide lamp to which iodide is added as described above, the intensity of HgI is increased by the excess iodine, and the starting characteristics are deteriorated. Not only that, Sc iodide easily reacts with SiO ₂ forming the arc tube to damage the arc tube as shown by the following formula (A), or the following formula (B)
Reacts with the water in the arc tube to produce Sc ₂ O ₃ ,
It interferes with the contribution to the luminous efficiency of the lamp. Further, SiI ₄ generated by the following formula (A) reacts in the center of a high vapor pressure arc tube as shown by the following formula (C) to generate Si, and this Si acts as W used for an electrode. It reacts to form a new low melting point alloy and consumes the electrode. At this time, the liberated iodine causes a voltage rise and extinction of the lamp, that is, extinguishes the lamp during lighting, thereby reducing the luminous flux maintenance factor, that is, the life of the lamp.

[0005]

## STR1 ## _{ScI 3 + 3 / 4SiO 2 →} 1 / 2Sc 2 O 3 + 3 / 4SiI 4 (A) 2ScI 3 + 3H 2 O → Sc 2 O 3 + 3H 2 + 3I 2 (B) SiI 4 → Si + 2I 2 (C)

The present invention has been devised to solve the above-mentioned problems of the prior art, and its purpose is to provide a long-life metal halide lamp having excellent starting characteristics and a high luminous flux maintenance rate. It is to provide an arc tube for use.

[0007]

The above objects can be achieved by the inventions described in the respective claims. That is, the metal of the present invention
A characteristic configuration of the halide arc tube is that in the metal halide arc tube in which an inert gas, mercury, and a metal halogen compound are sewn, Sc metal is further included in the arc tube. Thus, by injecting the metal Sc into the arc tube, the reaction between ScI ₃ and the quartz tube (SiO ₂ ) can be suppressed,
Further, the metal Sc reacts with impure gas such as water existing in the arc tube in the initial stage of the product and adsorbs them to suppress the generation of glass iodine, thereby improving the initial characteristics of the product and the luminous flux maintenance factor of the product. be able to. Incidentally, Sc
It is preferable to use a regular hexahedral metal having a diameter of about 0.5 mm. The amount of the metal halogen compound is
It is preferably 0.3 to 0.9 mg / cm ³ . When the amount of the metal halogen compound is less than 0.3 mg / cm ³ , the luminous flux is poor, which is not preferable, and 0.9 mg / cm ³
If it exceeds ³ cm3, unnecessary surplus compounds may remain, which is not preferable. The amount of Sc metal is 0.9 × 10 ^{−2 to} 0.9 × 1 with respect to the amount of Sc halogen compound.
More preferably, it is 0 ^-1 mg / cm ³ . If the amount exceeds this range and the amount is too small, the start-up becomes dull, and if it exceeds the above amount, a reaction with a halogen element such as I occurs to deteriorate the light emission characteristics and the life is shortened, which is not preferable.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an inert gas such as argon and mercury are injected into the arc tube to inject high pressure mercury or the like into the arc tube with a soft light and a metal halogen compound to achieve high efficiency. This is a metal halide lamp to which metal Sc is added in addition to the inert gas, mercury, and metal halogen compound. This metal S
c is the automatic encapsulation machine (DOS) before the arc tube is encapsulated.
(ER machine) or the like and is injected into the arc tube together with other compounds under an inert gas atmosphere such as argon.

[0009]

EXAMPLES Preferred examples and comparative examples of the present invention will be described below. However, in order to facilitate understanding of the present invention, the following example is merely a preferred example of the present invention, and the present invention is not limited to the example described below. (Example 1) A metal halide lamp of 1500 watts, a metal halogen of 22 to 55 mg, an argon gas of 30
A metal halide lamp was manufactured by adding mbar, 17.2 ml of mercury, and 0.5 mg of a regular hexahedron Sc having a diameter of about 0.5 mm.

(Comparative Example 1) A metal halide lamp identical to the above-described example was manufactured except that metal Sc was not added. For the metal halide lamps of the above-mentioned examples and comparative examples, the starting voltage, the restart time,
The luminous flux maintenance factor was measured by the following method, and the results are shown in Table 1.

[0011]

[Table 1] Example 1 Comparative Example 1 ─────────────────────────────── Starting voltage (V) 127 162 162 Restart Voltage (MIN) 8.33 11.1 Luminous flux maintenance factor (%) (500-600 hrs) 87.2 80.5

As shown in Table 1, the metal of the above embodiment
The halide arc tube has a very low starting voltage, a short restart time, and a high luminous flux maintenance rate as compared with the conventional metal halide arc tube manufactured according to the comparative example.

[0013]

As a result of the above, the metal halide lamp using the metal halide arc tube of the present invention has excellent starting characteristics as compared with the conventional metal halide lamp and has a high luminous flux maintenance rate. We were able to provide a long-life metal halide lamp.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the structure of a metal halide lamp.

[Explanation of symbols]

 1 arc tube 2 first main electrode 2a first discharge coil 3 auxiliary electrode 4 second main electrode 4a second discharge coil 5 thin metal piece 6 lead wire 7 bimetal switch 8 ballast power supply 9 resistance

Claims (3)

[Claims] 1. A metal halide arc tube in which an inert gas, mercury, and a metal halogen compound are sealed, wherein the arc tube further contains Sc metal. 2. The amount of the metal halogen compound is 0.
The metal according to claim 1, which is ³ to 0.9 mg / cm ^3.
Halide arc tube. 3. The amount of the Sc metal is 0.9 × 10 ⁻² to 0.9 × 10 ⁻¹ mg / based on the amount of the Sc halogen compound.
The metal halide arc tube according to claim 1 or 2, which has a cm ³ .