JPH09120795A - Metal vapor discharge lamp and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the lifetime of a metal vapor discharge lamp by preventing the metal substance encapsulated in a light emission tube from reacting with the tube material. SOLUTION: The light emission tube 1 of a metal vapor discharge lamp concerned is made of quartz glass as a light transmitting member and sealed airtightly, and the metal halide NdI is encapsulated in the tube 1 so that electric discharge takes place therein. The inner wall of the tube 1 is lined with a protection film 2 of alumina (Al2 O3 ) as metal oxide which has crystalline property and prevents the metal substance Nd from reacting with the tube material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor discharge lamp and a method for manufacturing the same, and in particular, a halide of a metal substance is enclosed inside the arc tube and a protective film is formed on the inner wall of the arc tube. The present invention relates to a metal vapor discharge lamp and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, as a metal vapor discharge lamp, a mercury lamp in which mercury and a rare gas are enclosed in an arc tube formed of a transparent member such as quartz glass is known. However, this mercury lamp has a poor color rendering property, and in recent years, in order to improve the color rendering property and the luminous efficiency of this mercury lamp, one kind or several kinds of metal halides (metal halides) are enclosed as a light emitting material. Metal halide lamps are becoming popular.

In a metal halide lamp which is such a metal vapor discharge lamp, the enclosed metal halide is dissociated into metal atoms and halogen atoms during lighting, and the metal atoms are excited to emit a spectrum peculiar to the metal. However, since the arc tube becomes hot during lighting, the metal substance dissociated from the enclosed metal halide reacts with the arc tube, causing the arc tube to change color and crystal of the arc tube material. A devitrification phenomenon or the like occurs due to the deterioration, and the light transmittance of the arc tube is lowered. Further, the metal substance of the metal halide is dissolved in the arc tube or disappears by reacting with the arc tube, and the halogen left in the arc tube causes an increase in the starting voltage and the lamp voltage, which may cause the lamp to not light. It causes the phenomenon of disappearing. As a result, the lamp life of the metal halide lamp, which is a metal vapor discharge lamp, is shortened.

The reaction between the metal substance and the arc tube will be described in some detail with reference to the case where the arc tube is made of quartz glass and a rare earth halide is enclosed as a metal halide. While the lamp is on, that is, in the plasma that is being discharged, the rare earth halide is
When halogen is represented by X, it is present by being dissociated into a rare earth metal M and a halogen X as shown in the following formula.

MX → M + X ... The rare earth metal M reacts with quartz glass as shown by the following formula to form a rare earth metal oxide and a composite oxide of SiO ₂ .

M + SiO ₂ → aM ₂ O ₃ · bSiO ₂ + cSIO (a, b, c: coefficient) In addition, SiO produced simultaneously with the above complex oxide in this reaction.
Is unstable, exists as a gas, and recrystallizes as SiO _{2 on} the surface of the arc tube, which is quartz glass. And
The complex oxide and recrystallization appear as a devitrification phenomenon of the arc tube, which lowers the light transmittance of the arc tube and causes a decrease in the luminous flux of the lamp. In addition, since the rare earth metal ions decrease due to the reaction between the rare earth metal and the quartz glass, the amount of free halogen left in the formula increases in the arc tube, which increases the starting voltage and the lamp voltage and causes the deterioration of the life. Of.

Various attempts have been made to solve such problems, and as conventional metal vapor discharge lamps that have made such attempts, for example, JP-A-50-12877 and JP-A-51-51. As disclosed in Japanese Patent No. 32079, a metal vapor discharge lamp in which an inner wall of an arc tube is coated with fine particles of one kind or several kinds of metal oxides to form a protective film, and Japanese Patent Laid-Open No. 50-12881. As disclosed in Japanese Patent Application Laid-Open No. 52-51776, a metal vapor discharge in which a metal alkoxide (metal alcoholate) is coated on the inner wall of an arc tube, thereby forming a protective film of an amorphous metal oxide. Electric lights are known.

[0008]

However, in the conventional metal vapor discharge lamp constructed as described above, although the protective film is formed on the inner wall of the arc tube, it is coated with the fine particles of metal oxide. However, it is difficult to form a dense protective film without defects.Therefore, the enclosed metal substance reacts with the members that make up the arc tube, and the metal substance diffuses into the wall of the arc tube. As a result, the devitrification phenomenon or the like occurs due to the crystallization of the arc tube material, the light transmittance of the arc tube is reduced, and the halogen left in the arc tube causes an increase in the starting voltage and the lamp voltage. There is a problem that the lamp life of the metal vapor discharge lamp is shortened by causing non-lighting or extinguishing phenomenon.

Further, even in the case where a protective film made of an amorphous metal oxide is formed from a metal alkoxide, since the crystal structure is amorphous, it is chemically unstable in a high temperature atmosphere, and a metal substance. It is not possible to sufficiently prevent the reaction between the light emitting tube and the members constituting the arc tube, devitrification phenomenon or the like due to crystallization of the arc tube material is caused, and the light transmittance of the arc tube is reduced, or the halogen left in the arc tube Causes an increase in the starting voltage and the lamp voltage, leading to the phenomenon of non-lighting and extinguishing of the lamp, which shortens the lamp life of the metal vapor discharge lamp.

The present invention has been made in view of the above problems, and an object of the present invention is to release a metal vapor which has a long life and prevents a reaction between the metal substance sealed inside the arc tube and the arc tube. Another purpose is to provide an electric lamp, and another object thereof is to provide a manufacturing method thereof.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an arc tube 1 which is formed of a translucent member and hermetically sealed in the invention of claim 1. In a metal vapor discharge lamp in which a halide of a metal substance is enclosed, and an electric discharge is made inside the arc tube 1, an inner wall of the arc tube 1 has the crystalline metal material and the arc tube 1. The metal oxide protective film 2 is formed to prevent the above reaction.

The invention according to claim 2 is the metal vapor discharge lamp according to claim 1, characterized in that the metal oxide is alumina.

The invention of claim 3 is the method of manufacturing a metal vapor discharge lamp according to claim 1 or 2, wherein the inner wall of the arc tube 1 is coated with a metal alkoxide liquid. The metal alkoxide is fired by raising the firing temperature to a predetermined temperature at which crystallization of the metal oxide occurs so that the protective film 2 of the metal oxide is formed on the inner wall of the arc tube 1. To do.

[0014]

1 and 2 show an embodiment of a metal vapor discharge lamp according to the present invention. This metal vapor discharge lamp is a metal halide lamp having a base 3 at one end. The light emitting tube 1 is held inside the provided outer tube 4 having translucency.

The arc tube 1 is made of a translucent member (here, made of quartz glass) such as quartz glass, high silicate glass, translucent ceramic, etc., and is provided at both ends of a hermetically sealed space. Is provided with an electrode 5, and a halide NdI ₃ of a metal substance, which is a light emitting substance as an encapsulating substance, is provided inside
10 mg, 40 mg of mercury, and 30 torr of Ar gas are enclosed, and a protective film 2 made of alumina, which is a crystalline metal oxide, is formed on the inner wall. The two electrodes 5 are each connected to a lead wire 7 via a molybdenum foil 6, and the lead wire 7 is electrically connected to a base 3 at one end of the outer tube 4 via a support rod 8. In the figure, 9 is an electrode for starting assistance,
Similarly to the support bar 8 via the molybdenum foil 6 and the lead-in wire 7.
It is connected to the.

The metal vapor discharge lamp having such a structure is as follows.
It is manufactured as follows. First, the tubular quartz glass
On the inner surface of the arc tube member, the metal alkoxide liquid Al
(OC _ThreeH₇)_ThreeApply the liquid by dipping coating method,
Let it air dry for 1 hour and then bake at 470 ° C for 1 hour.
Performing Then, it is further continuously
Alumina (Al_TwoO_Three) Causes crystallization at a given temperature
After performing high temperature firing for 30 minutes at a certain temperature of 1250 ° C,
A protective film 2 of alumina, which is a crystalline metal oxide,
Let it form. After that, cut the arc tube member to a specified length
At the same time, the electrodes 5 and the starting assisting electrodes 9 are provided on both ends thereof.
After sealing and exhausting the inside from the exhaust port 10,
The above-mentioned inclusions such as halides of metallic substances
The quality is sealed and sealed to form the arc tube 1. here,
The protective film 2 formed on the inner wall of the arc tube 1 has a thickness of about 0.
It was 5 μm and confirmed to be crystalline by X-ray diffraction.
The peak of alumina was confirmed. And the arc tube 1
In the same way as a conventional metal vapor discharge lamp,
A metal vapor discharge lamp, which is a metal vapor discharge lamp, is held in the outer tube 4
Manufacture Talhalide lamp.

The 250 W type metal halide lamp manufactured in this manner was lit for 6000 hours using a 250 W ballast, and the luminous flux maintenance factor was measured to be 85%. The good result that the starting voltage at that time was 162V was obtained.

On the other hand, similarly, tubular quartz glass
On the inner surface of the arc tube member of Al (OC _ThreeH₇)_ThreeLiquid
Apply by the coating method and let it air dry for 1 hour.
After baking at 470 ° C for 1 hour,
Alumina (Al_TwoO_Three2) formed with the protective film 2
Under the same conditions for 50W type metal halide lamps
Measure the luminous flux maintenance factor after lighting for 6000 hours
And the luminous flux maintenance factor is 65%, and the starting power at that time is
The pressure was a result of 185V. This protective film
2 was confirmed by X-ray diffraction, the protective film 2 was amorphous.
It was confirmed that

The difference between the two results is explained as follows. In other words, comparing the crystalline structure of the protective film 2 with an amorphous (non-crystalline) crystalline structure, the Gibbs free energy, which is a thermodynamic characteristic function, is stable as the value is small. , The reaction occurs in the direction that the Gibbs free energy decreases. This also applies thermally and chemically, and becomes more stable because the atoms are rearranged into a state of lower energy as crystallization progresses. Therefore, by forming the protective film 2 so as to have crystallinity as well, it is possible to obtain a film having excellent heat resistance and chemical resistance as compared with the case of being amorphous.

With the above structure, in the metal vapor discharge lamp according to the present embodiment, since the protective film 2 of crystalline metal oxide is formed on the inner wall of the arc tube 1, thermal, A chemically stable protective film 2 can be formed, and the protective film 2 prevents the reaction between the metal substance dissociated from the enclosed halide of the metal substance and the member constituting the arc tube 1 during lighting. As a result, the devitrification phenomenon of the arc tube 1 does not occur, the decrease in the light transmittance of the arc tube 1 is small, and the dissociated metal substance reacts again with halogen to become a metal halide when light is off. The liberated halogen does not exist in the tube 1, the rise of the starting voltage can be reduced, and the life of the metal halide lamp, which is a metal vapor discharge lamp, can be extended. Furthermore, in the step of baking the protective film 2, the baking temperature is raised to a temperature at which crystallization of the metal oxide occurs, so that the protective film 2 having crystallinity can be easily obtained.

In the above-mentioned embodiment, the protective film 2 is not
Lumina (Al_TwoO_Three) And its film thickness is 0.5μ
An example of a metal vapor discharge lamp with m is given, but the present invention is not limited to this.
Not limited to, the material is titania (TiO 2_Two) Or zirconia
(ZrO_TwoOther metal oxides such as
Is not limited to 0.5 μm. Also, the implementation
In the form of, as a metal substance enclosed in a metal vapor discharge lamp
NdI_ThreeHowever, the present invention is not limited to this.
Encapsulating metal is NaI-TlI-InI or ScI _Three-Na
It may be a halide of another metal substance such as I.
The enclosed amount is not limited to the above embodiment.
In addition, the material of the arc tube, the type and other types of enclosures
Regarding the manufacturing conditions including the amount and firing temperature,
The form is one example, and the present invention is not limited to the embodiment.
It is not limited to what is shown.

[0022]

As described above, according to the present invention, the protective film made of metal oxide having crystallinity is formed on the inner wall of the arc tube. As a result, a thermally and chemically stable protective film can be formed, and by the protective film, the reaction between the metal substance dissociated from the enclosed halide of the metal substance and the member constituting the arc tube in the lighting state. The devitrification phenomenon of the arc tube does not occur, the decrease in the light transmittance of the arc tube is reduced, and the dissociated metal substance reacts with halogen again to become a metal halide when the light is off. As the liberated halogen does not exist in the tube, the rise of the starting voltage can be reduced and the life of the metal vapor discharge lamp can be extended.

According to the third aspect of the present invention, the first aspect is provided.
The protective film of the metal vapor discharge lamp according to claim 2 can be formed by raising the firing temperature to a temperature at which crystallization of the metal oxide occurs in the firing step, and the enclosed metal substance reacts with the arc tube. A metal vapor discharge lamp having a structure that is difficult to manufacture can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a front view showing a main part of an embodiment of a metal vapor discharge lamp of the present invention.

FIG. 2 is a front view showing a partially broken state of the above metal vapor discharge lamp.

[Explanation of symbols]

 1 arc tube 2 protective film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuma Hashimoto 1048 Odakadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Works, Ltd.

Claims (3)

[Claims] 1. A metal vapor discharge lamp in which a halide of a metal substance is enclosed in an arc tube which is formed of a translucent member and which is hermetically sealed, and discharges inside the arc tube. A metal vapor discharge lamp, wherein a protective film of a metal oxide having a crystalline property and preventing a reaction between the metal substance and the arc tube is formed on an inner wall of the arc tube. 2. The metal vapor discharge lamp according to claim 1, wherein the metal oxide is alumina. 3. The method for manufacturing a metal vapor discharge lamp according to claim 1, wherein a metal alkoxide liquid is applied to the inner wall of the arc tube, and the metal alkoxide is baked at a metal oxide. 2. A method for manufacturing a metal vapor discharge lamp, comprising: forming a protective film of the metal oxide on the inner wall of the arc tube by raising the temperature to a predetermined temperature at which crystallization occurs and firing.