JPH07211292A - Sealing part structure for metal vapor arc tube - Google Patents

Abstract

PURPOSE:To prevent the leakage of metal vapor at the time of sealing a metal vapor arc tube or after sealing it. CONSTITUTION:A mixture layer 7, which is composed of Al2O3 and platinum, a platinum layer 8 and a mixture layer 9, which is composed of Al2O3 and platinum, are laminated in order on the surface of an insulating cap 3, and the mixture layer 9 contacts with a sealing glass 4. Furthermore, the insulating glass 3 is formed with a radial hole crossing an internal electrode 5, and a platinum layer 10 is formed in this radial hole, and the internal electrode 5 and an external electrode 6 are electrically connected to each other by the platinum layer 10 and the platinum layer 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for sealing the end portion of an arc tube of a metal vapor discharge lamp such as a metal halide lamp or a sodium lamp.

[0002]

2. Description of the Related Art In a metal vapor discharge lamp such as a metal halide lamp or a sodium lamp, a metal halide or amalgam is put in an arc tube made of translucent alumina, the opening is sealed with an insulating cap, and the cap is attached to this cap. By applying a high voltage between the internal electrodes, an arc discharge is generated between the electrodes, and the metal halide enclosed in the arc tube is evaporated by the heat generated by this arc discharge and dissociates into metal and halogen, resulting in a unique color of the metal. The light is emitted to exhibit.

In order to apply a high voltage to the above-mentioned internal electrodes, conventionally, as disclosed in Japanese Patent Laid-Open No. 3-4438, a through hole is formed in a cap, and a rod-shaped electrode is formed in this through hole. The portion exposed to the inside of the arc tube is used as an internal electrode, and the portion exposed to the outside is used as an external electrode for connecting to a power source.

As described above, when a through hole is formed in the cap and one electrode is inserted into the through hole, there is a disadvantage that the metal halide and the like sealed in the arc tube leaks. Therefore, as disclosed in JP-A-2-132750, internal electrodes and external electrodes are attached to both ends of the cap, and a tungsten film for electrically connecting these internal electrodes and external electrodes is formed on the outer peripheral surface of the cap. In addition, there is one in which the space between the tungsten film and the arc tube opening is sealed with a sealing glass.

[0005]

In the conventional sealing structure in which the tungsten film is formed on the outer peripheral surface of the cap described above, the wettability between the tungsten and the sealing glass is poor, and the sealing is completed before the sealing is completed. Depending on the melting temperature of the glass at the time of adhesion, the metal halide may become a metal vapor and leak, or even after sealing, there is a leak path at the interface between the tungsten and the sealing glass, and after a while, the lamp will There is a problem of disappearing.

[0006]

In order to solve the above-mentioned problems, the first invention of the present application is to mount an internal electrode and to form an insulating cap having a noble metal layer for supplying power to the internal electrode, which is made of a translucent ceramic. Fit into the opening of the arc tube,
In the structure of the sealed portion of the metal vapor arc tube which is sealed with the sealing glass, a mixed layer of the component constituting the arc tube and the noble metal is formed on a portion of the surface of the precious metal layer which is in contact with the sealing glass.

According to the second invention of the present application, an insulating cap having an internal electrode attached thereto and a noble metal layer for supplying power to the internal electrode is fitted into an opening of an arc tube made of a translucent ceramic and sealed. In a structure for sealing a metal vapor arc tube sealed with glass, a mixed layer of a component forming an insulating cap and the noble metal is formed between the noble metal layer and the surface of the insulating cap, and The noble metal layer was formed on the portion excluding the portion in contact with the sealing glass.

According to a third aspect of the present invention, an internal electrode is attached and an insulating cap having a noble metal layer for supplying power to the internal electrode is fitted into the opening of the arc tube made of translucent ceramic and sealed. In the sealing part structure of a metal vapor arc tube sealed with glass, the noble metal layer is composed of a component forming an insulating cap and a mixed component of the noble metal.

[0009]

The sealing glass is not in contact with the noble metal layer but is in contact with the mixed layer of the noble metal and the insulating cap or the components constituting the arc tube, so that the wettability is improved.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a cross-sectional view of the sealing portion structure according to the first invention, and FIG. 2 is an enlarged view of a main part of the sealing portion structure. In FIG. 1, 1 is polycrystalline Al ₂ O having a purity of 99.99% or more. a translucent arc tube made of _3, the arc tube 1 at both ends opening 2 (only opening at one end in the drawing) is formed, Al ₂ in the opening 2
The insulating cap ₃ made of O ₃ is a Dy-Al-Si system or Sr-
It is hermetically sealed via a Ca-Y-Al based sealing glass 4.

An internal electrode 5 made of tungsten is press-fitted into one end surface side of the insulating cap 3, and an external electrode 6 is press-fitted into the other end surface side thereof, and Al ₂ O ₃ and platinum (hereinafter referred to as other (Including a noble metal), a platinum layer 8 and a mixed layer 9 of Al ₂ O ₃ and platinum are sequentially laminated, and a radial hole intersecting with the internal electrode 5 is formed in the insulating cap 3. A platinum layer 10 is also formed in this radial hole, and the platinum layer 10 and the platinum layer 8 electrically connect the internal electrode 5 and the external electrode 6. By forming a mixed layer having the same components as the mixed layer 7 between the platinum layer 10 and the cap 3, peeling of the platinum layer can be prevented as much as possible.

In the mixed layer 7, the mixing ratio (wt%) of Al ₂ O ₃ and platinum is Al ₂ O ₃ : Pt = 1: 1.
0 and the mixing ratio for the mixed layer 9 is Al ₂ O ₃ : Pt.
= 0.5 to 3:10.

Then, the mixed layer 7, the platinum layer 8 and the mixed layer 9 are formed in a thickness of 10 to 20 μm by brushing or the like, and 1
The insulating cap 3 is obtained by firing at 500 to 1650 ° C., the insulating cap 3 is inserted into the opening 2 of the arc tube 1, the sealing glass ring is set, and heated to about 1400 ° C. using a high frequency heating furnace. By doing so, the sealing glass ring is melted and solidified, and the sealing portion structure in which the inside of the opening 2 and the mixed layer 9 are hermetically sealed by the sealing glass 4 is completed.

The mixed layer 7 is an insulating cap 3 and a platinum layer 8.
The platinum layer 8 may be formed directly on the surface of the insulating cap 3 without providing the mixed layer 7. Further, instead of the external electrode 6, power may be supplied to the internal electrode 5 by a connector or the like.

FIG. 3 is a cross-sectional view of the sealing portion structure according to the second invention. The same parts as those in the first invention are designated by the same reference numerals and the description thereof will be omitted. In the second invention, the mixed layer for improving the wettability with the sealing glass is not formed on the outside of the platinum layer 8, and instead the platinum layer 8 is removed from the portion in contact with the sealing glass. By forming the platinum layer 8 only on a part, specifically, on the outer peripheral surface of the large diameter portion of the cap 3, the sealing glass is brought into contact with the mixed layer 7. In the figure, the glass ring 11 is shown as a sealing glass by melting and solidifying. Moreover, in order to make the power supply more reliable, the platinum layer 8
However, the platinum layer 8 may be omitted by supplying power by the mixed layer 7.

FIGS. 4 and 5 are sectional views showing another embodiment of the sealing portion structure according to the second invention. In this embodiment, the insulating cap 3 is rod-shaped. For this reason,
In order to prevent slipping off at the time of sealing, heat treatment is performed by sandwiching a pin 12 made of platinum between the opening 2 and the insulating cap 3 in FIG. Further, in FIG. 5, instead of using the pin 12, a platinum layer or a bottomed cylindrical platinum cap 18 is fitted, and the thickness of the platinum cap 18 prevents the platinum cap 18 from falling off. However, in order to improve the wettability of the glass 11, the lower end portion of the platinum cap 18 has an uneven shape such as a comb tooth shape, and the molten glass 11 is in a structure in which it easily contacts the mixed layer 7.

FIG. 6 is a cross-sectional view of a sealing portion structure according to the third invention. In this sealing portion structure, a step portion 2a is engaged in the opening 2 and an insulating cap 3 is engaged with the step portion 2a. Is formed to prevent the metal from falling off, and the mixed layer 7 composed of a mixed component of the component forming the insulating cap and the noble metal plays a role as a noble metal layer for supplying power to the internal electrode 5.

[0018]

As described above, according to the present invention, the noble metal layer formed on the insulating cap and the sealing glass for sealing the opening of the arc tube are not in direct contact with each other, and the noble metal layer does not contact the noble metal. Since it comes into contact with the insulating cap or the mixed layer with the components that make up the arc tube, the wettability of the sealing glass is improved, and sealing is possible in a short time. Leakage after attachment can be effectively prevented, and the life of the metal vapor arc tube can be significantly extended.

Further, the peeling strength of the noble metal layer can be enhanced by interposing a mixed layer of the component forming the insulating cap and the noble metal between the insulating cap and the noble metal layer.

[Brief description of drawings]

FIG. 1 is a sectional view of a sealing portion structure according to a first invention.

FIG. 2 is an enlarged view of a main part of the same sealing structure.

FIG. 3 is a sectional view of a sealing portion structure according to a second invention.

FIG. 4 is a sectional view showing another embodiment of the sealing portion structure according to the second invention.

FIG. 5 is a sectional view showing another embodiment of the sealing portion structure according to the second invention.

FIG. 6 is a sectional view of a sealing portion structure according to a third invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Arc tube, 2 ... Opening, 3 ... Insulation cap, 4 ... Sealing glass, 5 ... Internal electrode, 6 ... External electrode, 7, 9 ... Mixed layer,
8 ... Platinum (noble metal) layer.

Claims (4)

[Claims] 1. An insulating cap, on which an internal electrode is mounted and a precious metal layer for supplying power to the internal electrode is formed, is fitted into an opening of an arc tube made of translucent ceramic and sealed with a sealing glass. In the sealed part structure of the metal vapor arc tube described above, a mixed layer of a component forming the arc tube and the noble metal is formed in a portion of the surface of the noble metal layer that is in contact with the sealing glass. The structure of the sealing part of the vapor arc tube. 2. The structure for sealing a metal vapor arc tube according to claim 1, wherein a mixed layer of a component constituting the insulating cap and the noble metal is provided between the noble metal layer and the surface of the insulating cap. A sealed structure of a metal vapor arc tube, which is formed. 3. An insulating cap on which an internal electrode is attached and a noble metal layer for supplying power to the internal electrode is formed is fitted into an opening of an arc tube made of translucent ceramic and sealed with a sealing glass. In the sealing part structure of the metal vapor arc tube described above, a mixed layer of the component forming the insulating cap and the precious metal is formed between the precious metal layer and the surface of the insulating cap, and the precious metal layer is sealed. A sealing part structure of a metal vapor arc tube, which is formed in a part excluding a part in contact with glass. 4. An internal electrode is attached and an insulating cap having a noble metal layer for supplying electric power to the internal electrode is fitted into an opening of an arc tube made of translucent ceramic and sealed with a sealing glass. In the sealing part structure of the metal vapor arc tube described above, the noble metal layer is composed of a mixed component of a component forming an insulating cap and the noble metal.