JPH0620653A - Sealing part structure of metallic vapor discharge lamp - Google Patents

Abstract

PURPOSE:To hardly cause the leak to the sealing part of a metallic vapor discharge lamp such as a metal halide lamp and the cracking to a sealing glass. CONSTITUTION:A bulb 1 is formed of transparent polycrystal alumina, a cylindrical opening part 2 is formed on the end part, a cap holding through electrode bar 3 is fitted to the cylindrical opening part 2, and the space between the outside of the cap 4 and the opening end of the bulb 1 is sealed by a sealing glass 5 obtained by melting and cooling glass solder. As the glass solder constituting the seal glass 5, a one which mainly contains Al2O3, CaO and SiO2 is used, and the ratios of these components are set so that its thermal expansion coefficient is laid between the thermal expansion coefficient of a W material forming the electrode bar 4 and the thermal expansion coefficient of the transparent alumina forming the bulb 1 at a temperature less than the stable lighting temperature of a metallic vapor discharge lamp (generally, less than 500 deg.C), and the thermal expansion coefficient is larger than that of the transparent alumina at the stable lighting temperature of the metallic vapor discharge lamp.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A mercury lamp utilizing the excitation and emission of mercury in the anode column of a hot cathode arc discharge, a metal halide is evaporated by the heat of a mercury hot cathode arc discharge to dissociate into a metal and a halogen, and a color peculiar to the metal. Conventionally, metal halide lamps that emit light that emits light, or metal vapor discharge lamps that emit yellow-orange light of the D line (589.0nm, 589.9nm) by a hot cathode arc of sodium vapor, such as a sodium vapor discharge lamp, have been conventionally used. Gymnasium and factory lighting, OHP
It is also used as a light source for color LCD projectors and fog lamps for automobiles.

The general structure of the sealing portion of the above metal vapor discharge lamp is such that the amalgam and the like enclosed in the translucent bulb does not leak to the outside so that a cap having an electrode rod penetrating the bulb is attached to the bulb. It is inserted in the opening and this part is sealed with glass solder.

In the past, quartz glass, translucent polycrystalline alumina, or the like was used as the material of the translucent valve, and Nb (niobium) whose coefficient of thermal expansion was almost the same as that of polycrystalline alumina was used as the electrode support rod. ) Is used, so that the same thermal expansion coefficient as those of the glass solder is also used. For example, JP-A-63-136456
According to the publication, Al ₂ O ₃ , CaO, Y ₂ O ₃ and SiO ₂ are mixed at a predetermined ratio, so that the coefficient of thermal expansion is almost equal to that of a glass solder whose coefficient of thermal expansion is slightly smaller than that of alumina. Proposals have been made to prepare glass solder and apply them to the same sealing part.

[0005]

By the way, Nb is expensive and inferior in halogen resistance. Therefore, recently, W-based materials such as W / Th are used as electrode materials. However, the coefficient of thermal expansion of the W-based material is about half that of alumina, and if a glass solder is selected according to the electrode material, corrosion and cracks will occur in the sealing glass.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a bulb of a metal vapor discharge lamp made of translucent alumina, an electrode rod made of a W-based material, and a glass for sealing. The solder contains Al ₂ O ₃ , CaO and SiO ₂ as main components, and the ratio of these components is below the stable lighting temperature of the metal vapor discharge lamp, the coefficient of thermal expansion of which is the coefficient of thermal expansion of the W-based material forming the electrode rod. The coefficient of thermal expansion is between the coefficient of thermal expansion of the translucent alumina that constitutes the bulb and the coefficient of thermal expansion of the translucent alumina at the stable lighting temperature of the metal vapor discharge lamp.

[0007]

Function: At the stable lighting temperature of the metal vapor discharge lamp, compressive stress acts on the sealing glass, and the glass is brittle against tensile stress but exhibits high strength against compressive stress.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a main part of a valve incorporated in an outer cylinder of a metal vapor discharge lamp to which a sealing structure according to the present invention is applied. The bulb 1 is made of translucent polycrystalline alumina, and both ends ( In the figure, only the upper end is shown because of the vertically symmetrical structure), a cylindrical opening 2 is formed, and a cap 4 holding an electrode rod 3 is fitted into the cylindrical opening 2 and the outside of the cap 4 is inserted. The space between the bulb 1 and the open end is sealed with a sealing glass 5 obtained by melting and cooling a glass solder.

A highly corrosive luminescent substance such as amalgam is enclosed in the bulb 1, and the electrode rod 3 is made of a W-based material such as W / Th having excellent resistance to the luminescent substance. Is made of alumina or W-based material.

As the glass solder constituting the sealing glass 5, Al ₂ O ₃ , CaO and SiO ₂ are the main components, and the ratio of these components is below the stable lighting temperature of the metal vapor discharge lamp (usually 500 ° C.). In the following), the coefficient of thermal expansion is between the coefficient of thermal expansion of the W-based material that forms the electrode rod 4 and the coefficient of thermal expansion of the translucent alumina that forms the bulb 1, and at the stable lighting temperature of the metal vapor discharge lamp, The coefficient of thermal expansion was made larger than that of translucent alumina.

In order to satisfy the above-mentioned coefficient of thermal expansion, for example, when the glass solder is composed of only three components of Al ₂ O ₃ , CaO and SiO ₂ , Al ₂ O ₃ is preferably 30 to 45 mol%. , CaO is preferably 45-6.
0 mol% and preferably about 15 mol% or less for SiO ₂ . As a method of improving the wettability of the glass solder to alumina, in addition to the above main components, Y ₂ O ₃ , Bi ₂
Add O ₃ or PbO. However, if a large amount of these is added, the glass transition point and the softening point are lowered, and the durability at high temperature becomes a problem, so the addition ratio of these is 5 mol%.
The following is preferable.

The table below shows the composition of Al ₂ O ₃ , CaO and SiO ₂ .
The experimental results of the relationship between mol% and the coefficient of thermal expansion, glass transition point (Tg) and softening point (Ts) are shown. In the experiment, a predetermined amount of each sample was weighed and an organic solvent such as ethanol was used. By wet mixing, filling in a platinum crucible, and then heating at 1600 to 1650 ° C. in an electric furnace for 30 to 12
A glass is obtained by performing a melting treatment for 0 minutes and then quenching. Then, the obtained glass is cut into a predetermined shape.
The coefficient of thermal expansion and the like of the ground product were measured.

[0013]

[Table 1]

As is clear from the table, Al ₂ O ₃ ; 30
~45mol%, CaO; 45~60mol%, SiO 2; 0~1
As shown in FIG. 2, the glass solder having a composition of 5 mol% has a thermal expansion coefficient almost equal to that of alumina at about 500 ° C., and at a stable discharge temperature (500 ° C. or lower), the thermal expansion coefficient of the W-based material is It is between the expansion coefficient and the thermal expansion coefficient of alumina, and it can be seen that the thermal expansion coefficient becomes larger than that of alumina at the stable lighting temperature (500 to 800 ° C.).

[0015]

As described above, according to the present invention, the glass solder used in the sealing portion of the metal vapor discharge lamp is Al ₂ O.
₃ , CaO and SiO ₂ as main components, and when the ratio of these components is equal to or lower than the stable lighting temperature of the metal vapor discharge lamp, the coefficient of thermal expansion constitutes the valve and the coefficient of thermal expansion of the W-based material constituting the electrode rod. It is between the coefficient of thermal expansion of translucent alumina, and the coefficient of thermal expansion is set to be larger than that of translucent alumina at the stable lighting temperature of the metal vapor discharge lamp. Compressive stress acts on the sealing glass at a stable lighting temperature, and the valve can be reliably sealed.
Halogen vapor does not leak or come into contact with sealing glass and corrode. Further, the glass transition point and the softening point are increased,
Improves durability at high temperature

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a metal vapor discharge lamp to which a sealing structure according to the present invention is applied.

FIG. 2 is a graph showing the relationship between temperature and coefficient of thermal expansion.

[Explanation of symbols]

1 ... Valve, 2 ... Opening part, 3 ... Electrode rod, 4 ... Cap,
5 ... Sealing glass.

Claims (3)

[Claims] 1. A cap, through which an electrode rod penetrates, is attached to an opening of a bulb made of a translucent alumina material, and
In the sealing part structure of a metal vapor discharge lamp in which the opening is sealed with a glass solder, the electrode rod is made of W (tungsten) -based material, and the glass solder is made of Al ₂ O.
₃ , CaO and SiO ₂ as main components, and when the ratio of these components is equal to or lower than the stable lighting temperature of the metal vapor discharge lamp, the coefficient of thermal expansion is the coefficient of thermal expansion of the W-based material forming the electrode rod and the transmittance of forming the bulb. A metal vapor discharge lamp characterized by being located between the thermal expansion coefficients of optical alumina and having a thermal expansion coefficient larger than that of translucent alumina at the stable lighting temperature of the metal vapor discharge lamp. Sealing structure. 2. The glass solder comprises Al ₂ O ₃ of 30.
~ 45mol%, CaO 45 ~ 60mol%, SiO ₂ 15mol
% Or less, The structure of the sealing portion of the metal vapor discharge lamp according to claim 1. 3. The metal vapor discharge lamp according to claim 1, wherein the glass solder contains at least one of Y ₂ O ₃ , Bi ₂ O ₃ and PbO in a proportion of 5 mol% or less. Part structure.