JP4273380B2 - Metal vapor discharge lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal vapor discharge lamp such as a metal halide lamp using a ceramic arc tube, and more particularly to a metal vapor discharge lamp using a ceramic arc tube whose arc tube end sealing portion is improved by improving the structure of an electrode system. It is about.
[0002]
[Prior art]
As a conventional technique, in Japanese Patent Laid-Open No. 6-196131, as shown in FIG. 7 (sectional view of the main part of the arc tube), a sealing material 33 is provided on the ceramic tubular protruding portion 32 at the end of the discharge vessel 31 of the ceramic arc tube. By using niobium metal having substantially the same thermal expansion coefficient as alumina, which is the material of the ceramic tubular protruding portion, as the current introducing member 34 sealed through the pin, reliability of the sealed portion against stress is ensured.
[0003]
And if niobium metal is exposed inside the arc tube, it will corrode due to contact with the halide enclosed in the arc tube during discharge, so that the niobium metal does not extend inside the arc tube, Further, a structure in which even a halogen-resistant intermediate material 35 such as tungsten or molybdenum is covered with a sealing material 33 is disclosed.
[0004]
[Problems to be solved by the invention]
However, in the case of such a structure, even if the niobium metal is not extended inside the arc tube, if the seal length becomes short, the niobium metal is exposed inside the arc tube, and the halide and niobium are exposed. The problem arises that the metal reacts and corrodes.
[0005]
In addition, if the seal length becomes too long even if it covers with halogen-resistant intermediate materials such as tungsten and molybdenum so that niobium metal is not exposed inside the arc tube, the halogen-resistant intermediate material and the seal material Due to the difference in the coefficient of thermal expansion of the ceramic tubular projecting portion, there arises a problem that a crack occurs in the ceramic tubular projecting portion. Thus, it is difficult to control to the optimum seal length. Even if the seal length can be controlled, when the discharge lamp is turned on for a long time, the halide in the arc tube gradually erodes into the seal material, and the niobium metal may be corroded.
[0006]
The present invention has been made to solve the above-mentioned problems in the conventional ceramic arc tube, and in a metal discharge lamp having a ceramic arc tube having a tubular protruding portion at both ends, at least a cermet conductor is used for the electrode system, and the tubular By sealing between the inner wall surface of the protruding part and the outer peripheral surface of the cermet conductor with a sealing material, the electrode system will not corrode by reacting with the halide in the arc tube regardless of the control of the seal length. It is an object of the present invention to provide a metal vapor discharge lamp having no strong crack structure and having a strong sealing structure.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the invention described in claim 1 is characterized in that the ceramic arc tube has discharge portions of the ceramic discharge tube at both ends of the ceramic discharge tube having an outer diameter smaller than the outer diameter of the discharge portion. In a metal vapor discharge lamp having an ionized discharge substance sealed in an arc tube and having two electrode systems facing each other, the electrode system includes an electrode, a halogen-resistant intermediate material, and a cermet conductor, and the cermet conductor is made of alumina. And molybdenum, the ratio of alumina Al ₂ O ₃ is not less than 30 vol% and not more than 60 vol% , and the remainder is molybdenum, and only a seal material is provided between the inner wall surface of the ceramic tubular protruding portion and the outer peripheral surface of the cermet conductor It is characterized by being sealed with.
[0008]
The invention according to claim 2 is characterized in that the halogen-resistant intermediate material is a tubular metal conductor, a thin metal conductor, a thin metal conductor, a conductor obtained by winding a thin metal conductor around a thin metal conductor, It is composed of any one of conductive ceramics.
[0009]
The invention according to claim 3 is characterized in that the sealing material is not in contact with the halogen-resistant intermediate material, and the invention according to claim 4 is characterized in that the sealing material is an oxide of at least Al, Si, and Dy. The invention according to claim 5 is characterized in that the sealing material contains 5 wt% or less of a halogen-resistant metal in the cermet conductor in addition to the main component oxide. It is characterized by.
[0010]
According to all the inventions of the above claims, regardless of the control of the seal length, the electrode system does not corrode by reacting with the halide in the arc tube, there is no occurrence of cracks in the ceramic tubular protruding portion, and a strong seal A metal vapor discharge lamp using a ceramic arc tube having a structure can be obtained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments will be described. FIG. 1A is a cross-sectional view of a ceramic arc tube according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view of a main part of an end portion of the ceramic arc tube. The ceramic arc tube 1 includes a cylindrical discharge vessel 2 made of translucent alumina, and a ceramic tubular protruding portion 3 disposed at both ends of the discharge vessel 2 via ceramic caps 2a. Yes. An electrode system comprising an electrode 4 having an electrode coil at its tip and a molybdenum rod as a thin rod-shaped metal conductor and a cermet conductor 6 as a halogen-resistant intermediate material 5 is inserted into the hollow portion of the ceramic tubular projection 3. The electrode system is sealed with a sealing material 7. The electrode system is welded with an external lead 8 for current introduction.
[0012]
FIG. 2 is a cross-sectional view of an essential part of an end portion of a ceramic arc tube according to another embodiment of the present invention. An electrode system consisting of an electrode 4 having an electrode coil at the tip and a cermet conductor 6 is inserted and sealed with a sealing material 7. Similarly, external leads 8 for current introduction are welded to the electrode system.
[0013]
As an example of the configuration of the electrode system, an electrode 4 having an electrode coil at the tip as shown in FIG. 3, a molybdenum pipe and a cermet conductor 6 which are tubular metal conductors as a halogen-resistant intermediate material 5, and an electrode as shown in FIG. 4 is a conductor in which a molybdenum wire, which is a thin metal conductor, is wound as a halogen-resistant intermediate material 5 and a cermet conductor 6, and a thin rod-shaped metal conductor, as the electrode 4 and the halogen-resistant intermediate material 5, as shown in FIG. A conductor obtained by winding a molybdenum wire as a thin metal conductor around a molybdenum rod and the cermet conductor 6, or a thin rod-like cermet conductor different from the cermet conductor 6 as the electrode 4 and the halogen-resistant intermediate material 5 as shown in FIG. The cermet conductor 6 may be used. In any case, the space between the inner wall surface of the ceramic tubular protruding portion 3 and the outer peripheral surface of the cermet conductor 6 is sealed with a sealing material 7.
[0014]
Since the cermet conductor 6 is resistant to halogen, it does not corrode by reacting with the halide in the arc tube even if it is exposed in the arc tube. Therefore, the cermet conductor 6 can be extended into the arc tube, and the sealing material 7 does not contact the electrode 4 and the halogen-resistant intermediate material 5 even if the sealing length is increased. Therefore, no matter what material the halogen-resistant intermediate material 5 is in any shape, there is no risk of cracking in the seal portion due to the difference in thermal expansion coefficient with the seal material 7, and control of the seal length is also possible. It becomes easy.
[0015]
At this time, the cermet conductor 6 is exposed to the inside of the ceramic tubular protruding portion 3, but the cermet conductor 6 is formed by sintering with ceramics and a halogen-resistant metal and is made of alumina and molybdenum, for example. It does not corrode by reacting with the halide in the tube. Furthermore, since the cermet conductor 6 is hermetically sintered, the inclusion in the arc tube does not leak from the cermet conductor 6. In addition, since a diffusion layer is formed at the interface between the cermet conductor 6 and the sealing material 7, the sealing is very strong.
[0016]
In the case of a metal halide lamp with a lamp power of 150 W, the dimensions of the discharge vessel 2 are an outer diameter of 11.3 mm, an inner diameter of 9.1 mm, and an overall length of 19 mm, and the narrow tubular protruding end 3 has an outer diameter of 3.3 mm and an inner diameter of 0.98 mm. The length is 14 mm. The electrode system has a length of 10 mm and a diameter of 0.9 mm, which is air-sintered with 50 vol% of alumina and 50 vol% of molybdenum around a tungsten wire 4 and a molybdenum wire diameter of 0.2 mm wound around the same electrode. One end of the cermet conductor 6 is butt welded, and a 0.7 mm molybdenum external lead 8 is butt welded to the other end.
[0017]
The electrode system is inserted 19.5 mm from the end of the narrow tubular projecting portion 3, and the ceramic tubular projecting portion is prepared by melting a sealing material composed mainly of oxides of Al, Si and Dy and containing 3 wt% molybdenum oxide. 3 and the outer peripheral surface of the cermet conductor 6 are sealed. The seal length is 4 to 6 mm, and the cermet conductor 6 is exposed in the narrow tubular protruding portion 3. However, since molybdenum is a halogen-resistant metal, it does not react with the halide and corrode.
[0018]
As for the component ratio of alumina and molybdenum in the cermet conductor 6, when the volume ratio is Al ₂ O ₃ : Mo = 60: 40, a capillary tube is used by using a sealing material composed mainly of oxides of Al, Si, and Dy. The protruding portion 3 and the cermet conductor 6 were sealed with a length of 6 mm. In this sealing process, cracks in the seal portion did not occur, and there was no arc tube leak due to cracks even during lamp operation.
[0019]
In the case where Al ₂ O ₃ : Mo is 30:70 by volume, a ceramic tubular protrusion and cermet are 6 mm in size using a sealing material composed mainly of oxides of Al, Si and Dy and containing 3 wt% molybdenum oxide. The length was sealed. Even in this case, the crack of the seal portion did not occur at the time of sealing and during lamp lighting.
Then, Al ₂ O ₃ in the cermet conductor 6 when 25 vol%, the sealing portion cracks occurred at a rate of about 30% in the sealing process. Further, a cermet conductor containing more than 60 vol% of Al ₂ O ₃ has low conductivity, and is unsuitable as a material for an electrode system as a current introduction body.
[0020]
In addition, when a sealing material containing more than 5 wt% molybdenum oxide is used, the melted portion of the sealing material becomes uneven, and a strong sealing structure cannot be provided. As a result of analysis of the interface between the cermet conductor 6 and the sealing material 7, a diffusion layer of the cermet conductor 6 and the sealing material 7 is formed at the interface, and the sealing is very strong. confirmed. For this reason, the inclusion in the arc tube does not leak from the interface between the cermet conductor 6 and the sealing material 7. The halogen-resistant metal may contain tungsten, rhenium, or the like.
[0021]
【The invention's effect】
As described above, according to the present invention, using a hermetically sintered cermet conductor made of ceramics and a halogen-resistant metal, by sealing the cermet conductor and the ceramic tubular protruding portion with a sealing material, Regardless of the seal length, the electrode system material does not corrode by reacting with the halide in the arc tube, and no cracks occur in the ceramic tubular protrusion, and the metal vapor discharge lamp has a very strong sealing structure. Is obtained.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view of a ceramic arc tube according to an embodiment of the present invention.
(B) It is principal part sectional drawing of the ceramic arc tube edge part of one Example concerning this invention.
FIG. 2 is a cross-sectional view of a main part of an end portion of a ceramic arc tube according to another embodiment of the present invention.
FIG. 3 is a cross-sectional view of a main part of an end portion of a ceramic arc tube according to another embodiment of the present invention.
FIG. 4 is a cross-sectional view of a main part of an end portion of a ceramic arc tube according to another embodiment of the present invention.
FIG. 5 is a cross-sectional view of a main part of an end portion of a ceramic arc tube according to another embodiment of the present invention.
FIG. 6 is a cross-sectional view of a main part of an end portion of a ceramic arc tube according to another embodiment of the present invention.
FIG. 7 is a cross-sectional view of a main part of an end portion of a conventional ceramic arc tube.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ceramic arc tube 2 Discharge vessel 2a Ceramic cap 3 Thin tubular protrusion part 4 Electrode 5 Halogen-resistant intermediate material 6 Cermet conductor 7 Seal material 8 External lead

Claims (5)

Two ends of a ceramic arc tube having a ceramic tubular protrusion having an outer diameter smaller than the outer diameter of the discharge vessel, and an ionized discharge substance sealed in the ceramic arc tube, two opposing electrodes In a metal vapor discharge lamp having a system, the electrode system is composed of an electrode, a halogen-resistant intermediate material, and a cermet conductor, the cermet conductor is composed of alumina and molybdenum, and the ratio of alumina Al ₂ O ₃ is 30 vol. % And 60 vol% or less , the remainder being molybdenum, and only the space between the inner wall surface of the ceramic tubular protruding portion and the outer peripheral surface of the cermet conductor is sealed with a sealing material. The halogen-resistant intermediate material is composed of a tubular metal conductor, a thin metal conductor, a thin rod metal conductor, a conductor obtained by winding a thin metal conductor around a thin rod metal conductor, or a thin rod conductive ceramic. The metal vapor discharge lamp according to claim 1, wherein the metal vapor discharge lamp is provided. The metal vapor discharge lamp according to any one of claims 1 and 2 , wherein the sealing material is not in contact with the halogen-resistant intermediate material . The metal vapor discharge lamp according to any one of claims 1 to 3 , wherein the sealing material is made of at least one of an oxide of Al, Si, and Dy. The sealing material release metal vapors according to any of claims 1 to 4, characterized in that it contains halogen-resistant metal in the cermet conductor in addition to the following 5 wt% of the oxide of the main component Electric light.

Images