JPH079792B2 - Metal vapor discharge lamp - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metal vapor discharge using an arc tube in which both ends of a translucent ceramic tube are hermetically sealed with a closing body and a metal or a metal compound is sealed inside. It is about electric lights.

2. Description of the Related Art A high-pressure sodium lamp utilizing a sodium vapor discharge using a translucent ceramic tube as an envelope of an arc tube is well known as a lamp having excellent luminous efficiency and life characteristics. Also, using a transparent quartz glass tube as the envelope of the arc tube,
Metal halide lamps containing metal halides
Although the luminous efficiency is inferior to the high pressure sodium lamp,
Widely used as a high color rendering lamp mainly for interior lighting. However, these high-pressure sodium lamps and metal halide lamps have their own advantages and disadvantages, and do not have satisfactory performance. Therefore, recently, a metal halide lamp has been attempted in which a translucent ceramic tube used in a high-pressure sodium lamp as an arc tube is used as an envelope and a metal halide is enclosed inside. The translucent ceramic has excellent heat resistance and halogen resistance as compared with quartz glass, and therefore can increase the vapor pressure of the metal halide in the arc tube and improve the luminous efficiency and life characteristics. However, the translucent ceramic tube cannot be crushed and sealed by heating and softening like a quartz glass tube. Therefore, the arc tube end blocker is used, and the blocker and the translucent ceramic tube are sealed. The material is airtightly sealed by brazing with a material. Further, as the blocker, a conductive ceramic having excellent halogen resistance and a coefficient of expansion substantially matching that of a translucent ceramic tube, or a molded product having a conductive metal film sandwiched inside the ceramic is conventionally used.

Problems to be Solved by the Invention However, using such a translucent ceramic tube,
In metal vapor discharge lamps with metal halides sealed inside, simply use a sealing material containing Al ₂ O ₃・ CaO or Al ₂ O ₃・ MgO as the main component, which has been used in conventional high pressure sodium lamps. When applied, it is excellent in airtightness, but inferior in halogen resistance, metal halides are consumed during lamp lighting, the lamp characteristics are greatly changed, and it cannot be used.
Therefore, as a sealing material with excellent halogen resistance, a study was conducted on materials containing rare earth oxides such as Al ₂ O ₃ , SiO ₂ and Y ₂ O ₃ , La ₂ O ₃ as the main components, with different composition ratios. But has a melting point
It has a proper value of 1300 to 1500 ℃, and the more excellent the halogen resistance is, the more the coefficient of thermal expansion tends to be far from that of the translucent ceramic tube and the closing body. There is a problem that the brazed portion between the photoceramic tube and the closing body may leak early.

Means for Solving the Problems The present invention relates to a metal vapor discharge lamp using an arc tube in which both ends of a translucent ceramic tube are hermetically sealed with a closing body, and a metal or a metal compound is sealed inside, Between the translucent ceramic tube and the closing body, a sealing material with excellent corrosion resistance against the inside of the arc tube is used on the inner surface side of the arc tube, and a sealing material with excellent airtightness is used on the outer surface side of the arc tube. By brazing,
It is intended to provide a metal vapor discharge lamp having excellent reliability and lamp characteristics, particularly a metal halide lamp in which a metal halide is enclosed in an arc tube.

Examples Hereinafter, details of the present invention will be described with reference to the illustrated examples.

FIG. 1 is a sectional view showing an embodiment of an arc tube of a 250 watt metal halide lamp according to the present invention, and FIG. 2 is an enlarged sectional view of one end of the arc tube of FIG. Figure 1,
In FIG. 2, a semi-closed type inner diameter made of a translucent alumina ceramic tube, and ring-shaped alumina ceramic members made of the same material are integrally molded at both ends.
16mm, 50mm long arc tube bulb 1 with electrodes 2,
2'and external lead wires 3,3 'are attached to the closing body 4,
4'is hermetically brazed and sealed by sealing materials 5, 5'and 6, 6 '. The closures 4 and 4'are formed by integrally sintering a conductive metal film 7 between alumina ceramic sheets to provide airtight and conductive functions. The sealing material 5, 5'on the inner surface side of the arc tube is mainly composed of rare earth oxides such as Al ₂ O ₃・ SiO ₂ and La ₂ O ₃ , Y ₂ O ₃ and has excellent halogen resistance. However, since the content of SiO ₂ is high, the coefficient of thermal expansion is smaller than that of alumina ceramics. Also, the sealing material on the outer surface of the arc tube
6,6 ′ is mainly composed of Al ₂ O ₃ · CaO · Y ₂ O ₃ and has a coefficient of thermal expansion well matched to that of alumina ceramic. The arc tube vibe 1 is filled with mercury and metal halides such as sodium iodide and scandium iodide, and argon gas (not shown) as a starting rare gas.

The brazing of the end portion of the arc tube as described above is performed by using the ring-shaped sealing materials 5 and 5 ′ on the inside and the sealing materials 6 and 6 ′ on the outside, and the arc tube bulb 1 and the closing body 4. , 4 ', and by heating and melting at a temperature of about 1300 to 1500 ° C at the same time in vacuum or in an atmosphere of an inert gas such as argon. In this case, in order to further improve the halogen resistance and the airtightness, the melting layer of the sealing material between the arc tube bulb 1 and the closing bodies 4 and 4'is made as thin as possible and the sealing material is eluted into the arc tube. The surface area of 5,5 'is preferably as small as possible, and these may be adjusted depending on the amount of the sealing material, the heating method and the end structure of the arc tube. In this method, the sealing material 5,5 '
The melting points of 6 and 6'are preferably as close as possible in order to suppress mutual diffusion of the sealing material components.

Next, the sealing materials 5 and 5'on the inner surface side of the arc tube are used as the first sealing material, and the sealing materials 6 and 6'on the outer surface side of the arc tube are used as the second sealing material. Table 1 shows an example of the test results of lamps manufactured by changing the type and weight ratio of the sealing material.

As is clear from Table 1, in the case of using No. 1 test material, both the first and second sealing materials, which are excellent in airtightness and have a good coefficient of thermal expansion and alumina ceramic, are used. It can be seen that the metal halide is consumed during the lighting of the lamp due to the poor property, and the lamp characteristics largely change at an early stage. When both the first and second sealing materials with excellent halogen resistance were used, as in Test No. 2, the thermal expansion coefficient of the alumina ceramic and sealing material did not match, so the lamp blinked. It can be seen that due to the heat cycle caused by, leakage or peeling of the brazed portion occurs early, resulting in poor airtightness. However, as in Test Nos. 3 to 9, a material having excellent halogen resistance was used as the first sealing material, and a material having excellent airtightness in which the coefficient of thermal expansion was well matched with that of the alumina ceramic as the second sealing material. If you use and adjust the ratio,
It can be seen that the thermal stress applied to the brazed portion by the sealing material can be suppressed, and the airtightness and halogen resistance in this portion can be improved. Even if a leak occurs only in the brazing part of the first sealing material, if the weight ratio of the first sealing material to the second is set to 2: 8 or more, the halogen resistance is inferior. It is conceivable that the contact with the sealing material of 2 is slight and the effect on the lamp characteristics can be neglected in practical use. This is Al ₂ O ₃ · SiO ₂ · La ₂ as the first sealing material.
Similar results were obtained when O ₃ or the like was used. Therefore, in order to make the thermal expansion coefficient of the first sealing material closer to that of alumina, the composition ratio of the sealing material may be changed, and Mg having poor halogen resistance may be used.
It is not necessary to add an additive such as O or TiO ₂ more than necessary, and it is possible to make the component (ratio) with emphasis on halogen resistance and melting point.

FIG. 3 is a sectional view of one end of an arc tube showing another embodiment of the metal vapor discharge lamp according to the present invention.

In the embodiment of the present invention, as in FIG. 2, the arc tube bulb 1 is hermetically brazed by the sealing materials 5 and 6 with the closing body 8 made of a conductive ceramic to which the electrode 2 is attached. The closing body 8 is made by integrally baking and solidifying alumina powder and tungsten powder, for example, and has a coefficient of thermal expansion close to that of alumina and conductivity.

Incidentally, the present invention is not limited to the one using a metal halide as the arc tube enclosure as in the above-mentioned embodiment, but a metal such as sodium or cesium or a metal compound other than halogen is used as the arc tube enclosure. The same effect can be obtained even if it is one, and other than alumina as the arc tube bulb and the closing body can be applied.

Effects of the Invention As described in detail above, the metal vapor discharge lamp according to the present invention,
With respect to the filling material in the arc tube, the sealing material is divided into two types, one that emphasizes corrosion resistance and the other that emphasizes airtightness, and by applying these to the same sealing part, the defects of each sealing material can be captured. It has excellent lamp characteristics and life characteristics and high reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an arc tube of a metal halide lamp according to the present invention, FIG. 2 is an enlarged sectional view of one end of the arc tube of FIG. 1, and FIG. FIG. 3 is a cross-sectional view at one end of an arc tube showing the embodiment of 1 ... Arc tube bulb, 2, 2 '... Electrode, 4, 4' ... Closure body,
5,5 ′, 6,6 ′ …… Sealant

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeyuki Mori No. 1 Nishinosho Inonobabacho, Kichijoin, Minami-ku, Kyoto Prefecture Kyoto Prefecture Shinji Uematsu Examiner, Nihon Battery Co., Ltd.

Claims (1)

[Claims] 1. A metal vapor discharge lamp using an arc tube in which both ends of a translucent ceramic tube are hermetically sealed with a sealing body and a metal or a metal compound is sealed inside, and the translucent ceramic tube is sealed. Between the bodies, the inner surface of the arc tube is brazed with a sealing material having excellent corrosion resistance against the enclosure of the arc tube, and the outer surface of the arc tube is brazed with a sealing material having excellent airtightness. A metal vapor discharge lamp.