JPH09274890A - Ceramic discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic discharge lamp of high wattage, of which seal part has the excellent durability in relation to the heat cycle by the flash of a lamp, by using an electrode support formed of a heat resistant metal tube body for airtight sealing of a light emitting tube, and brazing the light emitting tube and the electrode support with silicon wax. SOLUTION: An electrode core 10 passing through a ceramic tube body 11 and a heat resistant metal tube body 12 is fixed to the heat resistant metal tube body 12 by mechanical caulking of a caulking part 13 provided in one end of the heat resistant metal tube body 12. The heat resistant metal tube body 12 is brazed to an end of a transparent alumina tube 1 as a light emitting tube by using the wax material, which is mainly composed of silicon. With this structure, since an electrode at a large diameter can be used by using the heat resistant metal tube body 12, high wattage is obtained, and since the transparent alumina tube 1 and the heat resistant metal tube body 12 are brazed by using the wax material 6, which is mainly composed of silicon, a ceramic discharge lamp, of which seal part has the excellent durability in relation to the heat cycle by the flash of the lamp, is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic discharge lamp using a translucent ceramic as an arc tube bulb.

[0002]

2. Description of the Related Art Translucent alumina tubes have been used in arc tubes of high-pressure sodium lamps, taking advantage of the property of being stable against alkali metals. In recent years, attempts have been made to use this translucent alumina tube as an arc tube of a metal halide lamp in which a metal halide is sealed. The purpose of using alumina tubes for metal halide lamps is
This is because it is more chemically and thermally stable to a metal halide that is an enclosed material than quartz glass that is generally used for arc tubes in conventional metal halide lamps.

In a conventional quartz metal halide lamp,
There is a problem that the life is suppressed by the chemical reaction between the inclusion and the quartz glass. However, the life characteristics can be expected to be improved by using an alumina tube which is chemically more stable than the quartz glass with respect to the inclusion. In addition, it is possible to design a lamp with high efficiency by taking advantage of the characteristic that the operating limit temperature is higher than that of quartz glass, and to encapsulate alkali metals that cannot be sealed because of the high reactivity of quartz glass arc tubes. There is an advantage that there is.

As a method of sealing the arc tube of the ceramic metal halide lamp, as shown in FIGS.
A structure such as 96131 is known. FIG. 1 shows a structure in which an end disk 2 made of ceramic of the same material as that of the arc tube 1 and having a hole for fixing an electrode at one end thereof and coated with metal on the surface of a cylindrical body is sealed with a glass solder 6. 2, a structure in which a cylindrical conductive cermet end disk 7 made of a mixture of alumina and tungsten or molybdenum and having a hole for fixing an electrode at one end thereof is sealed by a glass braze 6 -19
As shown in 6131, there is known a structure in which both ends of the arc tube have a small diameter, and a niobium wire, which penetrates through the opening and fixes the electrode, is sealed with glass solder.

As the glass wax, one containing alumina or calcium oxide as a main component, or one containing alumina or silicon oxide as a main component is used. In the figure, 3 is an electrode,
Reference numeral 4 is a ceramic insulator for preventing back arc, and 5 is a metal coating layer.

[0006]

Prior art FIG. 1 or FIG.
In this structure, the electrodes are directly fixed to an end disk made of ceramic of the same material as the arc tube or an end disk made of cermet which is a mixture of ceramic and metal. In such a structure, a difference in the coefficient of thermal expansion between the end disk and the electrode made of tungsten is unavoidable, and the electrical connection between the electrode and the end disk is made by a thermal cycle by repeatedly turning on and off the lamp. There was a drawback that it was gradually lost and the contact resistance increased. When the electrical connection between the electrode and the end disk is lost and the contact resistance increases, heat is generated at that portion, and the end disk eventually breaks. Then the lamp will stop lighting.

Further, in the sealing structure using niobium wire, it is necessary to reduce the diameter of the openings at both ends of the arc tube in order to secure the reliability of the sealing portion. The reason is that if the diameter of the niobium wire is larger than about 1.5 mm, a leak occurs in the glass brazing portion due to the thermal cycle due to the blinking of the lamp due to the difference in the coefficient of thermal expansion between the ceramic and niobium. Therefore, in order to insert the electrode through the openings at both ends of the arc tube, it is necessary to make the electrode diameter smaller than the diameter of the openings at both ends of the arc tube, and this method can be applied only to a low wattage lamp.

Further, in the sealing structure using the niobium wire, the dimensions of the niobium wire and the electrode are very small, so that it is difficult to join them and the cost is high.

The object of the present invention is to solve such a problem. It has high reliability against a thermal cycle due to blinking of the lamp, can be applied to a high wattage lamp, and can reduce the cost. The present invention provides a ceramic discharge lamp.

[0010]

SUMMARY OF THE INVENTION A ceramic discharge lamp according to the present invention is an arc tube in which an electrode support provided with electrodes is hermetically sealed with glass solder at the openings of both ends of the arc tube made of translucent ceramic. Metal or metal halide and mercury inside,
A ceramic discharge lamp filled with an inert gas is characterized in that the electrode support is composed of a heat-resistant metal tube and a brazing material containing silicon as a main component is used.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A ceramic discharge lamp according to the present invention is provided with an opening at both ends of an arc tube made of transparent ceramics
In a ceramic discharge lamp in which a metal or metal halide, mercury, and an inert gas are enclosed in an arc tube in which an electrode support provided with electrodes is hermetically sealed with glass wax, the electrode support is a heat-resistant metal tube. In this case, a brazing material containing silicon as a main component is used as a brazing material for hermetically sealing the electrode support to the openings at both ends of the arc tube. By doing so, it becomes possible to provide a ceramic discharge lamp which has high reliability in heat cycle, can be applied to a high wattage lamp, and is advantageous in cost.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings.

FIG. 3 is an enlarged sectional view of the electrode support according to the present invention. In the figure, 12 is a heat-resistant metal tube made of Nb-1% Zr, 11 is a ceramic tube made of alumina of the same material as the arc tube, 8 is an outer coil of tungsten, and 9 is an inner coil of tungsten. Reference numeral 10 is an electrode pole core made of tungsten. The electrode pole core 10 penetrates the heat-resistant metal tube body 12 and the ceramic tube body 11, and is fixed to the heat-resistant metal tube body at one end 13 of the heat-resistant metal tube body 12 by mechanical caulking. The ceramic tube body 11 is sandwiched and fixed between the in-electrode coil 9 and the heat-resistant metal tube body 12. It should be noted that the ceramic tube body 11 is for adjusting the protruding length of the electrode into the arc tube and is not necessarily used.

The dimensions of the materials used for the 250 W metal halide lamp arc tube are as follows. The heat-resistant metal tube 12 has an inner diameter of 0.8 mm, an outer diameter of 2.5 mm, and a length of about 6 mm. The ceramic tube 11 has an inner diameter of 0.8 mm, an outer diameter of 2.5 mm, a length of about 6 mm, and an electrode core diameter of 0. 0.7 mm,
The maximum diameter of the electrode coil portion is about 2.1 mm.

FIG. 4 is a sectional view of an arc tube according to the present invention. Reference numeral 1 is an arc tube made of translucent alumina integrally formed with the diameter of both ends smaller than the diameter of the central portion. The inner diameter of the central portion is 16 mm, and the distance between the electrodes is 25 mm. The inner diameter of both ends of the arc tube has two steps, and the outer part of the arc tube is 2.
6 mm, the inner part is 2.2 mm. Silicon brazing is used as the brazing material 6 for hermetically sealing the electrode support and the arc tube. Silicon brazing is used by molding 99.9% Si powder into a ring shape. The melting point of silicon is 1412 ° C., and the brazing is performed at 1430 ° C.

Since the molten silicon brazing material is well melted with the materials of the heat-resistant metal tube body, the ceramic tube, the arc tube and the electrode, the gas-tightness can be obtained completely at the brazing portion. Moreover, since silicon has a coefficient of thermal expansion close to those of these materials, it has excellent durability against thermal cycles. In the figure, the gap between the ceramic tube body 11 and the heat-resistant metal tube body 12 and the gap between these and the translucent alumina tube 1 are intentionally enlarged.

Further, in the present invention, since a hollow heat-resistant metal tube body is used for the electrode support pair, it is possible to absorb heat strain due to a heat cycle better than a metal wire, and reliability of the seal portion. It is excellent and can be used with a large diameter.

The arc tube thus constructed has about 30
The argon gas of torr and the filling material 14 are filled. 20 mg of mercury, 10 mg of scandium iodide as a halide, and 50 of sodium iodide as the encapsulating material
mg is enclosed.

FIG. 5 shows an embodiment of a finished lamp product according to the present invention. The arc tube 1 is incorporated in an outer tube 15 made of quartz, and the inside of the outer tube is kept in a high vacuum. An Al-Zr getter 16 is attached in order to maintain a high vacuum in the outer tube for a long period of time. 250W with such a configuration
When a lamp was prototyped and a lighting test was conducted, it was about 6,000
Even after 0 hour, no abnormalities such as lamp defects occurred.

[0020]

As described above, according to the present invention,
Since the electrode support made of a heat-resistant metal tube is used for hermetically sealing the arc tube, an electrode having a large diameter can be used and a high wattage lamp can be manufactured. Further, since the arc tube and the electrode support are brazed with silicon braze, the durability of the seal portion is excellent against the heat cycle due to the blinking of the lamp, and the life characteristics of the lamp are excellent. Further, since the electrode pole core and the electrode support are brazed with silicon brazing, an electrically highly reliable connection can be obtained, and the processing is simple and the cost can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a sealing structure diagram of a ceramic high-pressure vapor discharge lamp using a conventional metal coating disk.

[Fig. 2] Sealing structure diagram of a ceramic high-pressure vapor discharge lamp using a conventional cermet disk.

FIG. 3 is an overall sectional view of an electrode support according to the present invention.

FIG. 4 is a sectional view of an arc tube according to the present invention.

FIG. 5 is a sectional view of a ceramic discharge lamp according to the present invention.

[Explanation of symbols]

 1 translucent alumina tube 2 metal coating disk 3 electrode 4 insulating plate 5 metal film 6 brazing material 7 cermet disk 8 outer coil 9 inner coil 10 electrode pole core 11 ceramic tube 12 heat-resistant metal tube 13 caulking part 14 Encapsulation material 15 Outer tube 16 Getter

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[Procedure amendment]

[Submission date] June 18, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

Prior art FIG. 1 or FIG.
In this structure, the electrodes are directly fixed to an end disk made of ceramic of the same material as the arc tube or an end disk made of cermet which is a mixture of ceramic and metal. With such a structure, a difference in the coefficient of thermal expansion between the end disk and the electrode made of tungsten is unavoidable, and electrical contact is made between the electrode and the end disk due to the thermal cycle of repeatedly turning on and off the lamp. There was a drawback that it was gradually lost and the contact resistance increased. When the electrical connection between the electrode and the end disk is lost and the contact resistance increases, heat is generated at that part and finally the
The disk will be damaged.

Claims (2)

[Claims] 1. A metal or a metal halide and mercury, and a metal halide or mercury, are contained in an inside of an arc tube formed by hermetically sealing an electrode support provided with an electrode with a brazing material in openings at both ends of the arc tube made of translucent ceramic. In a ceramic discharge lamp filled with active gas,
The ceramic discharge lamp, wherein the electrode support is composed of a heat-resistant metal tube, and the brazing material contains silicon as a main component. 2. The ceramic discharge lamp according to claim 1, wherein the heat-resistant metal tube is made of a heat-resistant metal containing niobium metal as a main component.