JPH06223783A - Discharge lamp and its manufacture - Google Patents

Abstract

PURPOSE:To provide a configuration and its manufacture, which enables a metallic foil mainly composed of molybdenum used for the sealing section of a discharge lamp employed by the various kinds of lighting equipment and the like to be easily and firmly welded to an electrode mainly composed of tungsten. CONSTITUTION:Welding can be done easily and firmly by splicing a metallic foil 3 to an electrode 2 via a thin film 6 mainly composed of platinum coated on the metallic foil 3 and/or the electrode 2. The thin film 6 mainly composed of platinum is formed as follows, a compound layer mainly composed of the metal organic compound of platinum is laminated on the metallic foil 3 and/or the electrode 2 first so as to be subsequently heattreated under a non-oxidizing environment, the way of formation as described above permits the platinum thin film 6 to be formed at a specified position inexpensively through simple processes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp used for various kinds of lighting and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, discharge lamps such as mercury lamps and metal halide lamps have been widely used as light sources for optical equipment, from general lighting such as store lighting and road lighting. There are discharge lamps having various structures, but generally, they have an arc tube formed of quartz glass and a pair of electrodes for causing a discharge in the arc tube. This electrode is connected to an external lead wire via a metal foil and is sealed at the metal foil portion, so that airtightness inside the arc tube can be maintained. Further, as the material of the metal foil, molybdenum or the like having a thermal expansion coefficient close to that of quartz glass is used so that the metal foil can be easily sealed, and tungsten is often used as the electrode material. The electrode and the metal foil were joined by resistance welding.

[0003]

However, since tungsten, which is the electrode material, and molybdenum, which is the material of the metal foil, are different metals, they are difficult to weld. Further, because of this, the welding strength is often insufficient, and there is a problem that the welding is disengaged by the force applied when the arc tube is sealed. For large discharge lamps, a method of sandwiching the platinum foil between the electrode and the metal foil and welding is also used to improve the weldability. In this case, the electrodes, the platinum foil and the metal foil are aligned in three parts. However, there is a problem that resistance welding is required, workability is very poor, and the platinum foil is expensive because it has a thickness of several microns.

The present invention solves the above-mentioned conventional problems, and is a discharge lamp which can be easily welded and has high welding strength.
Another object of the present invention is to provide an inexpensive manufacturing method of the discharge lamp.

[0005]

In order to solve the above-mentioned problems, the present invention comprises a metal foil containing molybdenum as a main component at both ends of an arc tube, and a tungsten main component bonded to one end of the metal foil. And the metal foil and the electrode of the discharge lamp having the external lead wire joined to the other end are joined via the metal foil and / or a thin film containing platinum as a main component coated on the electrode. In a non-oxidizing atmosphere, a thin film containing platinum as a main component is laminated on a metal foil or / and a compound layer containing a metal organic compound of platinum as a main component, and It is a manufacturing method characterized in that it is formed by performing a heat treatment at.

[0006]

According to the present invention, a platinum thin film is coated with a metal foil or /
Moreover, since it is provided at the welded portion on the electrode, the welding can be performed easily and firmly. Further, as compared with the case of using the platinum foil, it is only necessary to align the electrode and the metal foil, so that welding can be performed with good workability. Further, by thermally decomposing the metal-organic compound of platinum, a platinum thin film can be formed at a desired position at a low cost by a simple process of coating and baking, as compared with vapor deposition or the like.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a front view showing the structure of a discharge lamp according to a first embodiment of the present invention. In FIG. 1, 1 is an arc tube made of quartz glass, and 2 is a main component of tungsten. Are connected to the external lead wires 4 via the metal foil 3 containing molybdenum as a main component.
The metal foil 3 is sealed by the sealing portion 5 so that the inside of the arc tube 1 becomes airtight. Reference numeral 6 denotes a platinum thin film coated on the electrode 2, and the electrode 2 is welded to the metal foil 3 via the platinum thin film 6.

FIG. 2 is a view showing a manufacturing process for joining the electrode 2 and the metal foil 3 in FIG. 1. First, the welding position of the tungsten electrode 2 shown in FIG. 2 (1) is shown in FIG. 2 (2). As described above, a solution of platinum metal organic compound 7 dissolved in an organic solvent was dip-coated, and then dried at 100 ° C. for 10 minutes. After that, resistance welding was performed by firing at 500 ° C. for 10 minutes in a nitrogen atmosphere. After firing, the electrode 2 (outer diameter
A thin film 6 of platinum of about 1000Å is formed on 0.71 mm), and as shown in Fig. 2 (4), the resistance welding of the thin film 6 of platinum and the metal foil 3 of molybdenum (thickness 28 microns) Sufficient welding strength was obtained by one welding. When the welding strength was examined by the tensile test, all the breakages were due to the damage of the molybdenum metal foil, and the weld could not be removed.

(Embodiment 2) FIG. 3 shows a manufacturing process for joining electrodes of a discharge lamp and a metal foil in a second embodiment of the present invention. The same members as those in the first embodiment are designated by the same reference numerals as those in FIG. 2 and their explanations are omitted. Figure 2
What is different from the above configuration is that the platinum thin film 6 is provided on the molybdenum metal foil 3.

First, on one end surface of the molybdenum metal foil 3 shown in FIG. 3 (1), the metal organic compound 7 of platinum shown in FIG. 3 (2) is dissolved in an organic solvent and a resin as a binder is added to the ink. As a result, it was printed at the welding position on the metal foil 3 of molybdenum. Then, it was dried at 100 ° C. for 10 minutes and fired at 600 ° C. for 15 minutes in an argon gas atmosphere to perform resistance welding. After firing, as shown in FIG. 3 (3), a thin film 6 of platinum of about 2000 liters was formed on the printed portion on the metal foil 3 of molybdenum, and as shown in FIG. As for welding, sufficient welding strength was obtained by one welding as in the case of Example 1.

As described above, the platinum thin film can be formed on the welded portion by the simple process of printing and firing, and the welding can be easily strengthened.

Although the platinum thin film 6 is provided on either the electrode 2 or the metal foil 3 in Embodiments 1 and 2, it may be provided on both welded portions. Further, in order to soften the oxidation of the electrodes and the metal foil during firing, a metal organic compound of platinum which is thermally decomposed at a low temperature may be used.

[0014]

As described above, according to the present invention, since the platinum thin film is provided on the metal foil or / and the welding portion on the electrode,
Welding can be done easily and firmly. Further, by thermally decomposing the metal organic compound of platinum, a platinum thin film can be formed at a desired position at a low cost by a simple process.

[Brief description of drawings]

FIG. 1 is a front view showing a structure of a discharge lamp according to a first embodiment of the present invention.

FIG. 2 is a manufacturing process diagram for joining the electrode and the metal foil in the first embodiment of the present invention.

FIG. 3 is a manufacturing process diagram of joining an electrode and a metal foil in the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Arc tube, 2 ... Electrode, 3 ... Metal foil, 4 ... External lead wire, 5 ... Sealing part, 6 ... Platinum thin film, 7 ... Platinum metal organic compound.

Front page continuation (72) Inventor Takeyoshi Yonkichi 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Masayuki Wakamiya 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Invention Person Uryu Eiichi 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A metal foil containing molybdenum as a main component, an electrode containing tungsten as a main component bonded to one end of the metal foil, and an external lead wire bonded to the other end of the metal foil in a sealing portion of the arc tube. The discharge lamp, wherein the metal foil and the electrode of the discharge lamp are bonded to each other through a thin film containing platinum as a main component and coated on the metal foil and / or the electrode. 2. A thin film containing platinum as a main component is formed by laminating a compound layer containing a metal organic compound of platinum as a main component on a metal foil or / and an electrode and then heat-treating it in a non-oxidizing atmosphere. A method of manufacturing a discharge lamp, comprising: