JPS6081757A - Metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To enable temperature of a coldest part of a luminous lamp to be raised and increase resistance against halogen by integrally forming an electrode shaft of an electrode and at least one part of a closed body with cermet being conductive ceramics. CONSTITUTION:A closed body 3 is made of ceramic, e.g., a mixed sintered material of metal powder such as tungsten and alumina ceramics, and an end part of a luminous tube valve 1 is hermetically sealed via glass solder 2 taking as a main component a sealing material such as Al2O3, CaO, etc. A convex part 3b is integrally formed on one end surface of the aforesaid closed body 3 on the inside of the luminous tube so as to form an electrode shaft, and an electrode coil 4b is wound around the aforesaid convex part 3b to construct an electrode 4. Hereby, there is not required a specific means for mounting the electrode shaft on the closed body without a risk of attack by halogen.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a metal vapor discharge lamp using a light-transmitting ceramic tube as an arc tube pulp.

[Technical background of the invention and its problems]

Conventionally, in metal vapor discharge lamps that use translucent ceramics as the arc tube pulp, it is difficult to heat and soften the end of the 70-tube tube and seal it by crushing it, unlike in quartz glass arc tube bulbs. &fThe end of the tube is sealed using a closure made of heat-resistant metal niobium or ceramics.

Furthermore, in recent years, a technique using conductive ceramics, ie, cermet, as a material for the above-mentioned closing body has been published. In this case, the cermet closure also serves as an electricity introducing body. An analogy.

Japanese Patent Publication No. 56-29335 discloses a means for increasing the temperature near the end sealing part of the arc tube, that is, the temperature of the coldest part, by increasing the electrical resistance of the cermet closing body, thereby improving the lamp efficiency. It is shown.

In addition, metal halides such as niobium or tantalum are generally used as the electricity introduction material into the translucent ceramic arc tube sealed with the niobium or ceramic closure. When metals such as niobium are attacked by the above-mentioned niobium and chloride compounds, there will be ℃ and cavitation force ζ, but if a cermet closure body is used as the electricity introduction body, such disadvantages can be avoided. There is also the advantage that it does not occur.

However, while the use of a cermet closure has the above-mentioned advantages, it also has the disadvantage that it does not support the electrode well.

For example, in the above-mentioned Japanese Patent Publication No. 56-29335, as shown in FIG. (3) and an electrode support structure is shown in which an electrode support (5) made of, for example, molybdenum and supporting an electrode (4) is attached to the closure (3). However, with this method, strong adhesion cannot be obtained due to the difference in thermal expansion coefficient between the electrode support (5) and the cermet closure (3). There was also a drawback that the gas sealed in the arc tube could leak due to falling off from the body (3) or cracks occurring in the closing body (31).

In Japanese Patent Application Laid-open No. 57-210560, as shown in FIG. 2, a male screw portion (4a) is provided at the base of the electrode (4).

The screw receiver provided on the cermet closure (3) is located at the part (3a).
A method is shown in which the electrode (4) is supported by the closure body (3) by screwing the male threaded portion (4a) into the closure body (3).

However, this method requires the labor and effort of cutting screws in cermet having a high degree of hardness, and it cannot be said to be a practical method in terms of cost, so it has not been put to practical use.

[Purpose of the invention]

The present invention has been made to address the above problems.

It is an object of the present invention to provide a metal vapor discharge lamp having an arc tube sealing part that supports electrodes easily and reliably, allows raising the temperature of the arc tube sealing part, and has high resistance to halogen.

[Summary of the invention]

The present invention provides a metal vapor discharge lamp equipped with an arc tube in which the end of a translucent ceramic tube is sealed with a closure body that supports an electrode having a coil wound around the electrode shaft. It is characterized by being integrally molded with at least a portion of cermet, which is a conductive ceramic.

[Embodiments of the invention]

The details of the present invention will be explained below with reference to the illustrated embodiments. Figure 3 shows the structure of one end of the high-pressure sodium lamp arc tube. (1) is the arc tube pulp made of translucent ceramics, such as translucent alumina ceramics, and (3) is the closing body made of cermet, such as tungsten. The ends of the arc tube pulp (11) are hermetically sealed via a glass solder (2) which is made of a mixed sintered body of metal powder and alumina ceramics and whose main components are Al, α, CaO, etc. A convex portion (3b) is integrally molded on one end surface of the inner side of the arc tube of this closing body (3) so as to serve as an electrode axis.
A K electrode coil (4b) is wound around this convex portion (3b) to form an electrode (4).

According to such a configuration, the cermet closure body (3)
In addition to its role as a closure for sealing the end of the arc tube, it also serves as an electricity introducing body, and the convex portion (3b) that becomes the electrode axis and the main body of the closure (3) are made of cermet material. Since it is integrally molded, there is no need for special means for attaching the electrode shaft to the occluder as in the past, and there is no need for the electrode shaft to separate from the occluder or to attach the electrode shaft to the occluder. Naturally, problems such as cracks will not occur.

1. When a metal halide is sealed in the arc tube as in a metal halide lamp, 9. The electrical conductor in the part of the arc tube that comes into contact with the halogen is made of cermet, which has strong resistance to halogen, as described above. It also has the advantage that it is not corroded by halogens, unlike when conventional niobium or tantalum electrical introduction bodies are used.

FIGS. 4 and 5 each show other embodiments.

The closure body (3) is composed of two parts made of different materials, and the same parts will be designated by the same reference numerals and the explanation will be omitted. In the embodiment shown in the fourth figure, the main body (3C) of the closure body (3) is made of ordinary ceramics, such as alumina ceramics, and a part (3d) of the closure body (3) is formed with a convex portion (3b) that becomes the electrode axis. A rod-shaped body (3A) with the same outer diameter is integrally molded with cermet, and this rod-shaped body (3A) is used as the main body (3c) of the closure body.
Place it so that it penetrates the center.

Both are hermetically sealed with glass solder (2).

With such a configuration, there is no need to take the trouble to mold the convex portion (3b) of the cermet as in the previous embodiment shown in FIG. The same effects as in the previous embodiment can be obtained with just the effort of assembling. Moreover, if one end of the rod-shaped body (3A) is led out of the arc tube as shown, it can also serve as a current introduction terminal.

The one shown in Figure 5 has a convex part (3b) that becomes an electrode axis formed integrally with cermet on a part (3e) forming the center of the closure, and the outer periphery of the part (3e) forming the center of the closure. The outer shell (3f) is made of the same ceramic material as the arc tube pulp (1) to form a closing body (3).2 The arc tube pulp (1) and the glass solder (2 ) and the outer shell part (3f) of the closure body to be sealed via the sealing body. It is extremely effective in preventing this. In addition, the tip of the protrusion (3b) that becomes the electrode axis is connected to the electrode coil (4b) as shown in the figure.
It may also be made to protrude from.

2. The cermet used in the present invention has a ceramic component that is the same as the ceramic material that constitutes the ceramic that forms part of the arc tube nozzle or the closing body, or preferable.

〔Effect of the invention〕

As detailed above, one aspect of the present invention is that the electrode axis of the electrode and the closing body or a part of the closing body are integrally molded with cermet.
It is completely unnecessary to attach the electrode shaft to the closing body as in the past, and the electrode shaft detaches from the closing body and falls into the arc tube.

Accidents such as cracks occurring from the electrode shaft protrusion of the closing body can be completely prevented. In addition, since the closing body is made of cermet, it can function as a current introducing body and increase the temperature of the tube end, that is, the coldest part of the arc tube, thereby improving luminous efficiency.Furthermore, in metal halide lamps, the current introducing body is eroded by halogen. It also has a remarkable effect on prevention.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views of one end of a conventional arc tube;
FIG. 3 is a sectional view of one end of an arc tube according to an embodiment of the present invention;
FIGS. 4 and 5 respectively show cross-sectional views of one end of the arc tube of another embodiment. (1)・・・・・・Light saving bulb (2)・・・
...Glass solder (3) ...Closing body (3b) ...Cermet electrode shaft (4)
...... Electrode (4b)... Electrode coil (3A)... Cermet rod-shaped agent
Patent Attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2a Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A luminous tube sealed with a closure body supporting an electrode formed by winding a coil around an electrode shaft at the end of a translucent ceramic tube; A metal vapor discharge lamp characterized by being made of an integrally formed conductive cermet. (2) The metal vapor discharge lamp according to claim 1, wherein the electrode shaft of the electrode and a part of the closing body are made of cermet integrally molded into a rod-shaped body having the same outer diameter.