JPH0327329Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is a high-pressure metal vapor discharge lamp (hereinafter referred to as HID).
It relates to a conductive closing body for the end of an arc tube (referred to as a lamp), and more specifically, electrodes and leads embedded in a conductive closing body for closing both ends of a translucent ceramic tube constituting an arc tube. It concerns the shape of the member and the hole in which it is buried.

Traditionally, translucent ceramic tubes have been used.
As an end blocker for the arc tube in HID lamps,
Conductive disks have been proposed in Japanese Patent Laid-Open Publication No. 71695/1983. Such a conductive disk is made of, for example, a conductive cermet made by mixing and sintering aluminum oxide powder and metallic tungsten powder, and the portion of this conductive cermet located inside the arc tube contains: A metal tungsten or metal molybdenum electrode is provided, and a rod-shaped lead member is embedded and fixed in the outer surface of the conductive cermet, and power is supplied from the lead member to the tungsten or molybdenum electrode through the conductive cermet. It is becoming more and more common. The reason for using a conductive cermet disk with such a structure is that, when applied to a high-pressure sodium lamp, for example, it avoids the use of expensive niobium metal, and it also avoids the use of the inside of an arc tube made of translucent ceramics. In addition, when applied to a so-called metal halide lamp in which a suitable type of luminescent metal halide is sealed together with mercury and a rare gas, it has halogen resistance.

However, in terms of the required characteristics of such an end closure, conductive cermet
Good electrical contact is required between the disk and a predetermined tungsten or molybdenum electrode and lead member, and in order to meet this requirement, the electrode and lead member are embedded and the cermet disk green body is sintered. When integrating these electrodes and lead members, it was necessary to fix the electrodes and lead members with a predetermined strength or higher due to shrinkage of the green body during the sintering process. However, the difference in thermal expansion between the cermet disk material itself and the tungsten or molybdenum electrodes and lead members is too large, and in the case of the conductive cermet disk obtained in this way, cracks occur in the buried portions of the electrodes and lead members. The occurrence of this was difficult to avoid.

A high-pressure metal vapor discharge lamp manufactured using the end closure body obtained in this way has a leakage of the filling inside the arc tube due to a slight crack in the end closure body when the lamp is lit. There were problems such as a decrease in luminous flux and non-lighting.

The present invention was developed in view of the above circumstances, and its purpose is to provide an arc tube end for HID lamps that does not cause cracks in the conductive disk and does not cause arc tube leaks. In order to achieve this purpose, a twisted material is used as an electrode and/or lead member to be inserted and buried in a hole provided in a conductive disc of such an electrically conductive end part closure member. This method is characterized by the use of wires and the presence of a space between the twisted wires and the inner surface of the hole in which they are buried.

Hereinafter, in order to clarify the present invention more specifically, one embodiment of the present invention will be described in detail based on the drawings.

First, FIG. 1 schematically shows the entire HID lamp to which the present invention is applied, in which 2 is a light-transmitting bulb generally made of glass or the like; By closing the opening of the valve 2 with the base 4, the interior of the valve 2 is sealed. Note that the valve 2 is filled with an inert gas such as nitrogen, or is maintained in a vacuum state. As is well known, conductive members 10, 10 supporting the arc tube 6 are attached to the lead members 8, 8 at both ends of the arc tube 6 housed inside the bulb 2 through the cap 4. Power is supplied through the

Further, the luminous tube 6 is made of a tube-shaped translucent ceramic tube 12 made of alumina porcelain or the like.
and conductive disks 14, 14 as end caps fixed to both ends thereof to seal them.
It is composed of. Then, with respect to the conductive disk 14, together with the lead member 8,
A predetermined electrode 16 is embedded at one end thereof. Further, the sealed translucent ceramic tube 12 of the arc tube 6 is filled with various metals or their vapors depending on the type of HID lamp. For example, in the case of a high-pressure sodium lamp, metallic sodium, Contains mercury and rare gas.
Furthermore, in the case of metal halide lamps, an appropriate type of luminescent metal halide (disprosium iodide, thallium iodide, sodium iodide, indium iodide, etc.) is sealed together with mercury and a rare gas. .

By the way, the present invention provides an embedded electrode 16 of the conductive disk 14 as such an end cap.
The present invention is applied to the lead member 8, in other words, an electrode embedded in the electrically conductive closure at the end of the arc tube, and an example thereof is shown in FIGS. 2 and 4.

That is, in those figures 2 and 4,
The conductive disk 14 is fitted to the end of the translucent ceramic tube 12 of the arc tube 6 with a sealing material 19 such as glass frit, or is shrink-fitted and fixed without using such a sealing material. A lead member 8 made of stranded wires is buried or erected on the outer surface, while the inner surface,
In other words, a stranded wire electrode 16 such as a tungsten or molybdenum electrode is erected on the exposed surface of the translucent ceramic tube 12 with a part of it buried. It is located centrally. An insulating layer 20 for preventing back arcing is provided at a predetermined thickness on the discharge surface 18 of the conductive disk 14 on the electrode 16 side. Note that this insulating layer 2
0 may cover a portion of the discharge surface 18 or the entire surface thereof.

In this way, by using twisted wires for the electrodes 16 and the lead members 8 buried and erected in the conductive disk 14, a buried hole with a circular cross-section of a predetermined depth is formed in the conductive disk 14. When the stranded wire is erected in 21 and sintered at high temperature and sinter-fitted, as shown in FIG. This makes it possible to alleviate the stress generated by shrink-fitting while ensuring good electrical contact and sufficient shrink-fitting strength. That is, in the conventional case, as shown in FIG. 3, since the electrode 16 completely fills the buried hole, the shrinkage stress of the conductive disk 14 cannot be effectively alleviated. However, in the present invention, as shown in FIG.
A space exists between the stranded wires constituting the electrode 16 and the inner surface of the buried hole 21, so that the stranded wires 1 described above
6 and the buried hole 21 become possible, and the shrinkage stress of the disk can be satisfactorily alleviated.

In addition, as for this twisted wire, for example, 2 to 4 twisted 0.2 mmφ to 0.7 mmφ tungsten or molybdenum wires are used, in contrast to the 0.4 mmφ to 1.5 mmφ of conventional metal rod electrodes and lead members. The twist pitch is about 3 to 10 mm/rotation,
Further, the buried depth may be approximately 1.5 mm or more.
The larger the number of stranded wires and the smaller the twisting pitch, the closer the cross-sectional shape of the stranded wires to the circular embedding hole 21 of the conductive disk 14 in contact with the circular embedding hole 21 becomes. The effect of relieving fitting stress is reduced. Furthermore, even if multiple strands of wire are not twisted at all, although the stress can be alleviated, the wires are not organized, which causes troublesome burying work.

As described above, according to the present invention, the occurrence of cracks in the disk, which was conventionally caused due to the difference in thermal expansion between the conductive disk, the rod-shaped electrode, and the lead member, can be avoided.
Furthermore, the occurrence of leakage due to this can be effectively prevented, thereby causing a decrease in luminous flux,
This made it possible to eliminate all problems such as non-lighting.

In this way, various known materials are appropriately selected as the material for the conductive disk 14 used as the end closure of the arc tube 6, but in general, the translucent ceramic tube 12 is used. Any conductive material can be used as long as it has an intermediate coefficient of thermal expansion between the constituent materials and the heat-resistant metal used as the electrode 16 and lead member 8. For example, tungsten metal, molybdenum metal, and aluminum oxide can be used. Composites consisting of tungsten carbide, tungsten boride, etc. are used.

Further, the insulating layer 20 provided on the surface 18 of the conductive disk 14 on the electrode 16 side is appropriately formed using a known insulating material.

Furthermore, although it is most desirable that both the electrode 16 and the lead member 8 be made of stranded wire, even if only one of them is made of stranded wire,
It is possible to achieve some objectives.

Note that the closure body 14 in which the twisted wire electrode and/or lead member is embedded according to the present invention
Examples of HID lamps that can be used include metal halide lamps in which the translucent ceramic tube 12 is used as a constituent material of the arc tube 6, as described above, and high-pressure sodium lamps.

Although a typical example of the present invention shown in the drawings has been described above, the present invention is not to be construed as being limited by the illustrated structure or the specific explanation accompanying it. Without departing from the spirit of the present invention, various changes, modifications, improvements, etc. may be made to the present invention based on the knowledge of those skilled in the art, and the present invention does not include such embodiments. It also includes;
It goes without saying.

As explained above, an HID lamp equipped with an arc tube formed by closing both ends of a translucent ceramic tube with a stranded wire electrode and/or lead member embedded closing body according to the present invention, Since no cracks occur in the conductive disk constituting the lamp, the reliability of the lamp is improved and the luminous flux maintenance rate is high, which is where the great industrial significance of the present invention lies.

[Brief explanation of the drawing]

FIG. 1 is a schematic cutaway diagram showing an example of an HID lamp equipped with an arc tube in which both ends of a translucent ceramic tube are closed with conductive closing bodies embedded in stranded wire electrodes and lead members according to the present invention, and FIG. is like that
FIG. 3 is an explanatory longitudinal cross-sectional view of the main part showing an enlarged end of the arc tube of the HID lamp; FIG. The figure is a cross-sectional view of the conductive disk portion of FIG. 2 according to the present invention,
FIG. 5 is an explanatory cross-sectional view showing the shrink-fitting state of the electrode and the conductive disk, where the solid line is before firing and the broken line is after shrink-fitting. 2: bulb, 4: base, 6: arc tube, 8: lead member, 10: conductive member, 12: translucent ceramic tube, 14: conductive disk, 16: electrode,
18: discharge surface, 19: sealing material, 20: insulating layer, 21: stranded wire embedding hole.

Claims (1)

[Scope of utility model registration request] Inserting the electrode and the lead member at their ends into the buried holes provided in the conductive disk, respectively;
In the electrically conductive closing body for the end of an arc tube for a high-pressure metal vapor discharge lamp which is buried, the electrode and/or the lead member are composed of twisted wires, and a space is provided between the twisted wires and the inner surface of the buried hole. What is claimed is: 1. An arc tube end closure body characterized by the presence of.