JPH0541497Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a high-pressure metal vapor discharge lamp (hereinafter referred to as HID).
The present invention relates to a conductive closing body at the end of a luminous tube (abbreviated as a lamp), and more specifically, to a structure for embedding electrodes and/or lead members provided in a conductive cermet end cap as a conductive closing body. It is.

(Prior Art) Conventionally, as disclosed in Japanese Patent Laid-Open No. 71695/1983, as an arc tube end closure body in an HID lamp using a translucent ceramic tube as an arc tube, A conductive disk (end cap) is provided. Such a conductive disk is made of, for example, a conductive cermet made by mixing and sintering aluminum oxide powder and metal tungsten powder. A tungsten discharge electrode is provided on the inside of the arc tube of such a conductive cermet disk, while a lead member connected to a power source is provided on the outer surface of the conductive cermet disk. is embedded and fixed therein, and power from the power supply is supplied from the lead member to the tungsten electrode through the conductive cermet disk.

The reason for using a conductive cermet disk with such a structure is that, when applied to a high-pressure sodium lamp, for example, an inexpensive tungsten electrode can be used instead of an expensive niobium electrode, and a transparent ceramic disk can be used instead of an expensive niobium electrode. A suitable light-emitting metal halide is sealed in the interior of the arc tube, along with mercury and a rare gas, to improve color rendering.
This is because when applied to a so-called metal hydride lamp, it has corrosion resistance against such halides.

However, in the case of such a conductive cermet disk, in order to embed and fix predetermined tungsten electrodes and lead members in the cermet disk, a cermet disk green body in which the tungsten electrodes and lead members are embedded is required. When sintering and integrating the cermet disc materials into one, the shrinkage of the green body and the excessively large difference in thermal expansion between the cermet disk material itself and the tungsten electrodes and lead members reduce the resulting electrical conductivity. Cracks tend to occur in the disks of the lamps, and as a result, the arc tube leaks, leading to problems such as a decrease in luminous flux and non-lighting.

For this reason, the inventors of the present invention first
No. 88658 discloses a structure in which stranded wires are used as electrodes and/or lead members embedded in a conductive closure at the end of an arc tube, and also in 1986-
Publication No. 58456 discloses an improved structure in which the electrode shaft and the like are buried in the hole of the end cap together with a wire that is thinner and lower in height than the electrode shaft. In either end structure, it is possible to effectively prevent cracks from occurring around the electrode or lead member of the end cap made of cermet.

(Problem that the invention attempts to solve) However, recently,
In the latest structure of the arc tube disclosed in Publication No. 58456, in which strands are inserted and buried, the following problems have occurred.

(1) Before firing, it takes time and effort to insert the corresponding electrode shaft and lead member together with the wire into the jig and the hole in the cermet end cap.

(2) Since the wires are attached to the electrode shafts and lead members and buried, there is little contact with the inner periphery of the burying hole, resulting in variations in the resistance value during the manufacturing of cermet end caps. Due to the difference in thermal expansion and oxidation between the cermet end cap and the cermet end cap, the contact between the inner periphery of the buried hole is broken, the resistance value of the cermet end cap increases, heat is generated, and cracks occur. Furthermore, since the wire is buried along the electrode axis, the electrode axis does not stand vertically after firing. Using such an end closure
The arc tube for HID lamps has variations in the coldest point,
Due to variations in the temperature distribution of the arc tube wall, it is difficult to obtain a lamp with stable quality, a high luminous flux maintenance rate, and a long lamp life.

The purpose of this invention is to solve the above-mentioned problems, prevent the occurrence of cracks in the cermet end cap as a conductive closing body, and prevent the occurrence of leaks in the arc tube, while also reducing the blackening of the wall of the arc tube during lighting. The object of the present invention is to provide an arc tube for an HID lamp that can reduce the amount of heat generated, improve work efficiency, reduce the number of parts, and further suppress an increase in the resistance value of the cermet end cap, thereby extending the life of the lamp.

(Means for Solving the Problems) The arc tube for a high-pressure metal vapor discharge lamp of the present invention has an end of a translucent ceramic tube closed with a conductive cermet end cap, and an electrode shaft inside.
In an arc tube for a high-pressure metal vapor discharge lamp in which a lead member is placed on the outside and each end thereof is buried in a buried hole provided in the end cap, a lead member is provided in at least one of the buried holes substantially parallel to the axial direction of the buried hole. Provide a secondary hole with approximately the same depth as the buried hole,
At least one of the electrode shaft and the lead member,
The device is characterized in that it is buried in a buried hole having a sub-hole, with a cavity defined by the sub-hole having the same depth as the depth at which the device is buried.

Here, the shape of the sub-hole does not matter as long as it has a structure in which a part of the buried hole is cut out, and the number of sub-holes is not limited to one. It is a concept that includes things.

(Function) In the above-described configuration, by providing a sub-hole in the embedding hole which is approximately parallel to the axial direction of the embedding hole and has approximately the same depth as the embedding hole, when the electrode shaft and/or lead member are integrated with the embedding hole provided in the cermet end cap by firing, it is possible to effectively prevent cracks from occurring due to the difference in thermal expansion of the two components, and it is possible to maintain a high contact rate between the electrode shaft and/or lead member and the embedding hole, so that it is possible to effectively prevent increases and variations in the resistance value of the cermet end cap and extend the lamp life.

Further, the contact ratio between the electrode shaft and the lead member and the inner circumferential surface of the buried hole after firing is 50 to 98%, preferably 50 to 80%. If the contact ratio is less than 50%, the contact area between the electrode and/or lead member and the cermet decreases, resulting in a decrease in the reliability of the mechanical connection between the two, and furthermore, the resistance after the lamp is turned on decreases. It is preferable that the contact ratio is 50 to 98%, since the increase in the value becomes large and if it exceeds 98%, it becomes difficult to control the manufacturing method and cracks may occur in the cermet end cap.

(Example) Fig. 1 schematically shows the entire HID lamp to which the present invention is applied, in which 2 is a light-transmitting bulb (outer bulb) generally made of glass or the like; By closing the opening of the valve 2 with the base 4, the sealing performance within the valve 2 is ensured. This valve 2 is normally 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 connected 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 now being supplied by

The arc tube 6 includes a tube-shaped translucent ceramic tube 12 made of alumina porcelain or the like, and conductive disks (cermet) 1 fixed to both ends of the tube and serving as end caps for sealing the tube.
4 and 14. Then, the lead member 8 is connected to the conductive disk 14.
At the same time, a predetermined electrode 16 is buried at one end of the arc tube 6, and various metals or their vapors are sealed in the arc tube 6 depending on the type of HID lamp, such as high-pressure sodium. Lamps are filled with metallic sodium, mercury, and rare gases, and metal halide lamps are filled with mercury and rare gases, as well as halides of appropriate light-emitting metals (disprosium iodide, iodide, etc.). thallium, sodium iodide, indium iodide, etc.).

FIG. 2 is a diagram showing the end structure of the arc tube of the present invention. In FIG. 2, the same members as those shown in FIG. 1 are given the same reference numerals, and their explanations will be omitted. In this embodiment, each of the buried holes 21a and 21b for the electrode 16 and the lead member 8 is provided with sub-holes 22a and 22b having the same depth as each of the buried holes. Further, a coil portion 23 is provided at the tip of the electrode 16 as is conventionally known, and an insulating layer 25 for preventing back arcing is provided on the discharge surface 24 of the conductive disk 14 on the electrode 16 side. This insulating layer 25 may be provided over the entire surface of the discharge surface 24 as shown in FIG. 2, or may be provided so as to cover a portion thereof.

As described above, the electrode 16 and the lead member 8 are buried in the embedding holes 21a and 21b having the sub-holes 22a and 22b.
After standing up as shown in Figure a, it is sintered at high temperature and shrink-fitted. Then, as shown in FIG. 3b, which also shows a negative cross-section, the stress generated by shrink fitting is mainly alleviated due to thermal deformation of the cross-sectional shape of the sub-hole 22a, and at the same time, a good electrical contact state and sufficient Shrink fit strength can be ensured.

In addition, in order to make the sub-holes 22a, 22b of the present invention, after drilling the buried holes 2a, 2b in the conductive disk 14 in advance, the sub-holes 22a, 22b are formed.
A method of drilling similarly, buried holes 21a, 2
1b and the sub-holes 22a, 22b are preferably mechanically press-molded at the same time as the conductive disk 14 is formed. In this case, it is preferable that the sub-hole is shaped like a curved surface for embedding the electrode shaft, since this makes it easier to adjust the contact surface (close contact surface) between the electrode shaft and the conductive disk, and also prevents cracks. In addition, in order to minimize intrusion into the space between the metal halide, it is desirable that the center of the sub-hole be located within the buried hole.

FIGS. 4a and 4b are cross-sectional views showing configurations of other examples of the shape of the sub-holes, respectively. All of them show the shapes before firing, and are examples in which a plurality of sub-holes were provided in the surrounding wall of the buried hole. Here, the shape of the sub-hole can be selected as appropriate, such as semicircular, triangular, or square.

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 for the electrodes 16 and lead members 8. For example, a composite consisting of metallic tungsten or metallic molybdenum and aluminum oxide, tungsten carbide, tungsten boride, etc. are used. Further, the electrode 16 of the conductive disk 14
The insulating layer provided on the side surface is appropriately formed using a known insulating material.

Furthermore, as in this embodiment, it is most desirable to provide a buried hole and a sub-hole on both the electrode 16 side and the lead member 8 side to construct the intended end closure body. If a secondary hole is provided in the embedding hole at least on either the electrode side or the lead member or only on one side of the arc tube,
It is possible to achieve that goal.

The HID lamp according to the present invention using a closing body in which the electrode 16 is buried in a predetermined buried hole and a sub-hole is a metal halide lamp in which a translucent ceramic tube is used as the constituent material of the arc tube 6. Examples include lamps, high pressure sodium lamps, and the like.

(Effects of the invention) As is clear from the above explanation, according to the arc tube for a high-pressure metal vapor discharge lamp of the invention, the luminous tube for a high-pressure metal vapor discharge lamp of the invention has a depth that is approximately parallel to the axial direction of the buried hole and approximately the same depth as the buried hole. By providing a sub-hole, it is possible to prevent cracks in the cermet end cap and leaks in the arc tube, while also effectively suppressing blackening of the wall of the arc tube during lighting. It is possible to reduce the number of points, and also to suppress the increase in the resistance value of the cermet end cap, thereby extending the lamp life.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the overall configuration of an HID lamp to which the present invention is applied, Fig. 2 is a diagram showing the end structure of the arc tube of the present invention, and Figs. A sectional view showing the structure of one example of the sub-hole after firing, and FIGS. 4A and 4B are views showing the structure of other examples of the sub-hole of the present invention, respectively. 2... Bulb, 4... Base, 6... Luminous tube, 8
... Lead member, 10 ... Conductive member, 12 ...
Translucent ceramic tube, 14... conductive disk, 16... electrode, 21a, 21b... buried hole,
22a, 22b...Sub-hole, 23...Coil part, 2
4...Discharge surface, 25...Insulating layer.

Claims (1)

[Claims for Utility Model Registration] 1. The end of a translucent ceramic tube is closed with a conductive cermet end cap, and an electrode shaft is placed inside and a lead member is placed outside, and the end cap is closed at each end. In the arc tube for a high-pressure metal vapor discharge lamp which is buried in a buried hole provided in the buried hole, at least one of the buried holes is provided with a sub-hole that is substantially parallel to the axial direction of the buried hole and has approximately the same depth as the buried hole. , at least one of the electrode shaft and the lead member is buried in a buried hole having a sub-hole, with a cavity defined by the sub-hole having the same depth as the depth at which the electrode shaft and the lead member are buried. Arc tube for high pressure metal vapor discharge lamp. 2. The high-pressure metal vapor release method according to claim 1, wherein the contact ratio between the inner peripheral surface of the buried hole corresponding to the electrode shaft and the lead member and the electrode shaft and the lead member is 50 to 98% of the inner peripheral surface of the buried hole after firing. Luminous tube for electric lights.