JPH08273616A - Sealing part structure of aperture part of metal vapor light emitting tube - Google Patents

Abstract

PURPOSE: To prevent leakage from a sealing part of a metal vapor light emitting tube. CONSTITUTION: A cap 3 is composed of a first, a second, and a third divided caps 3a, 3b, 3c, and the first divided cap 3a is made of either Al2 O3 whose thermal expansion coefficient is equal to that of a material for a light emitting tube or an insulating body having similar thermal expansion coefficient, the second divided cap 3b is made of an insulating body, e.g. Al2 O3 and the third divided cap 3c is made of an insulating body, e.g. a metal having resistance to halogens such as Nb, W, Mo, Pt, etc., or which is metallized with these metals. Through hole are formed in the first divided cap 3a and the second divided cap 3b in the axial direction, an external electrode 5 and an internal electrode 6 are inserted in the holes, an end part of the external electrode 5 coming out of the hole is inserted in a hole 7 formed in the third divided cap 3c, an end part of the internal electrode 6 coming out of the hole is inserted in a hole 8 formed in the third divided cap 3c, and consequently, the external electrode 5 and the internal electrode 6 are electrically connected each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for sealing an opening of a metal vapor arc tube such as a metal halide lamp or a sodium lamp.

[0002]

2. Description of the Related Art A metal vapor arc tube such as a metal halide lamp or sodium lamp is constructed by inserting a light emitting material such as a metal halide or amalgam into the arc tube and then sealing the opening with a cap. By applying a high voltage from the external electrodes between the electrodes, an arc discharge is generated between the internal electrodes, and the metal halide enclosed in the arc tube is evaporated by the heat of this arc discharge, dissociating into metal and halogen, etc. It is designed to emit light having a unique color.

The following means have been considered as means for hermetically sealing the space between the cap and the opening of the arc tube. A cap is made of conductive ceramic, and a space between the cap and the opening is sealed with sealing glass. A conductive film is formed on the outer peripheral surface of the cap made of an insulating ceramic, power is supplied to the internal electrodes through this conductive film, and a space between the conductive film and the opening is sealed with sealing glass. A through hole is formed in a cap made of an insulating ceramic, an electrode rod is inserted into this through hole, and a space between the through hole and the electrode rod and between the cap and the arc tube are sealed with sealing glass. The electrode rod is fixed by utilizing contraction during sintering of the ceramic without sealing the space between the through hole and the electrode rod with sealing glass (Japanese Patent Laid-Open No. 5-198285).

[0004]

In the means for making the cap itself electrically conductive, a sealing glass that seals between the cap and the arc tube due to a large difference in the coefficient of thermal expansion between the cap and the arc tube. Stress concentrates on the
Easy to leak. Further, in the above-mentioned means, since the wettability between the sealing glass and the conductive film is poor, it is easy to leak from this portion. Further, in the above means, since the electrode (metal) is fixed with glass, there is a possibility that leakage may occur over time due to poor wettability with the cap and a difference in coefficient of thermal expansion. Further, in the above-mentioned means, since Mo, W, Re, Nb, Ta or the like is used as the material of the electrode rod, the electrode rod and the cap through hole are not well fitted to each other, and leakage easily occurs from this portion. Moreover, since a metal that is easily oxidized at a high temperature is used, bare lighting cannot be performed.

[0005]

In order to solve the above-mentioned problems, the structure of the sealing portion of the opening of the metal vapor arc tube according to the present invention has a cap to be inserted into the opening as the first, second and third caps. The first split cap is made of the same material as the arc tube material or an insulator having a thermal expansion coefficient similar to that of the arc tube, and the external electrode is inserted therethrough. The second split cap is made of the insulator and the internal electrode. The first of these
The third divided cap provided between the second divided cap and the second divided cap is made of a metal or an insulator whose surface is metallized to electrically connect the external electrode and the internal electrode.

Here, if the sealing glass has flowed to a position where it covers a part of the third split cap, there is no problem in sealing, and as the first split cap, for example, Al ₂ O. _{The third} division cap is made of, for example, Nb, W, Mo, Pt or an insulator obtained by metallizing these metals.

As a concrete example of the structure of the sealing portion,
The structure in which the holes into which the ends of the external electrodes and the internal electrodes are inserted are formed in the split cap, and the first in the third split cap.
Structure in which projections that fit into the holes formed in the split cap and the second split cap are formed, a metal pipe penetrates the first split cap and the second split cap, and the external electrode is attached to the metal pipe. A structure in which the projections formed on the internal electrodes and the third split cap are inserted may be considered.

[0008]

Since the external electrode and the internal electrode are electrically connected via the third split cap interposed in the middle, the leakage through the insertion hole of the electrode is eliminated, and the first electrode located at the outermost position is eliminated. By selecting a split cap whose coefficient of thermal expansion is substantially equal to that of the arc tube, leakage from the gap between the cap and the arc tube opening can be prevented.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a sectional view of a metal vapor arc tube employing a seal structure according to the present invention, FIG. 2 is an enlarged sectional view of FIG. 1, a high-purity polycrystalline alumina (Al ₂ O ₃₎ made of permeable Openings 2 and 2 are formed at both ends of the photoluminescent tube 1, these openings 2 are airtightly closed by a cap 3, and a luminescent substance 4 is enclosed inside.

As shown in FIG. 2, the cap 3 is composed of a first divided cap 3a, a second divided cap 3b and a third divided cap 3c provided therebetween.
The first split cap 3a is made of Al _{2 which} is the same material as the arc tube material.
O ₃ to or from an insulating material the thermal expansion coefficient approximating, the second split cap 3b is made of an insulator such as Al ₂ O _3,
Further, the third divisional cap 3c is made of a halogen-resistant metal such as Nb, W, Mo, Pt, or an insulator in which these metals are metallized.

A through hole is formed in the first split cap 3a in the axial direction, the external electrode 5 is inserted in the through hole, and a through hole is also formed in the second split cap 3b in the axial direction. The internal electrodes 6 are inserted into the through holes, and the ends of the external electrodes 5 and the internal electrodes 6 are formed into the first split cap 3a.
And the protruding end portion of the external electrode 5 protruding from the second split cap 3b has a hole 7 formed in the third split cap 3c.
, And the protruding end of the internal electrode 6 is inserted into the hole 8 formed in the third divided cap 3c, thereby electrically connecting the external electrode 5 and the internal electrode 6.

The insertion of the electrode end into the holes 7 and 8 is
The purpose is to supply power, and there is no need to press it so strongly.
Also, when the naked light is not emitted, P is used as the material of the external electrode 5.
Other than t, for example, a metal such as Mo or W having a melting point higher than the sintering temperature of alumina can be used.

The sealing between the opening 2 and the cap 3 is performed by the sealing glass 9. The sealing glass 9 may be, for example, Al ₂ O ₃ —CaO-based MgO, BeO, S.
What added rO etc. is used. And the sealing glass 9
If the inflow depth of (3) has flowed to a position that covers a part of the third divided cap 3c, specifically about 1/4 of the third divided cap 3c, airtight sealing is guaranteed.

By making the outer diameter of the first divided cap 3a smaller than that of the second and third divided caps 3b and 3c, the sealing glass 9 can be smoothly flowed in.
The first split cap 3a is the second split cap 3b.
Since it may be a low-purity alumina as compared with the above, cost reduction can be achieved.

FIG. 3 is a view showing another embodiment of the cap. In this embodiment, Al ₂ O ₃ is used in place of the bulk of metal in the third divided cap 3c, and this Al ₂ O ₃ is used. The surface of the metal is coated with a metal (Pt etc.) paste 30, and the third
Pt pipe 7 in the holes 7 and 8 formed in the split cap 3c
A and 8a are inserted to ensure the reliability of conduction. A cermet may be used as the third split cap 3c instead of the bulk of metal.

FIG. 4 is a view showing another embodiment of the cap. In this embodiment, the first divided cap 3a and the second divided cap 3b are provided on the surface facing the third divided cap 3c. The recesses 10 and 11 are formed, and the projections 12 that fit into the recesses 10 and 11 are formed on the third split cap 3c.
13 is formed so that positioning when assembling each divided cap can be easily performed.

FIG. 5A is a view showing another embodiment of the cap, and FIG. 5B is a perspective view of the third divided cap. In this embodiment, the shape of the third divided cap 3c is shown. The intermediate portion is closed, and the tubular portion 14 is formed into the first portion.
The split caps 3a and the second split caps 3b are fitted into the recesses 15 and 16 formed on the outer circumferences of the facing surfaces.

FIG. 6 is a view showing another embodiment of the cap. In this embodiment, the first split cap 3 is used.
a and the Pt pipe 1 in the through hole of the second split cap 3b.
7 and 18 are fitted, the external electrodes 5 and the internal electrodes 6 are inserted into the Pt pipes 17 and 18, and the conductive projections 19 and 20 protruding from the third split cap 3c are inserted to the external electrodes 5 and The internal electrodes 6 are electrically connected.

Further, as shown in FIG. 7, the first, second and third split caps 3a, 3b and 3c may be integrated. In this case, the opening 32 formed in the surface of the cap 3 of the radial through hole 31 formed in the cap 3 is tapered, rounded, or chamfered to eliminate sharp edge portions and improve the flow of the Pt paste. A structure that does not cause disconnection may be used. With this structure, the viscosity of the paste can be increased, so that the film thickness can be easily adjusted.

[0020]

According to the present invention as described above,
First, a cap to be inserted into the opening of the metal vapor arc tube,
Divided into second and third divided caps, the first divided cap is made of an insulator having a thermal expansion coefficient equal to or similar to that of the arc tube material, and an external electrode is inserted therethrough, and the second divided cap is made of an insulator. With the internal electrode inserted,
Since the split cap is made of a metal or an insulator whose surface is metallized to electrically connect the external electrode and the internal electrode, a third split in which the external electrode and the internal electrode are interposed in the middle Since it is electrically connected through the cap, there is no leakage through the insertion hole of the electrode, and the first split cap located at the outermost part has a coefficient of thermal expansion substantially equal to that of the arc tube. By making a selection, leakage from the gap between the cap and the arc tube opening can also be prevented.

Also, a structure in which holes for inserting the ends of the external electrodes and the internal electrodes are formed in the third split cap,
By adopting a structure in which the projections that fit into the holes formed in the first split cap and the second split cap are formed in the split caps, the split caps can be accurately positioned. .

Further, the first split cap and the second split cap are penetrated through the metal pipe, and the external electrodes, the internal electrodes and the projections formed on the third split cap are inserted into the metal pipe. At the same time as the positioning, the electrical connection between the external electrode and the internal electrode can be surely performed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a metal vapor arc tube adopting a sealing portion structure according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the main part of FIG.

FIG. 3 is a view showing another embodiment of the cap.

FIG. 4 is a view showing another embodiment of the cap.

5A is a diagram showing another embodiment of the cap, FIG.
Is a perspective view of a third split cap

FIG. 6 is a view showing another embodiment of the cap.

FIG. 7 is a view showing another embodiment of the cap.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Arc tube, 2 ... Opening part, 3 ... Cap, 3a ... 1st division cap, 3b ... 2nd division cap, 3c ... 3rd
Split caps, 5 ... External electrodes, 6 ... Internal electrodes, 7, 8
... hole, 9 ... sealing glass, 10,11 ... recessed part, 12,1
3, 15, 16 ... Protrusion, 17, 18 ... Pt pipe.

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[Procedure amendment]

[Submission date] October 11, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

Since the external electrode and the internal electrode are electrically connected via the third split cap interposed in the middle, the leakage through the insertion hole of the electrode is eliminated, and the first electrode located at the outermost position is eliminated. By selecting a split cap whose coefficient of thermal expansion is substantially the same as that of the arc tube , an unreasonable force is applied to the sealing glass interposed between the cap and the opening of the arc tube.
It can also prevent leaks.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

As shown in FIG. 2, the cap 3 is composed of a first divided cap 3a, a second divided cap 3b and a third divided cap 3c provided therebetween.
The first split cap 3a is made of Al _{2 which} is the same material as the arc tube material.
The second divisional cap 3b is made of an insulator such as O ₃ or a material having a thermal expansion coefficient close to that of Al ₂ O _{3, and the} like.
Furthermore, the third divisional cap 3c is made of Nb, Mo, Pt, etc.
It consists of a metal having a metallic property or an insulator in which these metals are metallized.

Claims (6)

[Claims] 1. In a structure in which a cap is inserted into an opening of a metal vapor arc tube made of translucent ceramic and a gap between the cap and the arc tube is hermetically sealed with a sealing glass, the cap is the first, The first and second split caps are made of the same material as the arc tube material or an insulator having a similar coefficient of thermal expansion, and the external electrode is inserted. The third division cap is made of an insulator and has an internal electrode inserted therethrough. The third division cap is provided between the first and second division caps and has a metal or a surface for electrically connecting the external electrode and the internal electrode. A structure for sealing an opening of a metal vapor arc tube, which is made of a metallized insulator. 2. The sealing structure for an opening of a metal vapor arc tube according to claim 1, wherein the sealing glass has flowed to a position over a part of the third split cap. The structure for sealing the opening of the metal vapor arc tube. 3. The structure for sealing the opening of the metal vapor arc tube according to claim 1, wherein the first split cap is made of Al ₂ O ₃ and the second split cap is Nb. , W, Mo, Pt or an insulator obtained by metallizing these metals, a sealing structure for an opening of a metal vapor arc tube. 4. The structure for sealing the opening of the metal vapor arc tube according to claim 1, wherein the third split cap has holes into which end portions of external electrodes and internal electrodes are inserted. A sealing part structure of an opening of a metal vapor arc tube, wherein: 5. The sealing structure for an opening of a metal vapor arc tube according to claim 1, wherein the third split cap is formed with a first split cap and a second split cap. A sealing part structure for an opening of a metal vapor arc tube, characterized in that a protrusion that fits into the formed hole is formed. 6. The sealing structure for an opening of a metal vapor arc tube according to claim 5, wherein the first split cap and the second split cap are penetrated by a metal pipe, and the metal pipe is external to the external pipe. A sealing part structure for an opening of a metal vapor arc tube, wherein an electrode, an internal electrode, and a protrusion formed on a third split cap are inserted.