JPH03210748A - Single-sealed metal-vapour discharge lamp - Google Patents

Abstract

PURPOSE:To reduce the irradiation of ultraviolet rays to a getter by cutting the ultraviolet rays irradiated to the getter by a pressure sealed part of an emission tube, and by specifying an interval from a flat surface of the pressure sealed part to the getter. CONSTITUTION:The outer diameter of the sphere of an emission tube 2 in the direction of a pressure sealed part as D1, the thickness of the pressure sealed part as D2, and the angle theta between a flat surface including discharge parts 7 of a pair of electrodes 5 as well as a getter 10, and a flat surface in parallel to the surface of the pressure sealed part, including the boundary between a sphere part 3 and the pressure sealed part, are determined. In order to cut ultraviolet rays irradiated to the getter at the pressure sealed part of the emission tube, an expression I is to be satisfied. For the condition that does not generate the extinction of natrium, an expression II is to be satisfied, where a minimum interval between the sphere 3 of the emission tube and the getter 10 is L1, while the length of the pressure sealed part 4 is H1. The extinction of luminous metal can thus be avoided without enlarging an outer tube 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Industrial Application Field) The present invention relates to a single-sealed small metal vapor discharge lamp that is applied to a small metal halide lamp or the like.

(Prior art) In recent years, small metal vapor discharge lamps have been developed for use in indoor and outdoor lighting, and recently, so-called single-sealed lamps have been developed, in which a pair of electrodes are sealed only at one end of the arc tube. A fixed type structure is being considered.

This single-sealed lamp that has been studied has an arc tube in which an approximately ellipsoidal discharge space is formed, and inside the arc tube, a predetermined amount of mercury, sodium, thallium, and It is filled with metal halides such as, and rare gas for starting.

In addition, in the sealing part located at one end of the arc tube,
A pair of electrodes are sealed.

The ends of these electrodes on the sealing part side are connected to metal foil conductors such as molybdenum sealed in the crushing sealing part, and the tips of the electrodes that generate electric discharge are bent so that they face each other. The structure is such that discharge occurs between the two.

(Problems to be Solved by the Invention) In the single-sealed metal vapor discharge lamp as described above, the load on the tube wall is generally much larger than that of the conventional double-sealed discharge lamp. Severe damage and scattering at the tip of the electrode that causes discharge.

In addition, the distance between opposing electrodes is extremely small compared to resealable discharge lamps, so even if the electrode parts that normally generate discharge scatter and disappear, the distance between the parts of the electrodes on the sealed side The discharge is maintained.

In this way, if the discharge is maintained between the parts of the electrode on the sealing part side after the electrode part that originally causes discharge is scattered, the part of the electrode on the sealing part side becomes extremely high temperature. Therefore, there was a risk that the crushing sealing portion that seals the electrodes would melt locally, causing problems such as bursting of the arc tube.

The present invention aims to provide a single-sealed carved metal vapor discharge lamp that can eliminate problems such as bursting of the arc tube by preventing discharge at the end of the lamp life.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the single-sealed carved metal vapor discharge lamp of the present invention has a discharge space filled with a starting rare gas, a luminescent metal, and mercury; The discharge space is equipped with an arc tube having a crushing seal formed at one end of the discharge space and a pair of electrodes that are sealed to the crushing seal and causing discharge, and the electrodes are on the side of the crushing seal. It has a projecting-shaped part that is more easily deformed by discharge than the part that causes discharge, and furthermore, a difficult-to-discharge part that prevents discharge is formed on the side of the crushing sealing part of the projecting part. do.

(Function) The electrode of the present invention has a projecting portion on the side of the crushing sealing portion that is more easily deformed by discharge than the portion that causes discharge, and furthermore, the side of the crushing sealing portion of the projecting portion is more likely to deform due to discharge. Because a difficult-to-discharge area is formed that prevents discharge, if the point of discharge moves toward the crushing sealing part at the end of the lamp life, the electrode will be scattered and deformed due to the discharge in the projecting part, and the difficult-to-discharge area will To provide a single-sealed carved metal vapor discharge lamp which prevents discharge from occurring after that and eliminates troubles such as bursting of an arc tube.

(Example) An example of the present invention will be described below in detail with reference to the drawings.

As shown in the drawing, an embodiment of a single-sealed metal vapor discharge lamp with a lamp input power of 150 W according to the present invention, a predetermined amount of mercury, metal halides such as sodium, thallium, and indium, and a starting material are sealed. The arc tube 1 is made of a heat-resistant and translucent material such as quartz, and has a discharge space 2 having a substantially elliptical spherical shape, and a crushing sealing portion 3 is provided at one end in the short direction of the bulb. .

Further, the ends of the electrodes 4 are each sealed to the crushing sealing part 3 so that the pair of electrodes 4 are spaced apart in the width direction of the crushing sealing part 3 of the arc tube 1, and the other electrodes 4 are sealed to the crushing sealing part 3. The ends are bent to face each other in order to stably generate electric discharge.

Here, a coil made of tungsten with a wire diameter of 0.51 mm or thoriated tungsten containing about 2% thorium is wound around the tip portion 5 of the electrode 4 that generates the discharge, and scattering due to the discharge Deformation is reduced.

Further, the electrode portion 6 located on the side of the crushing sealing portion 3 has a wire diameter of 0.
A metal foil conductor 7 made of, for example, molybdenum, is made of a 5 mm rhenium-tungsten alloy, and its ends are crushed and sealed.
are connected to each other.

A tube 8 made of quartz glass and having an outer diameter of 2 ml and an inner diameter of 0.5 m is fixed in the middle of the electrode portion located on the side of the crushing sealing part 3.

According to the above embodiment, even if the tip of the electrode that originally generates discharge is damaged by scattering over the life of the lamp and the point where the discharge occurs moves toward the collapsed sealing section, it will still be located on the crushing sealing section side. Since the electrode portion 6 that generates the discharge is formed of a rhenium-tungsten alloy having a lower melting point than the tip portion of the electrode that causes the discharge, that portion quickly undergoes melting and deformation.

In addition, since the tube 8 which is difficult to discharge is fixedly formed on the side closer to the crushing sealing part than the projecting part 6, after the easily deformable part 6 formed of rhenium-tungsten alloy is fused and deformed. The discharge is blocked at the difficult-to-discharge portion 8, and the discharge is not maintained.

Due to the above-described effects, the single-sealed metal vapor discharge lamp of this embodiment can eliminate problems such as bursting of the arc tube, which tends to occur at the end of the lamp life.

In the above embodiment, the difficult-to-discharge part of the electrode is formed using a quartz glass tube, but it is also possible to apply a discharging material such as alumina. Various modifications are possible, such as making the entire area closer to the crushing sealing part than the easily deformable area to be a difficult-to-discharge area.

Furthermore, for easily deformable parts, rhenium (Re
), etc., which has a lower melting temperature than the part where the discharge occurs, for example, the part may be locally made thinner to create a structure that promotes deformation due to the discharge.

In addition, if the easily deformable part is formed using rhenium or a rhenium alloy, the surface tension of that metal is large, so when it is melted and deformed by electric discharge, the end part will draw a roughly circular arc. Since it is deformed, in other words, it is deformed into a shape that makes it difficult for discharge to occur, there is an advantage that the effect of enhancing the discharge extinguishing effect becomes remarkable.

[Effects of the Invention 1] According to the present invention described above, there is a discharge space in which a starting rare gas, a luminescent metal, and mercury are sealed, a crushing sealing part formed at one end of the discharge space, and a sealing in the crushing sealing part. The arc tube includes a pair of electrodes that are attached to each other and generate an electric discharge, and the electrodes have a brace-shaped part on the side of the crushed sealing part that is more easily deformed by the electric discharge than a part that causes the electric discharge. Since a difficult-to-discharge area is formed on the side of the compressed sealing part of the braced area, it is possible to prevent discharge at the end of the lamp's life, thereby eliminating problems such as bursting of the arc tube. We can provide single-seal carved metal vapor discharge lamps.

[Brief explanation of drawings]

The drawing is a schematic diagram showing a single-sealed metal vapor discharge lamp according to an embodiment of the present invention.

Claims (1)

[Claims] a discharge space in which a starting rare gas, a luminescent metal, and mercury are sealed; a crush sealing portion formed at one end of the discharge space;
A luminous tube is provided with a pair of electrodes that are sealed to the crushing sealing part and causing discharge, and the electrodes are more easily deformed by the discharge than a part of the crushing sealing part that causes the discharge. 1. A single-sealed metal vapor discharge lamp characterized in that it has an easily deformable part, and a difficult-to-discharge part that prevents discharge is formed on the crush sealing part side of the easily deformable part.