JPS59165363A - Electrode for discharge lamp - Google Patents

Abstract

PURPOSE:To quickly stabilize arc spot in starting and increase life of a lamp by arranging inner coils obtained by winding duplex or more tungsten coils in two or more layers on to an electrode core wire and coils which are wound on the outside of the inner coil and have a wire diameter equal to larger than the maximum wire diameter of the inner coil. CONSTITUTION:A discharge lamp electrode 10 consists of an electrode core wire 11 comprising heat resistant metal, inner coils 12 obtained by winding duplex or more tungsten coil in two or more layers on to the core wire 11, and a coil 13 which are wound on the outside of the inner coil 12 and have a wire diameter equal to or larger than the maximum diameter of tungsten wire of the inner coil 12. For example, tungsten wire having a diameter of 0.1mm. is closely wound as the secondary coil on to the primary coil having a diameter of 0.3mm. to form a duplex coil. This coil is wound seven turns as the first layer and seven turns as the second layer. A 0.5mm. diameter tungsten wire is wound 10.5 turns on the outside of the inner coil 12. A 0.9mm. diameter tungsten core wire is inserted into the inner coil 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrodes for discharge lamps, and more particularly to high-pressure vapor discharge lamps such as high-pressure mercury lamps filled with rare gas and mercury, or high-pressure sodium lamps filled with metallic sodium along with rare gas and mercury. Related to electrodes used in etc.

For example, a metal halide lamp is a discharge lamp in which various metal halide compounds are sealed in the arc tube of a high-pressure mercury lamp in order to improve luminous efficiency and color rendering.This arc tube is constructed as shown in Figure 1. It had been.

In FIG. 1, 1 is an arc tube made of transparent quartz glass, 2 and 2' are electrodes disposed opposite to each other at both ends thereof, 3,
3' is a molybdenum foil that connects each of the current introduction leads 4, 4'.
are connected to each. Inside the arc tube 1, in addition to an appropriate amount of mercury and a rare gas for starting aid, a metal halide evaporates inside the arc tube 1, and these vapors are introduced into a high-temperature, high-pressure mercury arc to emit light. Significantly improves the luminous efficiency and color rendering of the lamp.

The electrode of such a metal halide lung is, for example, a second electrode.
The structure shown in the figure is used. That is, the electrode has a structure in which an inner coil 5 and an outer coil 6 made of a heat-resistant metal such as tungsten are wound, an electrode core wire 7 is inserted into the coil, an electron emitting material 8 is applied, and the electrode is fixed to the coil by heat treatment. there were. Lamps using this type of electrode have excellent luminous flux and long life, but it takes time for the arc spot to stabilize at the time of starting, and the electron emitting material on the electrode surface causes the arc spot to move. There was a drawback that the particles would scatter and adhere to the inner wall of the arc tube.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a discharge lamp electrode that overcomes the drawbacks of conventional discharge lamp electrodes, quickly stabilizes the arc spot at startup, and extends the life of the lamp.

Hereinafter, the discharge lamp electrode of the present invention will be described in more detail with reference to preferred embodiments shown in the accompanying drawings.

FIG. 3 shows an embodiment of the discharge lamp electrode of the present invention. The discharge lamp electrode 10 in this embodiment includes an electrode core wire 11 made of a heat-resistant metal, an inner coil 12 made of at least two layers of tungsten coils wound around the core wire 11, and The coil 13 is wound on the outside and has a wire diameter equal to or larger than the maximum wire diameter of the tungsten used in the inner coil 12.

That is, in the electrode 10, the inner coil 12 is formed by tightly winding the secondary coil wire on the negative coil wire to form a double coil, first winding this double coil as the first layer, and then folding it back. Then, a second layer is further wound on top of that. After inserting the electrode core wire 11 into the inner coil 12 and applying the electron emitting material 14, a coil 13 having a wire diameter equal to or larger than that of the inner coil 12 is inserted into the inner coil 12.
The starting end 15a of the coil 13 is bent in the direction of the core wire 11, and the terminal end 15b is pressed against the core wire 11 to prevent the inner coil 12 from falling off.

The electrode thus manufactured is subjected to heat treatment in vacuum at a predetermined temperature.

The electrode 10 having such a configuration will be explained in more detail.

The double coil used for the inner coil 12 has a diameter of 0.3
A tungsten wire with a diameter of 0.1 m is tightly wound on the primary coil as a secondary coil to form a double coil, and this is wound with 7 turns as the first layer coil and 7 turns as the second layer coil. A tungsten wire having a wire diameter of 0.5 mm, which is larger than the primary coil of the inner coil, is wound around the outer circumference of the inner coil 12 in 10.5 turns. This is inserted into a core wire 11 made of tungsten and having a diameter of 0.9ψ. Electron emitting substances include sosprosium oxide, yttrium oxide,
An electron emitting material made of tungsten powder, nitrocellulose lacquer and butyl acetate was used.

The amount of coating at this time is 6 to 7.
Firing was performed at 200°C for 1 minute.

Using the electrode 10 stirred in this way, an electrode with an inner diameter of 18 IIIl and an arc length of 5
When we manufactured a 400W metal halide lamp with a 0m arc tube and flashed it on and off (15 minutes on, 15 minutes off), the luminous flux maintenance rate after 6000 flashes and dimming was 60%.
%, but in the lamp using the electrode according to the present invention, a result of 70 cm was obtained, and the time for transition from glow to arc was improved from 6 seconds to 1.5 seconds. In this electrode 10, the wire diameter of the outer coil 130 is equal to that of the inner coil 1.
The reason why the wire diameter is set to be the same as or larger than the wire diameter of No. 2 is to quickly release the heat from the inner coil 12 to the outer coil 13.

As explained above, according to the discharge lamp electrode of the present invention, it is possible to prevent the scattering of electron emitting substances at the time of starting, and to heat up the discharge lamp early to form a stable arc spot. It is possible to reduce blackening and provide a lamp with a long life.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the structure of the arc tube of a metal halide lamp, FIG. 2 is a sectional view showing a conventional discharge lamp electrode, and FIG. 3 is a sectional view showing a discharge lamp electrode according to an embodiment of the present invention. be. 10...-discharge lamp electrode, 11... electrode core wire, 12...
- Inner coil, 13... Coil, 14... Electron emitting material. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Shin Kuzuno −

Claims (1)

[Claims] An electrode core wire made of a heat-resistant metal, an inner coil made by winding at least two or more layers of tungsten coils around the electrode core wire, and a tungsten coil wound outside the inner coil and used for the inner coil. An electrode for a discharge lamp that includes a coil with a wire diameter equal to or larger than the largest wire diameter.