JPS59180950A - Metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To maintain the electron emitting substance without exfoliation or drop out by making coarse winding at the arc side part of an inside coil constituting a main electrode and close winding at other part, and by forming an outer coil over the inside coil by rewinding the inside coil and making close winding to cover the coarse winding part of the inside coil. CONSTITUTION:In order to form a main electrode of a metal halide lamp, using a thoriated tungsten bar of diameter 0.8mm. as an electrode core wire 8 and also a tungsten wire of diameter 0.6mm. as inside and outside coils 9, 10, an inside coil 9 is wound 4 turns with coarse winding and 3 turns with close winding, and moreover an outer coil 10 is rewound around the coil 9 and wound 8 turns to cover coarse winding part entirely. Then, one part of a core wire 8 is inserted into the coil, and after filling electron emitting substance 11 within gaps of the coil 9 etc. the core wire 8 is inserted to a predetermined position. The above mentioned electrode is heat-treated at high temperature within inert gas atmosphere, and the emitting substance 11 is stuck to and held by the electrode. By using such an electode, starting characteristics and flux maintenance rate of a lamp with remaining service life can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to high-pressure vapor discharge lamps such as mercury lamps, high-pressure sodium lamps, metalnolide lamps, etc., and particularly improves the electrode structure and life characteristics.

This will be explained below using a metal halide lamp as an example.

The arc tube of a metal halide lamp is generally constructed as shown in FIG. That is, an appropriate amount of a starting rare gas such as a mixed gas of mercury, metal halide, and neon-argon is sealed inside the transparent arc tube (1) made of quartz glass, and main electrodes ( 2a), (2b)
are installed facing each other and are connected to conducting wires (6a) and (6b), respectively, via molybdenum foils (4a) and (4b) attached to both ends of one arc tube (1). At least one end also has an auxiliary electrode (
3) is provided, and a conducting wire (7) is provided through the molybdenum foil (5).
)It is connected to the. Then, the main electrode (2a), (
2b) has a configuration as shown in FIG. 2, for example,
An inner coil (9) and an outer coil qQ made of a heat-resistant metal such as tungsten are wound around an electrode core wire (8) made of a heat-resistant metal such as tungsten. The inner coil is loosely wound, and the gap is filled with an electron emitting material.

As the electron emitting substance, sodium chloride or scandium oxide is usually used.

Although these oxides have excellent heat resistance, they have weak adhesion to the electrodes, and may peel off from the electrodes due to thermal cycles during their life.
It was easy to fall off. the result.

It becomes difficult to maintain stable electron emission from the electrode during its lifetime, resulting in an increase in starting voltage and a decrease in luminous flux maintenance factor.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and the inner coil consists of a coarsely wound part and a tightly wound part, and the coarsely wound part is arranged on the arc side part of the electrode core wire. , a discharge lamp in which the outer coil is formed by unwinding the inner coil, and by using a closely wound coil that covers at least the loosely wound portion of the inner coil, the starting characteristics and luminous flux maintenance rate of the lamp are significantly improved during the lamp's life. The present invention provides electrodes for use in

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows an example of the electrode structure of a metal halide lamp according to the present invention. The electrode component was constructed by using a triated tungsten rod with a diameter of 08 mm as the electrode core wire (8), -1 (inner and outer coils +9) and a Betungsten wire with a diameter of 06 mm as QQ.

Wind the inner coil (9) roughly for 4 turns and tightly for 3 turns. Then, wind the outer coil αQ back to 1 wa υ of the inner coil (9) and wind it for 8 turns so that it covers all the coarsely wound parts. Make it. After that, a part of the electrode core wire (8) is inserted into the coil, and an electron emitting material α made of scandium oxide is inserted into the coil.
After filling the gap of the inner coil (9) etc. with υ, the electrode core wire (8) is inserted at a predetermined position 1.

The above electrode is subjected to high temperature heat treatment in an inert gas atmosphere,
Electron emitting material αυ is fixedly held on the electrode.

The electrode containing the electron radioactive material produced in this way (
2a) and (2b), an appropriate amount of scandium (S.), mercury iodide (H,■,), sodium iodide (NaI), mercury (H6) and neon-argon gas (argon 05%) inner diameter 20mm,
Arc length 45. A 400W metal halide lamp was created by forming an arc tube (1) of , and placing this arc tube inside an outer tube filled with neon-nitrogen gas (No-N2), which was lit for 5 hours and then for 1 hour. Rated lighting 6 with test cycle of lights off
The lamp starting voltage and luminous flux maintenance factor were measured after 000 hours. For comparison, an electrode having the conventional structure shown in FIG. 2 was prepared as follows. That is, the electrode core wire (8) has a diameter of 0.
Using 0.6 mm diameter tungsten wire as the inner and outer coils (9) and QO), the inner coil (9) was roughly wound for 4 turns. The inner coil (9) is unwound and the outer coil 00) is wound with 8 turns to the same size as the inner coil (9). Thereafter, a part of the electrode core wire (8) is inserted into the coil, and after filling the gaps such as the inner coil (9) with the electron radioactive substance αυ, the electrode core wire (8) is inserted at a predetermined position 1. This electrode is heated at high temperature in an inert gas atmosphere,
The electron emitting material αυ was fixed and fabricated.

A 400 W metal halide lamp was prepared using the electrode thus prepared with the other components being the same as those described above, and the luminous flux maintenance factor was measured under the same test conditions.

Table 1 shows the measurement results.

Table 1 As is clear from Table 1, when the electrode according to the present invention is used, the increase in lamp starting voltage after 6000 hours is less than when the conventional electrode is used. It can be seen that the luminous flux maintenance rate is significantly lower than that of the conventional method. The cause of such a difference in characteristics is thought to be as follows.

That is, in conventional electrodes, scandium oxide with an electron emitting substance of 0υ has excellent heat resistance.

It has weak adhesion to electrodes, and therefore is prone to peeling and falling off due to thermal cycles during its life, making it difficult to maintain stable electron emission. On the other hand, the electrode according to the present invention prevents the electron emitting material υ from peeling off or falling off from the electrode by providing a tightly wound part on the inner coil (9), thereby maintaining stable electron emission throughout its life. As a result, the starting characteristics and luminous flux maintenance rate during the service life are significantly improved.

In the above embodiments, a metal halide lamp containing scandium iodide and sodium iodide was explained.
However, similar effects can be obtained with metal halide lamps containing other metal halides, mercury lamps, and high-pressure sodium lamps. It is clear that the effects of the present invention can be obtained even when atomic emitting substances other than scandium oxide are used.

As explained above, the inner coil consists of a coarsely wound part and a tightly wound part, the coarsely wound part is formed on the arc side part of the electrode core wire, and the outer coil is formed by unwinding the inner coil, and at least By using a tightly wound coil that covers the loosely wound portion of the coil, it has the effect of significantly improving the starting characteristics and luminous flux maintenance rate of the lamp during its life.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the configuration of an arc tube of a metal halide lamp, FIG. 2 is an enlarged sectional view showing the structure of a conventional electrode, and FIG. 3 is an enlarged sectional view of an electrode showing an embodiment of the present invention. . In the figure, (1) is a translucent arc tube, (2a), (
2b) is the main electrode, (3) is the auxiliary electrode, (8) is the electrode core wire, (9) is the inner coil, and a (outer coil) 211) is the electron emitting material. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Makoto Kuzuno

Claims (1)

[Claims] In a metal vapor discharge lamp in which at least a starting rare gas and mercury are sealed in an arc tube having a pair of main electrodes, the main electrode is wound around an electrode core wire and the arc side The inner coil is roughly wound and the opposite side is tightly wound, and the inner coil is unwound and wound around the inner coil, and the outer coil is tightly wound to cover at least the coarsely wound part of the inner coil. A metal vapor discharge lamp comprising an electron emitting material held between an electrode core wire and an outer coil.