JPS60230351A - Low pressure mercury vapor electric-discharge lamp - Google Patents

Abstract

PURPOSE:To reduce the deformation of the coil or blackening of a low pressure mercury vapor electric-discharge lamp by forming the filament by molybdenum doped with at least one element selected from among silicon, aluminum, potassium and nickel. CONSTITUTION:An electrode filament to be used for a fluorescent lamp or a low pressure mercury vapor electric discharge lamp such as a sterilizaton lamp, is formed by kneading a molybdenum oxide powder into a doping material composed of at least one element selected from among silicon, aluminum, potassium and nickel before molding the kneaded mixture into coil-like form. Therefore, it is possible to prevent any deformation of a coil filament which might occur due to decreased shock resistance during long period lighting and to decrease blackening of the ends of the lamp tube. Additionally, it is possible to reduce the cost of the lamp by eliminating the problem of resources without using tungsten.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to low pressure mercury vapor discharge lamps, and more particularly to improvements in the filament thereof.

[Technical background of the invention and its problems]

Conventionally, in low-pressure mercury vapor discharge lamps such as fluorescent lamps and germicidal lamps, electrode filaments sealed at both ends of the bulb are composed of tungsten coils, and emitters are attached to these filaments.

However, tungsten has poor workability in wire drawing and coil forming, and the accompanying annealing treatment is also difficult.
It requires a high temperature of more than 0.degree. C., and for this reason, coil forming requires an expensive molybdenum mandrel, which has a high melting point, so it is unavoidable that it is expensive, and there is also a problem in terms of resources.

Furthermore, since the tungsten filament has a high specific gravity, it is unavoidable that it is heavy, and therefore, when a sudden vibration is applied to the lamp, the emitter attached to the filament may peel off.

Therefore, there are no resource problems compared to tungsten,
It was considered that the filament could be made of molybdenum, which has excellent workability, low annealing temperature, and relatively low specific gravity.

However, low-pressure mercury vapor discharge lamps in which a molybdenum filament is sealed have a drawback that the strength of the coil decreases due to long-term operation, deformation of the coil occurs, and blackening of the end of the lamp tube, resulting in poor commercial value.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-pressure mercury vapor discharge lamp in which a doped molybdenum filament is sealed and the lamp is free from deformation of the coil even after long-term operation.

[Summary of the invention]

The filament is made of molybdenum doped with at least one of silicon, aluminum, potassium, and nickel (all are element names), thereby eliminating deformation of the coil during lighting.

[Embodiments of the invention]

The present inventor doped molybdenum with various substances in order to prevent coil deformation, and constructed the electrode filament of a low-pressure mercury vapor discharge lamp with such doped molybdenum. It was discovered that wall blackening was also improved.

The four doping materials that were effective in preventing coil deformation and improving blackening were silicon, aluminum, potassium, and nickel.
This was the case when an element was used alone or in combination.

Any method known in the art may be used to dope these dopants, but for example, molybdenum oxide may be blended with an appropriate amount of a single substance or an appropriate compound, and then scoured, wire drawn, and coil-formed using a conventional method. The doping elements doped in this way are the same as those present in the molybdenum crystal.
It is thought that they exist at the boundaries of crystal grains, but since it is not clear what kind of chemical structure they have, it is appropriate to express them by element name.

Next, filaments were constructed using molybdenum doped with various doping materials, and their effects were tested. The doping method involves mixing molybdenum oxide powder with a doping material oxide, scouring it, and forming it into a coil.The inspection method is to check the vibration resistance of the coil and to visually check the blackening of the tube end due to long-term lighting of a fluorescent lamp using this coil. It was decided. This darkening determination is based on the following criteria.

A: No discoloration is observed at all.

A' Slight discoloration is observed.

B: Items with partial discoloration.

B' Discoloration is observed throughout.

C: The discoloration is quite significant and the area of discoloration is large.

Judgment was made by selecting the one with the most significant blackening out of each of the three prototypes and judging its degree based on the above criteria.

The results of this judgment are shown in the table below.

As is clear from this table, all of the coils in this test example have high vibration resistance, no coil deformation occurs, and little blackening due to long-term lighting.

Furthermore, since the filament is made of molybdenum, there are no resource problems and it can be manufactured at low cost.

Thus, the present invention can be applied to germicidal lamps as well as fluorescent lamps, and the same effect can be obtained.

〔Effect of the invention〕

The low pressure mercury vapor discharge lamp of the present invention has a filament made of silicon,
Since it is composed of molybdenum doped with at least one element among aluminum, potassium, and nickel,
The sag characteristics of the filament have been improved, the filament has high vibration resistance, and the advantage is that there is less deformation of the filament and less blackening of the lamp due to long-term lighting.

Agent Patent Attorney Inoue - Male

Claims (1)

[Claims] A low-pressure mercury vapor discharge lamp characterized in that a molybdenum filament doped with at least one of silicon, aluminum, potassium, and nickel is sealed.