JPH06176735A - Electrode for fluorescent lamp - Google Patents

Abstract

PURPOSE:To provide an electrode which can hold a large quantity of effective electron emitting material with the simple structure. CONSTITUTION:The electron emitting material 3 is obtained by mixing one kind or more of the thermal conductivity type high melting point porcelain powder such as beryllia and alumina for improving the thermal conductivity and the reduction type high melting point metal powder such as tantalum, niobium, tungsten, and molybdenum for reducing the natural resistance and accelerating the reduction of barium oxide with the compound carbonate of alkaline earth metal, which includes several weight% of conventional zirconium oxide. This material 3 is filled in the multiplex winding type coil filament 1 till the final winding part thereof is filled with the material 3 to hold a large quantity of electron emitting material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp electrode.

[0002]

2. Description of the Related Art Generally, the life of a fluorescent lamp is determined by the fact that the electron emissive material filled in the primary coil of a tungsten multi-coil filament is scattered, evaporated and consumed at the time of starting and operating the lamp.

As the multi-coil filament, a double-coil filament, a so-called triple-coil filament in which a thin wire is loosely wound around the double-coil filament, or a block-coil filament in which a coil is triple-coiled, has been put into practical use.

Conventionally, a complex oxide of an alkaline earth metal (barium, strontium, calcium) containing a few wt% of zirconium oxide has been used as an electron-emitting substance. As a result of various improvements in recent years, for example, FL1
The average life of 0 is 5,000 hours, the FL20S is 7,500 hours, and the FL40S and FLR40S are 10,000 hours.

[0005]

However, from the viewpoint of resource saving and environmental pollution (emission of mercury contained in the lamp tube) in recent years when global environmental problems are becoming apparent, the average life of the above fluorescent lamp is , I can't say that I have reached a satisfactory level.

The simplest means for extending the average life of fluorescent lamps is to increase the amount of electron emissive material applied to the multi-coil filament.

However, since the conventional electron emissive material has a large specific resistance and poor heat conduction, when the amount of deposition on the multi-coil filament is increased, thermal decomposition by heating the electron emissive material during production of the lamp (carbonate (The process of changing to oxide) tends to be inadequate, and as a result undecomposed electron emissive material remains in the tube, adversely affecting the electron emission of the electrode and releasing impure gas, blackening the tube wall, lowering the luminous flux, etc. Cause a short life, and the quality of the fluorescent lamp is significantly deteriorated.

Barium oxide, which contributes most to electron emission, is reduced to tungsten, which is the base material of the multi-coil filament, to form free barium, which lowers the work function, but the thickness of the electron emissive substance which is reduced by diffusion. It is said that the maximum is about several tens of μm from the base material, and even if the thickness of the electron emissive substance is increased for the purpose of increasing the deposition amount, most of the electron emissive substance is not effectively used, and therefore the life is not extended.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a long-life fluorescent lamp electrode capable of holding a large amount of an effective electron-emitting substance with a simple structure. is there.

[0010]

In order to solve the above problems, the present invention provides a conventional alkaline earth metal complex carbonate containing several wt% of zirconium oxide, boron nitride and beryllia in order to improve heat conduction. , A mixture of thermally conductive refractory porcelain powder such as alumina and one or more reducing refractory metal powders such as tantalum, niobium, tungsten and molybdenum to reduce the resistivity and promote the reduction of barium oxide. It is characterized in that the electron emitting substance is filled up to the final winding portion of the multi-coil filament.

[0011]

According to the present invention, porcelains such as boron nitride, beryllia and alumina have high thermal conductivity, and tantalum, niobium,
Metals such as tungsten and molybdenum have high reducing properties,
In addition, since the electric resistivity is low, the characteristics of the electron-emitting substance can be greatly improved by mixing it with a conventional alkaline earth metal complex carbonate containing several wt% of zirconium oxide.

That is, even if an electron emissive material is filled in a position apart from tungsten, which is a base material of the multi-coil filament, the porcelain powder has a high thermal conductivity and the metal powder has a low electric resistivity, so that the lamp can be manufactured. At that time, the thermal decomposition of the electron emissive substance by the energization is surely performed, and the desired alkaline earth metal composite oxide is obtained.

Further, regardless of the filling place, since the reducing metal exists in a good heat conducting state around barium oxide,
Free barium is always produced in good condition without any restriction on the thickness of the tungsten filament of the substrate. Further, since the porcelain powder and the metal powder have high melting points themselves, they are also resistant to sputtering due to ion bombardment when the lamp is turned on.

[0014]

EXAMPLES The present invention will be described in detail below based on examples.

FIG. 1 shows an embodiment of an electrode for a fluorescent lamp according to the present invention. In the figure, 1 is a multiple coil filament wound with a tungsten wire, for example, a double coil filament, both ends of which are introduced. It is pinched to lines 2 and 2. 3 is an electron emissive material having the following composition, and is filled up to the final winding portion of the multi-coil filament 1 as shown in the drawing.

Barium carbonate: 29 wt% Strontium carbonate: 27 wt% Calcium carbonate: 15 wt% Zirconium oxide: 9 wt% Boron nitride powder: 5 wt% Metal tantalum powder: 15 wt% Above 3 types The above-mentioned carbonates are not used alone, but are used in the form of complex carbonates synthesized so as to have the described weight ratio.

The particle diameters of the boron nitride powder and the metal tantalum powder to be mixed are preferably equal to or smaller than the average particle diameter of the composite carbonate in consideration of the adhesion force to the coil filament. The diameter was set to 2 to 3 μm for the diameter of about 5 μm.

The above mixture was mixed with 5% by weight of nitrocellulose.
The multi-coil filament 1 was suspended in a butyl acetate solution containing the same and filled up to the final winding portion of the multi-coil filament 1 to be applied. After that, a ramping process was performed in the same manufacturing process as the conventional one.

According to the present embodiment, the retained amount of the electron emissive substance 3 is about 5 times as effective (barium carbonate and strontium carbonate equivalent) as the amount of the conventional multi-coil filament filled with the primary coil. was gotten. Further, the thermal conductivity of the electron emissive material 3 was increased by 4 to 6 times by mixing with boron nitride, and there was no adverse effect on the pre-heat starting performance of the lamp. Furthermore, by reducing the average particle size of the boron nitride powder and the tantalum metal powder, the vibration test results showed that the electron emissive material 3 did not drop off significantly.
It was confirmed that there was no problem in practical use.

Next, regarding the life test of the fluorescent lamp provided with the electrode according to this embodiment, various fluorescent lamps having different wattages were experimentally manufactured and tested, and as a result, it was three times or more compared with the conventional fluorescent lamp. A lamp with a lighting life was obtained.

The amount of boron nitride mixed is 3 to.
A range of 10 wt% showed good results as a heat conductive material. Further, as the heat conductive high melting point porcelain powder, beryllia,
The same effect was obtained when alumina or the like was mixed. Regarding the mixing amount of the metal tantalum powder, it was found that the reduction of barium oxide was insufficient when the content was 3 wt% or less, and the reduction of barium oxide was excessive when the content was 25 wt% or more, resulting in remarkable blackening of the tube wall. . Therefore, the amount of the metal tantalum powder mixed is preferably 5 to 20 wt%.

Further, when the reducing refractory metal powder was mixed with niobium, tungsten, molybdenum, etc., good results equivalent to those of metal tantalum were obtained. further,
You may mix and use 2 or more types of metal powder as needed. In this case, the total mixing amount is 5 wt% or more, 20 wt%
The following is desirable.

[0023]

As described above, according to the present invention, a composite carbonate of an alkaline earth metal containing zirconium oxide of several wt% is added to a thermally conductive high melting point porcelain powder such as boron nitride, beryllia or alumina, and tantalum or niobium. By filling up the final winding part of the multi-coil filament with an electron emissive material that is a mixture of one or more reducing refractory metal powders such as tungsten, molybdenum, etc., the filament electrode can hold a large amount of electron emissive material. It has been possible to provide an electrode capable of obtaining a fluorescent lamp having an extremely long life, which is three times or more that of the conventional one.

Further, since it is only necessary to mix the porcelain powder and the metal powder with the conventional electron emissive material and to fill up to the final winding portion of the multi-coil filament, it is possible to manufacture with existing equipment without any special equipment. Therefore, mass production is easy and there is no factor of cost increase.

Further, according to the present invention, since the specifications of the multi-coil filament (double coil filament, triple coil filament, block coil filament, etc.) can be exactly the same as the conventional ones, the electrode according to the present invention is used. The fluorescent lamp remains fully compatible with conventional fluorescent lamps. Therefore, it is possible to extend the life of the existing lighting fixture simply by mounting the fluorescent lamp using the electrode according to the present invention.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view showing an embodiment of the present invention.

[Explanation of symbols]

 1 multi-coil filament 2 lead-in wire 3 emissive material

Claims (1)

[Claims] 1. A composite carbonate of an alkaline earth metal containing several wt% of zirconium oxide, 3 to 10 wt% of thermally conductive high melting point porcelain powder such as boron nitride, beryllia, and alumina, tantalum, niobium, and tungsten. An electrode for a fluorescent lamp, characterized in that an electron emissive material obtained by mixing 5 to 20 wt% of one or more reducing refractory metal powders such as molybdenum is filled up to the final winding part of a multi-coil filament.