JPS6155839A - Manufacture of fluorescent lamp - Google Patents

Abstract

PURPOSE:To extend the life of the phosphor by fixing magnesium hexafluorosilicate to the phosphor surface of a heated glass tube to form a thin magnesium-fluoride film. CONSTITUTION:After a phosphor powder 2 is applied to the inner surface of a glass tube 1, it is placed in an electric furnace 3 and then a spray gun 5 is inserted into the glass tube 1. A carrier gas is sprayed from the spray gun 5 by supplying a constant flow rate of the carrier gas from a gas bomb 6 into the spray gun 5. The temperature of the electric furnace 3 is controlled so that the temperature of the glass tube 1 becomes 500-550 deg.C. An aqueous solution (S) prepared by dissolving magnesium hexafluorosilicate in water is contained in a glass bottle (B). When a valve 9 connected to the bottle (B) is opened, the aqueous solution (S) reaches the spray gun 5 and is atomized there into vapor (K). The vapor (K) then combines with the carrier gas and the mixture is sprayed into the glass tube 1. At the moment the sprayed mixture reaches the phosphor surface of the glass tube 1, the mixture changes into a thin magnesium-fluoride film through thermal decomposition. After that, a fluorescent lamp is completed by a conventional method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a fluorescent lamp, characterized in that a thin film of magsium fluoride is applied to the surface of the phosphor, thereby extending the life of the phosphor.

A1 Purpose and features of the invention The purpose of the invention is to extend the life of fluorescent lamps.

The decrease in luminous flux of a fluorescent lamp is mainly caused by the phosphor coming into contact with plasma and deteriorating its characteristics.

The idea of attaching a protective film to the phosphor to prevent it from coming into direct contact with the discharge plasma has long been known, but during the manufacturing process of the phosphor, the protective material causes an aggregation reaction and the protective film covers the entire surface of the phosphor. The effect of applying the film is significantly reduced because it does not stick and sticks in spots. For this reason, there has been no successful example of this method.

In the present invention, the phosphor was able to be protected from the discharge plasma of the lamp by continuing the work until the protective layer was applied to the entire surface of the phosphor. Herein lies the feature of this invention.

B1 Principle of invention The principle of the invention will be explained.

■ Hexafluoro-magnesium silicate dissolves in water.

■ When heated, this chemical releases crystal water at 150°C, then releases silicon tetrafluoride (gas) at 350°C, and finally precipitates magnesium fluoride (solid).

From this, it is preferable that the temperature of the glass tube at which the hexafluoromagnesium silicate adheres and breaks is 400° C. or higher.

Examples of C9 invention An embodiment will be explained with reference to FIG.

Process: Fluorescent powder 2 is applied to glass tube 1 in advance.

(2) Place this in the electric furnace 3 and insert the spray gun 5 into the glass tube.

(3) A constant flow rate of carrier gas (air, nitrogen, etc.) is sent from the gas cylinder 6 through the regulating valve 7 and the connecting pipe 8 to the spray gun, and the gas is ejected from there. At this time, the electric furnace temperature is controlled so that the glass tube temperature is 500°C to 550°C.

Dissolve magnesium hexafluoro-silicate in water (concentration 5%) and pour this aqueous solution S into glass bottle B. When the valve 9 connected to the bottle is opened, this aqueous solution passes through the valve and the connecting pipe and reaches the spray gun, where it changes into a mist state.

Here, the mist mixes with the carrier gas and is ejected into the glass tube.

[5] The moment the fog reaches the surface of the phosphor on the glass tube wall, it thermally decomposes and turns into a thin film of magnesium heptafluoride. The growth rate of the film can be changed by the height difference H between the spray gun and the aqueous solution S level. In the example, the film growth rate for H-101 was 500 angstroms per minute.

Continue to apply the entire film until the film thickness reaches 5000 angstroms.

(2) Thereafter, the lamp is completed according to the conventional lamp manufacturing method.

D1 Effects of the invention, ii. Recently, the present inventor has devised a set of lamps: (tentative name). Does this device have deterioration characteristics of the phosphor? It is convenient to use when investigating. (Showa 59 Illumination Society of Japan Proceedings P.
12O) Using this apparatus, a deterioration test was conducted on a sample in which a magnesium fluoride thin film was attached to a phosphor to examine the effects of the present invention.

The table below shows the correlation between the brightness of the sample in contact with the deterioration test and the thickness of the thin film attached to the sample. Here, the brightness of the sample before the degradation test without a thin film (film thickness 0 angstroms) was set to 100.
%, and the brightness of each sample deterioration test was expressed as a percentage value with respect to the reference value.

In this specification, all film thicknesses are values determined from mass measurements. Since the film is not expected to adhere uniformly to the sample surface, the values shown here should be considered as average film thicknesses.

Relationship between sample brightness and film thickness after deterioration test Film thickness
0 angstrom bright 60% film thickness
2000 angstroms Brightness 80% Film thickness 3000 angstroms Brightness 90%
Film i 5ooo angstrom Brightness 9
The sample without the 5% magnesium fufluoride protective film (film thickness 0 angstroms) had a brightness of 60% after the deterioration test.
%. On the other hand, in the sample with a film thickness of 5000 angstroms, the reduction in brightness was 95%.

From the above results, it is understood that the present invention is effective in extending the life of a fluorescent lamp.

Effect 2. When we actually made a lamp with a thin film of magnesium heptafluoride (film *5ooo angstroms) attached to the surface of the phosphor and ran a lighting test for 1000 hours, we found that it lasted much longer than a conventional lamp without a thin film. It turned out to be the end of its lifespan.

[Brief explanation of the drawing]

The apparatus used in the embodiment of the invention is shown in FIG. 1... Glass tube for lamp, 2... Fluorescent powder layer, 3...
Electric furnace, °4...Porcelain tube, C...Power source, 5...Mist gun, 6...Gas cylinder, 7...mW valve, 8...Connecting pipe, S
Snout/hexafluoro/magnesium silicate aqueous solution, B...
Bottle, 9... Valve through which the aqueous solution passes,... Mist sprayed out.

Claims (3)

[Claims] (1) The process of coating a glass tube with phosphor powder and then placing it in a heating device (for example, an electric furnace) to heat the glass tube;
F_46H_2O) is attached to the phosphor surface of a heated glass tube, and the hexafluoromagnesium silicate attached to the phosphor surface is thermally decomposed on the glass tube wall to form magnesium fluoride. A method for manufacturing a fluorescent lamp, characterized in that (MgF_2) is precipitated. (2) Claim (1) states that hexafluoro-magnesium silicate is diluted with a solvent, and this diluted liquid is sprayed to adhere the hexafluoro-magnesium silicate to the surface of the phosphor in the glass tube. A method of manufacturing a fluorescent lamp. (3) The method for manufacturing a fluorescent lamp according to claim (1), wherein the glass tube to which hexafluoromagnesium silicate is attached is heated to 400 to 550°C.