JPS6216492B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing instant-light fluorescent lamps.

Conventionally, in instant-light fluorescent lamps that have a transparent conductive film formed on the inner surface of the bulb, a discharge occurs between the discharge space and the conductive film during lighting, which destroys the phosphor and causes it to turn black and deteriorate its appearance. The top looks very unsightly.

As a countermeasure against this problem, the following method is conventionally known.

(1) A method to facilitate discharge by depositing a thin layer of phosphor.

(2) A method in which an electrical insulating layer is interposed between the conductive film and the phosphor to prevent discharge from occurring.

In method (1) above, the thickness of the phosphor layer becomes thinner, resulting in a darker lamp. Furthermore, in the method (2) above, the brightness of the lamp decreases, and in addition, an extra step of forming an electrically insulating layer is required, which complicates the manufacturing process.

Therefore, in order to eliminate such drawbacks of the prior art, the present inventor considered protecting the surface of the phosphor coating with a heat-resistant metal oxide film. A conceivable method for this is to apply a mixed suspension of phosphor particles and heat-resistant metallized fine particles such as alumina sol to the conductive film of the bulb. The phosphor coating obtained by this method has heat-resistant metal oxide fine particles interposed between the phosphor particles, and is easy to manufacture. However, on the other hand, the coating of the fluorescent particles is not complete, some of the surfaces of some of the fluorescent particles are exposed to the discharge space, some of the fluorescent particles are in direct contact with the surface of the conductive film, and Some of the phosphors are in direct contact with other phosphor particles without intervening heat-resistant metal oxide fine particles.

In this way, the phosphor coating coated by adding heat-resistant metal oxide fine particles to the phosphor particles cannot prevent discharge along the surface of the phosphor particles because the phosphor particles are incompletely covered. First, if a discharge occurs between the discharge space and the conductive film, it is not possible to completely prevent the phosphor coating from becoming black.

The present invention was made based on the above-mentioned circumstances, and the surface of the phosphor particles is coated in advance with a heat-resistant metal oxide, and the coated phosphor particles are adhered to a conductive film. By forming a phosphor coating, all the phosphor particles are individually coated with a heat-resistant metal oxide, eliminating the exposed surface of the phosphor;
This prevents the phosphor from becoming black even if a discharge occurs along the surface of the phosphor particles.

Hereinafter, the details of the present invention will be explained with reference to Examples. First, an example of an instant lighting type fluorescent lamp obtained by the method of the present invention will be outlined with reference to FIGS. 1 and 2. 1 is a straight glass bulb, 2 is a transparent conductive film formed on the inner surface of the bulb 1, 3 is a phosphor coating formed on the conductive film 2, and 4 is sealed at both ends of the bulb 1. It is a filament. As schematically shown in FIG. 2, the phosphor coating 3 is formed by stacking heat-resistant metal oxide particles 6 on the surfaces of phosphor particles 5. The heat-resistant metal oxide fine particles 6 are heat-resistant and non-conductive, and are resistant to electric shock, and are made of at least one of alumina, titania, antimony oxide, silica, tin oxide, etc., all of which have an average particle size. The diameter is 1μ or less.

Next, an example of a method for manufacturing this lamp will be explained. First, fine alumina particles having, for example, an average particle size of 0.5 μm are mixed with the phosphor particles 5, ethyl alcohol is added thereto, and after thorough stirring, the alcohol is evaporated. The phosphor particles 5 thus obtained have their surfaces covered with alumina fine particles 6 as described above.
covered with. Using this phosphor powder coated with alumina fine particles, the first
The instant lighting type fluorescent lamp shown in the figure is constructed.

As mentioned above, the phosphor particles 5 in alcohol
The reason why the alumina particles 6 are firmly adhered to the surface of the phosphor particles 5 simply by stirring the alumina particles 6 is not well understood, but it is probably because alcohol is a polar solvent and the alumina particles 6
Because it consists of fine particles with an average particle size of about 0.5μ,
It is presumed that the phosphor particles 5 and the alumina fine particles 6 are slightly charged and are electrostatically bonded to each other. The reason why ethyl alcohol is particularly used is that it has appropriate polarity and has the advantage of rapid evaporation. Care must be taken in selecting the solvent; for example, if an aqueous mineral acid solution is used, the solvent will be concentrated during the evaporation process and become strongly acidic, which will attack the phosphor and reduce luminous efficiency.

As described above, according to the present manufacturing method, the surfaces of the phosphor particles 5 are coated with alumina fine particles 6 in advance, and then the coated phosphor particles 5 are coated with the conductive film 2.
Because of the over-deposition, all phosphor particles 5 are uniformly coated with alumina particles 6, with no exposed surface of any phosphor particle 5. Therefore, when a discharge occurs between the discharge space and the conductive film 2 through the phosphor coating obtained in this way, even if the discharge occurs along the surface of the phosphor particles 5, this Since the surface of the particles 5 is protected by the heat-resistant metal oxide 6, the phosphor particles 5 themselves are not damaged or discolored by the heat of the discharge. Therefore, there is no risk of this lamp turning black even if it is lit for a long period of time.

Next, the effects of the instant lighting type fluorescent lamp obtained by the method of the present invention will be explained using experimental examples. The phosphors used in the experiment were all calcium halophosphate phosphors, and the heat-resistant metal oxides were (A) fine alumina particles with an average particle size of 0.5 μm, (B) fine titania particles with an average particle size of 0.5 μm, and (C) fine particles of titania with an average particle size of 0.5 μm. Average particle size
Antimony oxide fine particles of 0.5μ were used.

First, we investigated the incidence of blackening of the phosphor due to long-term lighting and compared it with conventional ones. This result is the fifth
As shown in the figure. In the figure, the horizontal axis shows the lighting time in units of x10 ³ hr, and the vertical axis shows the incidence of blackening of the phosphor in units of % on an inverted scale.Curve _A4 shows the proportion of alumina fine particles mentioned above. In other words, [weight of alumina ÷
(fluorescent weight + alumina weight)] is 5% by weight, curve B ₄ is for the case where the proportion of titania fine particles mentioned above (same weight % as for alumina) is 5% by weight, and curve D ₂ is for Curve _E2 shows the blackening characteristics of a conventional conductive film that does not use any heat-resistant metal oxide, and a conventional conductive film that is coated with alumina powder to a thickness of 50 to 100μ, and then coated with a phosphor. shows. This figure proves the superiority of the present invention,
In particular, it can be seen that the one with an alumina content of 5% by weight is excellent.

Next, we investigated the luminous flux maintenance rate with long-term lighting.
compared with the conventional one. The results are shown in FIG. In the figure, the horizontal axis shows the lighting time in units of x10 ³ hr.
The vertical axis shows the luminous flux maintenance rate in units of %, with the initial lighting period being 100. Curve A ₂ is for the alumina particles with a proportion of 5% by weight, and curve A ₃ is for the alumina particles with a proportion of 10% by weight. Curve B ₂ is for the proportion of titania fine particles mentioned above, which is 5 weight percent, and curve B ₃ is for the proportion of titania fine particles mentioned above, which is 5 weight percent.
10% by weight, curve D ₁ is a conventional heat-resistant metal oxide that is not used at all, and curve E ₁ is a conventional conductive film coated with alumina fine particles to a thickness of 50 to 100 μm, and then a phosphor is applied on top of it. The luminous flux maintenance characteristics of each coating are shown below. This figure proves the superiority of the present invention, and it can be seen that the alumina content of 5% by weight is particularly excellent.

Furthermore, the proportion of heat-resistant metal oxide, that is, as in the case of alumina mentioned above, [oxide weight ÷
(fluorescent weight + oxide weight)] and the total luminous flux was investigated. The results are shown in FIG. In the figure, the horizontal axis shows the proportion of heat-resistant metal oxide in weight percent, and the vertical axis shows the total luminous flux in arbitrary units. Curve _A1 is the one using the above-mentioned alumina fine particles, and curve B is the one using the above-mentioned alumina fine particles. ₁ shows the correlation curve using the above-mentioned titania fine particles, and curve _C1 shows the correlation curve using the above-mentioned antimony oxide fine particles. From this figure, when titania fine particles and antimony oxide fine particles are used, the total luminous flux is particularly good in the range of 3 to 15% by weight compared to when using other weight%, and when alumina fine particles are used, It can be seen that the total luminous flux is particularly good in the range of 3 to 10% by weight compared to other percentages.

As described above, the method for manufacturing an instant-lighting type fluorescent lamp of the present invention includes the step of depositing phosphor particles on the conductive film formed on the inner surface of the bulb to form a phosphor coating. Since the surface of the phosphor is coated with a heat-resistant metal oxide in advance and then deposited on the conductive film, all the phosphor particles are uniformly coated with the heat-resistant metal oxide and the phosphor is exposed. As a result, the phosphor surface is protected by a heat-resistant metal oxide, so even if a discharge occurs between the discharge space and the conductive film, the phosphor will not darken. Therefore, a lamp that is bright enough to avoid blackening during its life can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the instant lighting type fluorescent lamp of the present invention, FIG. 2 is an enlarged schematic diagram of the phosphor particles, and FIG. 3 is a diagram showing the proportion of heat-resistant metal oxide in the present invention. Figure 4 is a graph showing that the lamp of the present invention is superior in luminous flux maintenance rate; Figure 5 is a graph showing that the lamp of the present invention is superior in the incidence of blackening of the phosphor. It is a graph. DESCRIPTION OF SYMBOLS 1... Bulb, 2... Conductive film, 3... Phosphor coating,
5... Phosphor particles, 6... Heat-resistant metal oxide fine particles.

Claims (1)

[Scope of Claims] 1. In the process of depositing phosphor particles on a conductive film formed on the inner surface of a bulb to form a phosphor film, the surface of the phosphor particles is coated with a heat-resistant metal oxide in advance. 1. A method for producing an instant-light fluorescent lamp, which comprises coating the conductive film with a material and then depositing it on the conductive film. 2. Claim 1, characterized in that the phosphor particles are stirred together with heat-resistant metal oxide fine particles in a polar solvent so that the heat-resistant metal oxide fine particles adhere to and coat the surface of the phosphor. A method for manufacturing an instant-lighting fluorescent lamp as described in 2.