JPS588551B2 - light bulb - Google Patents

Description

[Detailed description of the invention] The present invention relates to a light bulb with a light-diffusing coating.

Conventionally, silica powder has been applied alone as a coating for light bulbs using an electrostatic coating method.

However, when using silica powder alone, it is necessary to use a silica powder with a high moisture content in order to increase the hiding power of the filament.
This residual moisture in the film causes a so-called water cycle, which has the fatal disadvantage of significantly shortening the life of the light bulb.

Therefore, in recent years, a mixture of alumina powder with a low water content and anhydrous silica, which is easily electrostatically charged, has been considered as a light-diffusing coating.

The purpose of the present invention is to obtain a light-diffusing film for a bulb that has a uniform film distribution, a beautiful film surface, strong adhesion, excellent light distribution, a low luminance ratio, and good filament hiding properties. do.

As a result of researching the relationship between the composition of these components, the average particle size, and the amount of coating, the inventor found that the amount of coating per unit area (m
g/cm2) and the average particle diameter (mμ) of the applied powder is 5.
It has been found that the quality of the coated film, such as the uniformity of the film distribution, the beauty of the film surface, and the adhesion between the glass bulb and the coated film, is good when it is in the range of .about.20.

Furthermore, it has been found that it has excellent light distribution, a low brightness ratio, and excellent filament concealment.

If it is less than the product of both, the filament will have poor hiding properties, a large brightness ratio, and poor light distribution.

If it exceeds 20, the quality of the coating film and the beauty of the film surface will be impaired, and the adhesion between the coating film and the glass bulb will decrease.

Even in the case of a completed ball, there are still drawbacks such as low Lm/W characteristics.

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

400 g of fine alumina powder with an average particle size of 20 mμ and a water content of 3% by weight, 500 g of anhydrous silica powder with an average particle size of 20 mμ and a water content of 0.5% by weight, and 100 g of titanium oxide powder with an average particle size of 100 mμ were mixed and electrostatically Painted on the glass bulb surface.

The average particle size of the mixed powder at that time was 30 mμ.

Figure 1 shows the coating amount m per unit area of the coating film at that time.
g/cm2 to 0. 1mg/cm2 to 0.8mg/
The quality of the coating film and the characteristics of the completed ball were investigated by varying the thickness up to cm2.

All graphs are expressed based on the coating amount per unit area of 0.4 mg/cm (100%).

Curve A shows the hiding power of the filament, and the larger the coating amount, the better.

Curve B shows the Lm/W characteristics of the completed ball, and the smaller the amount of coating, the better.

Curve C shows the adhesion force between the coating film and the glass bulb, and the smaller the amount of coating, the better.

Curve D represents the brightness ratio of the completed ball, and the lower the value, the better the brightness ratio characteristic, and therefore, the larger the amount of coating, the better.

FIG. 2 shows an experiment in which the particle size of the powder was varied from 20 mμ to 40 mμ.

The graph shows the coating amount per unit area of 0.4mg/cm2.
The quality of the coating film and the characteristics of the completed sphere were investigated by keeping the average particle size of the mixed powder constant and varying it from 20 mμ to 40 mμ.

All graphs are based on the average particle size of 30 mμ (100%
).

Similar experiments were conducted by changing the mixing ratio, but as long as the amount of fine alumina powder did not exceed 70%,
The results were similar regardless of the mixing ratio.

Curve E shows the hiding power of the filament, and the larger the average particle diameter, the better.

Curve F shows the Lm/W characteristic of the completed ball, and the smaller the particle size, the better.

Curve G shows the adhesion force between the coating film and the glass bulb, and the smaller the particle size, the greater the adhesion force.

Curve H shows the brightness ratio of the completed sphere, and the larger the average particle diameter, the lower the brightness ratio.

Looking at the characteristics in Figures 1 and 2 together, in order to satisfy both the quality of the coating film and the characteristics of the completed bulb in a light bulb with a diffuser coating, it is necessary to determine the amount of coating per unit area and its mixture. It can be seen that the average particle size of the powder has a large influence.

In experiments conducted by the present inventor, in light bulbs with a light-diffusing coating formed by electrostatically coating the surface of the glass bulb with powder mainly composed of alumina powder and anhydrous silica, the coating film was mixed with the amount applied per unit area. The product with the average particle size of the powder obtained was preferably in the range of 5 to 20, and the best results were obtained when it was 12.

Next, examples will be described.

[Example 1] 400 g of fine alumina powder with an average particle size of 20 mμ and a water content of 3 weight percent, 500 g of anhydrous silica powder with an average particle size of 20 mμ and a water content of 0.5% by weight, and an average particle size of 100 mμ and a water content of 0.5 weight% % titanium oxide powder was mixed and electrostatically deposited on the inner surface of a glass bulb to form a completed sphere.

The average particle size of the mixed powder at that time was 30 mμ, and the coating amount per unit area was 0.4 mg/cm 2 .

In other words, the product was 12.

The quality of the coating film and the properties of the completed ball were very good and still stable.

[Example 2] 400 g of alumina fine powder with an average particle size of 20 mμ and a water content of 3% by weight, 500 g of anhydrous silica powder with an average particle size of 40 mμ and a water content of 0.5% by weight, and an average particle size of 100 mμ and a water content of 0.5 weight% % titanium oxide powder was mixed and electrostatically deposited on the inner surface of a glass bulb to form a completed sphere.

The average particle size of the mixed powder at that time was 40 mμ.

When the amount of coating per unit area is changed, 0. 13
mg/cm2 to 5mg/cm2, that is, the product of both is 5.2
-20, the quality of the coating film and the characteristics of the completed ball were very good and stable.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between coating amount and various properties when the average particle size is 30 mμ, and Figure 2 is a graph showing the relationship between the average particle size and various properties when the coating amount per unit area is 0.4 mg/cm2. It is a graph showing the relationship with characteristics.

Claims (1)

[Claims] 1 A light bulb having a light-diffusing coating made of a mixed powder mainly composed of anhydrous silica and fine alumina powder on the surface of the pulp, the average particle diameter (mμ) of the mixed powder and the coating amount per unit area (mg/ cm2) is 5 to 20.