JPS61232530A - Manufacture of phosphor screen of color picture tube - Google Patents

Abstract

PURPOSE:To make a phosphor film screen having a good dot form without making a phosphor particle smaller while improving brightness and dispersion by using a phosphor substance with a prescribed amount of pigment adsorbed on its surface. CONSTITUTION:When manufacturing the phosphor screen of a color picture tube, a phosphor substance with 0.5-5.0wt% of adsorbed white pigments on its surface is used. Further, the phosphor screen is manufactured by using slurry in which 0.5-5.0wt% of white pigment is mixed with the phosphor substance slurry composed of the phosphor substance, a light-sensitive agent mainly composed of polyvinyl alcohol and dichromate ammonium and a surface active agent. Thereby, a dot-shaped phosphor film screen is made while improving brightness and dispersion of the picture tube without making a phosphor substance particle smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a phosphor screen for a color picture tube.

(Prior art and its problems) Usually, the phosphor screen of a color picture tube is manufactured as follows. Green, i#, and red phosphors are mixed with a photosensitizer consisting of polyvinyl alcohol (hereinafter abbreviated as PVA) and ammonium dichromate (hereinafter abbreviated as t-ADc), and the phosphors of each color are mixed. Make a body slurry. First, a first color phosphor slurry is applied to the inner surface of the panel, and is optically exposed to light in a predetermined pattern to be cured. Next, the unexposed areas are developed with water to form the first color phosphor in a predetermined pattern. Then, sequentially using other phosphor slurries, 2
The color and third color phosphor patterns are manufactured in the same manner.

When manufacturing a phosphor screen using the above method, it is important that the shape of the phosphor pattern (currently there are two types: stripe type and dotted type, but will be abbreviated as dot in the following explanation) is good.

If the shape of the dots is poor, the phosphor may not be completely filled in the specified position and chipping may occur, or the phosphor may have entered the position of another color, reducing the quality of the color picture tube. This is a major factor in deterioration. In particular, as the demand for high-resolution color picture tubes used for displays increases, its importance is increasing.

Previous attempts to improve the dot shape include improving the dispersibility of the phosphor, examining slurry composition, researching surfactants, and improving the phosphor screen manufacturing process, but none of these methods can be said to be sufficient. . Particularly on the phosphor screen of a high-resolution color picture tube, if the shape of the dots is poor, the quality will be significantly degraded.

In order to improve this drawback, a method has recently been developed in which the size of the phosphor particles is reduced to improve the dot shape. Although this method significantly improved the shape of the cydots,
There are many problems, such as the brightness is lower than that of conventionally used phosphors, and the dispersibility of the phosphor is poor, resulting in more agglomerated defects during coating.

An object of the present invention is to provide a method for manufacturing a phosphor screen that can improve these drawbacks and obtain well-shaped dots. The objective is to produce a phosphor film surface with a good dot shape without reducing the size of the phosphor particles.

(Means for Solving the Problems) As a result of extensive research into the dot shape, the inventor found that the dot shape is based on the light passing through the phosphor film when exposing the phosphor film to create a predetermined dot pattern. It was found that there is a large relationship with the amount of scattering on the surface of the phosphor.

That is, it has been found that even when using phosphor particles of the same size, the dot shape can be improved by mixing fine particles such as titanium oxide into the phosphor film to increase the amount of light scattering.

The present invention involves coating the surface of phosphor particles with light scattering particles, mixing the particles when suspending the phosphor in a photosensitizer (PVA and ADO), or using a combination of the two methods. This method uses a phosphor slurry to create a phosphor screen and improves the shape of the dots.

As an example, when a phosphor screen is manufactured using a phosphor with titanium oxide adsorbed on the surface of the phosphor, the dot shape is significantly improved compared to a phosphor screen manufactured using a conventional phosphor. Ta. Furthermore, the brightness was 98% compared to that using conventional phosphors. This effect is clear when compared with the brightness (90%) of the phosphor particle size reduced to improve the dot shape. Table I shows a comparison of brightness when using a conventional phosphor, a small particle phosphor, and 9 phosphors of the present invention.

Table 1 Brightness Comparison (Green) The second feature obtained by the present invention is that it is superior to the method using small particle phosphors in the process of creating a phosphor slurry and applying it to the face plate of a color picture tube. It has good dispersibility.

Small particle phosphors have the disadvantage that when a certain amount of a slurry prepared from the phosphor and a photosensitizer consisting of PVA and ADC is applied to the inner surface of the panel, the phosphors tend to gather together and cause an agglomerated state. When aggregation occurs, phosphors form clumps, resulting in insufficient light transmission during the exposure process and causing dot drop, which is one of the major drawbacks of color picture tubes, so it is important to reduce the occurrence of aggregation as much as possible. There must be.

In the phosphor film manufactured using the phosphor slurry according to the present invention, the number of agglomerations as described above was extremely reduced. This is thought to be due to the superior dispersibility compared to small particle phosphors, as described above.

Various pigments can be used as the particulate material in the present invention, but white pigments are superior in terms of brightness deterioration and light scattering properties in the fluorescent film. Among them, titanium oxide was most suitable from the viewpoint of stability when made into a slurry and stability when operated as a color picture tube, and a suitable particle size of 0.5 μm or less was found.

The fine particles adsorbed on the surface of the phosphor or mixed into the slurry have a particle size of 0.5 to 5. Qwt% is appropriate. Q,
If it is less than 5 wt%, the light scattering effect during exposure is small, and the effect of improving dot shape is small. In addition, when it exceeds 5.Qwt%, luminance deterioration becomes large.

Examples are shown below.

(Example 1) 1.0 parts by weight of acid-treated gelatin was dissolved in 40°C warm water to prepare a 0.3% gelatin aqueous solution. Zinc sulfide green-emitting phosphor (ZnS:C) was added to this 0.3% gelatin aqueous solution.
uAjLAu ) 100 parts by weight were added and sufficiently uniformly dispersed.

On the other hand, 17 parts by weight of polyvinylpyridone (PVP) was dissolved in warm water to prepare a 0.3% PVP solution. This 0.
2 parts by weight of titanium oxide was added to the 3% PvP solution and dispersed until sufficiently uniform.

Next, the phosphor dispersion and the pigment dispersion were mixed with stirring. The supernatant liquid was removed by decanting, the precipitate was washed repeatedly with water, and the solid content was dried to obtain a green light-emitting phosphor with fine particles.

The blue and red light-emitting phosphors were also treated in the same manner as above to obtain phosphors with fine particles.

After applying a phosphor slurry having the above composition to the inner surface of the panel, it was dried, exposed to 1I light, and developed to form dots of the first color. And then the second color in the same way.

A third color dot was formed.

The dot shape of the phosphor screen thus formed was good.

(Example 2) A phosphor screen was manufactured in the same manner as in Example 1 using the phosphor slurry having the above composition. As in Example 1, the dot shape was good.

(Effects of the Invention) As described above, the present invention is characterized in that a phosphor screen with a good dot shape can be manufactured without making the phosphor particles smaller, and the brightness can be improved by the present invention.

It has many effects such as reduced aggregation due to improved dispersibility.

Claims (2)

[Claims] (1) A method for manufacturing a phosphor screen for a color picture tube, characterized in that the phosphor screen is manufactured using a phosphor in which 0.5 to 5.0 weight percent of a white pigment is adsorbed on the surface of the phosphor. (2) Using a slurry in which 0.5 to 5.0 weight percent of a white pigment is mixed with a phosphor slurry consisting of a phosphor, polyvinyl alcohol, a photosensitizer mainly composed of ammonium dichromate, and a surfactant. A method for manufacturing a phosphor screen for a color picture tube, the method comprising manufacturing a phosphor screen.