JPH05307931A - Fluorescent slurry for forming fluorescent screen - Google Patents

Abstract

PURPOSE:To enable the realization of such quality that sufficiently satisfies a fluorescent surface of a high precision color picture tube while corresponding to a fluorescent screen of an ordinary color picture tube by adding a predetermined quantity of polyethylene glycol to a fluorescent dispersant. CONSTITUTION:When 0.03-2.0weight% of polyethylene glycol is added to a fluorescent dispersant mainly consisting of a fluorescent substance, polyvinyl alcohol, and bichromate, the adhesive force of a fluorescent layer is increased. Ultraviolet sensitivity is enhanced, so that the fluorescent layer can be formed with less quantity of exposure than conventional. Accordingly, the film thickness of a fluorescent slurry layer formed by the application of fluorescent slurry is increased so that an adequate fluorescent layer capable of providing high brightness emission with optimum and dense film thickness can be obtained, moreover adhesive force to the inner surface of a panel and capable of providing such fluorescent slurry that less fluorescent particles are remaining on an unexposed portion after development. As the result, a fluorescent surface effective for displaying high quality image required for a high grade color picture tube can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor screen forming phosphor slurry used for forming a phosphor screen of a color picture tube.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 3, a color picture tube has an envelope composed of a panel 1 and a funnel 2 integrally joined to the panel 1, and inside the panel 1, a large number of envelopes are provided. A shadow mask 3 having electron beam passage holes is mounted, and a phosphor screen 4 is formed on the inner surface of the panel 1 so as to face the shadow mask 3. This phosphor screen
4 is blue, green, as shown in FIGS. 4 (a) and (b).
It is composed of dot-shaped or stripe-shaped three-color phosphor layers 5B, 5G, and 5R that emit red light. Meanwhile, the funnel
An electron gun 7 that emits three electron beams 6B, 6G, and 6R is arranged in the neck 6 of 2. Then, the three electron beams 6B, 6G, 6R emitted from the electron gun 7 are deflected by the magnetic field generated by the deflection yoke 8 mounted on the outer side of the funnel 2 to horizontally and vertically scan the phosphor screen 4. , A structure for displaying a color image.

Conventionally, the fluorescent screen 4 of the color picture tube is
It is formed by the photo printing method.

That is, as shown in FIG. 5 (a), a phosphor, polyvinyl alcohol (PVA) and ammonium dichromate (ADC) are the main components, and the PVA and A
By adding multiple kinds of surfactants to the photosensitive liquid consisting of DC,
A phosphor slurry in which the phosphor is uniformly dispersed is applied to the inner surface of the panel 1 and dried to form a phosphor slurry layer 10. Then, as shown in (b), a shadow mask 3 is attached to the inside of the panel 1 on which the phosphor slurry layer 10 is formed, and a mercury lamp or a xenon lamp is attached to the phosphor slurry layer 10 through the shadow mask 3. The phosphor slurry layer 10 is exposed by irradiating ultraviolet rays radiated from the above, and a dot-shaped or striped pattern corresponding to the electron beam passage holes 11 of the shadow mask 3 is printed on the phosphor slurry layer 10. Then, the shadow mask 3 is removed, and as shown in (c), the phosphor slurry layer 10 having the pattern of the electron beam passage holes of the shadow mask burned is developed to remove the unexposed portion, and the unexposed portion is removed. A phosphor layer, for example, a blue phosphor layer 5B is formed. By repeating the method for forming the phosphor layer of any one color for the three-color phosphor, as shown in FIG. 3D, the three-color phosphor layers 5B, 5G, 5R are formed.
A phosphor screen 4 is formed.

The surfactant added to the phosphor slurry has the function of improving the dispersion of the phosphor in the photosensitive liquid and preventing the aggregation. PVA has a function of controlling the thickness of the phosphor slurry layer 10 to be formed and making it uniform as a binder of phosphor particles.

By the way, regarding the phosphor screen 4 of the color picture tube formed by the photo printing method using the phosphor slurry, (a) no phosphor particles remain in the unexposed portion of the phosphor layer after development. (B) The shape of the phosphor layer is sharp. (C) The thickness of the phosphor layer is uniform over the entire phosphor screen. (D) It is desirable that the phosphor particles have a strong adhesive force to the inner surface of the panel. .. Particularly in recent high-definition color picture tubes, the shape of the phosphor layer is smaller than that of the conventional ordinary color picture tube, and in addition to displaying a high-quality image, the demand for the above-mentioned phosphor layer is further increasing.

Generally, when a phosphor screen is formed by a photo printing method, the composition of the phosphor slurry has a great influence on the quality of the phosphor screen. Especially for the fluorescent screen of a high-definition color picture tube, it is possible to form a satisfactory fluorescent screen to some extent even by using a phosphor slurry for forming the fluorescent screen of a conventional ordinary color picture tube. As a high-definition color picture tube for displaying a high-quality image, a phosphor slurry that is still insufficient and can form a better phosphor screen is desired.

[0008]

As described above, the fluorescent screen of the color picture tube has heretofore been formed by using the phosphor slurry by the photographic printing method. In the phosphor screen formed by this photographic printing method, the composition of the phosphor slurry used has a great influence on its quality. Particularly for the fluorescent screen of a high-definition color picture tube, it is possible to form a satisfactory fluorescent screen to some extent even by using the phosphor slurry that has been used for forming the fluorescent screen of a conventional ordinary color picture tube. However, there is a demand for a phosphor slurry that is still insufficient and that can form a better phosphor screen.

The present invention has been made in view of the above problems, and it is possible to form not only the fluorescent surface of a normal color picture tube but also the fluorescent surface of a high-definition color picture tube to a sufficiently satisfactory quality. The purpose is to obtain a phosphor slurry.

[0010]

In a phosphor slurry for forming a phosphor screen, which comprises a phosphor dispersion liquid containing phosphor, polyvinyl alcohol and dichromate as main components, polyethylene glycol is added to the phosphor dispersion liquid. 0.03-
2.0 wt% was added.

[0011]

As described above, 0.03 to 2.0% by weight of polyethylene glycol is added to the phosphor dispersion liquid containing phosphor, polyvinyl alcohol and dichromate as the main components.
When added, the adhesive force of the phosphor layer is increased and the ultraviolet sensitivity is increased, so that the phosphor layer can be formed with a smaller exposure amount than before. As a result, by increasing the film thickness of the phosphor slurry layer formed by applying the phosphor slurry, it is possible to obtain an optimal and dense phosphor layer capable of obtaining high-luminance emission,
In addition, it is possible to obtain a phosphor slurry which has a strong adhesive force to the inner surface of the panel and has less phosphor particles remaining in the unexposed portion after development.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

Any one of the blue light emitting phosphors ZnS: Ag, Cl, the green light emitting phosphors ZnS: Cu, Al, Au, the red light emitting phosphor Y ₂ O ₂ S: Eu, PVA and A.
0.5% by weight of polyethylene glycol (PEG) was added to the conventional phosphor slurry (phosphor dispersion liquid) containing DC as a main component and plural kinds of surfactants added thereto, and 2.0% by weight.
Wt% and 5.0 wt% are added and uniformly mixed and dispersed to prepare a phosphor slurry, and the phosphor slurry is applied to the inner surface of the panel to form a phosphor slurry layer. Similarly, a dot-shaped phosphor layer was formed by a photographic printing method and evaluated.

FIG. 1 shows the amount of exposure when the pattern of the electron beam passage hole of the shadow mask is printed on the phosphor slurry layer of the green light emitting phosphor ZnS: Cu, Al, Au formed by coating on the inner surface of the panel. 2 shows the relationship with the size of the dots (phosphor layer). In this FIG.
The curve 20 is a conventional phosphor slurry containing no PEG added for comparison, and the curve 21 is a phosphor slurry obtained by adding P to the phosphor slurry.
The phosphor slurry with 0.5% EG added, curve 22,
Similarly, a phosphor slurry with 2.0% by weight added, curve 23,
Similarly, it is the relationship between the exposure amount of the phosphor slurry added with 5.0% by weight and the size of the dot.

As can be seen from the comparison between the conventional phosphor slurry curve 20 and the PEG-added phosphor slurry curves 21, 22, 23, the addition of PEG gives the same exposure as compared to the case without PEG. The dot becomes larger in amount, and becomes larger as the amount of PEG added increases. This is because the ultraviolet curing sensitivity when baking the pattern of the electron beam passage holes of the shadow mask increases as the amount of PEG added increases.

In the figure, the region surrounded by points a, b, c and d is the permissible range of the phosphor particles remaining in the unexposed portion after the development when forming the phosphor screen, and within this permissible range. When the dots are formed by, the color mixture that occurs due to the remaining phosphor particles being mixed with the dots of other colors causes almost no problem. From this, the phosphor slurry in which 5.0 wt% PEG of curve 23 is added has a large amount of phosphor remaining in the unexposed portion and is not suitable for forming the phosphor screen of the color picture tube.

Further, in the phosphor slurry containing PEG, for example, the phosphor slurry containing 0.5% by weight of PEG, the sharpness of the same shape with respect to the curve 21 is within the range of 50 to 95% of the exposure amount. It was possible to form various dots.

FIG. 2 shows the relationship between the dot size and the adhesive force. Curve 25 is a conventional green light emitting phosphor ZnS: Cu, Al, Au with no PEG added for comparison.
Curve 26 for the phosphor slurry of 0.5
The phosphor slurry added by weight%, curve 27 is 2.0
It is the relationship between the dot size of the phosphor slurry added by weight% and the adhesive force. Regarding the relationship between the dot size and the adhesive force, the fluorescent substance slurry layer was exposed through filters having different transmittances, and after development, the adhesive force was evaluated by the residual ratio of the dots remaining in a certain area.

As can be seen from FIG. 2, the adhesive force of dots increases as the amount of PEG added increases.

Table 1 also shows a phosphor slurry of a conventional green light-emitting phosphor ZnS: Cu, Al, Au which does not contain PEG, a phosphor slurry obtained by adding 0.5% by weight of PEG to the phosphor slurry, and also PEG. The following shows the luminance at the four corners of each phosphor screen (average value at the four corners) when a phosphor screen made of a dot-shaped phosphor layer is formed using a phosphor slurry containing 2.0 wt% of. The brightness is shown as a relative value with respect to the brightness of the phosphor screen formed by the conventional phosphor slurry without the addition of PEG.

[0021]

[Table 1] As can be seen from Table 1, when PEG is added to the phosphor slurry, the brightness is improved with the increase of the addition amount. This is presumably because the addition of PEG increases the adhesive force of the dots, resulting in thick dots at the four corners of the phosphor screen.

As described above, PEG is added to the conventional phosphor slurry.
Although the experiment of adding 5 to 5.0% by weight was explained, the addition amount of PEG to this phosphor slurry was 0.03 to
The same effect can be obtained in the range of 2.0% by weight.

In the above embodiment, the green light emitting phosphor Zn
Although the phosphor slurries of S: Cu, Al and Au have been described, similar results can be obtained as a result of the experiment with the blue light emitting phosphors ZnS: Ag and Cl and the red light emitting phosphor Y ₂ O ₂ S: Eu. It was

[0024]

EFFECT OF THE INVENTION PEG is added in an amount of 0.03% to a phosphor slurry containing phosphor, PVA and dichromate as main components.
When 2.0 wt% is added, the adhesion of the phosphor layer to the inner surface of the panel is increased, the ultraviolet curing sensitivity is increased, and the phosphor layer can be formed with a smaller exposure amount than before. As a result, the thickness of the phosphor slurry layer formed by applying the phosphor slurry is increased to obtain an optimum and dense phosphor layer capable of obtaining high-luminance emission, and to the inner surface of the panel. It is possible to form a fluorescent screen effective for displaying a high-quality image desired for a high-definition color picture tube, such as a strong adhesive force and a small amount of phosphor particles remaining in an unexposed portion after development.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an exposure amount and a size of a dot formed by a phosphor slurry which is an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between dot size and adhesive force.

FIG. 3 is a diagram showing a configuration of a color picture tube.

FIG. 4 (a) is a diagram showing a structure of a phosphor screen composed of dot-shaped phosphor layers of a color picture tube, and FIG. 4 (b) is a structure of a phosphor screen composed of striped phosphor layers. It is a figure.

5A to 5D are views for explaining a phosphor screen forming method of a color picture tube.

Claims (1)

[Claims] 1. A phosphor screen comprising 0.03 to 2.0% by weight of polyethylene glycol added to a phosphor dispersion liquid containing phosphor, polyvinyl alcohol and dichromate as main components. Forming phosphor slurry.