JPS6276133A - Formation of fluorescent screen for color picture tube - Google Patents

Abstract

PURPOSE:To form images with good white uniformity by restricting the ratio between the weight of the solid PVA component and the weight of a phosphor in a slurry to be applied to the inner surface of a panel according to the effective sedimentation time of the phosphor in the slurry. CONSTITUTION:When the ratio between the weigh of the solid photosensitive resin component and the weight of a phosphor in a slurry is supposed to be A and the effective sedimentation time of the phosphor is supposed to be x seconds, a first, a second and a third color slurry are prepared according to the formulae 0.08x+1.5<=A<=0.08x+3.5, 0.08x+2.5<=A<=0.08x+5.0 and 0.08x+4.0<=A<=0.08x+7.0 respectively. As a result, any deterioration of the white uniformity of the screen which might result from color mixing is prevented, thereby producing a fluorescent screen with superior characteristics.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a method for forming a color picture tube phosphor screen.

In particular, the present invention relates to a method for forming a color picture tube phosphor screen with excellent characteristics of white uniformity without color mixture.

[Technical background of the invention and its problems]

A phosphor screen is formed on the inner surface of a color picture tube panel in the following manner. Polyvinyl alcohol (hereinafter referred to as PV) contains phosphors that emit blue, green, and red colors on the inside of the panel.
A photosensitive phosphor slurry (hereinafter referred to as pre-slurry, green slurry, and red slurry) containing A) as the main component and ammonium dichromate added thereto is sequentially applied, and the panel is shaken off to form a predetermined phosphor layer. After removing the excess slurry from the inner surface of the panel, dry it, attach a prescribed shadow mask, and irradiate it with ultraviolet rays to harden the slurry coating at the predetermined position, and remove the slurry coating in the unirradiated areas by washing with water.
A dot-shaped or band-shaped phosphor layer is formed on the inner surface of the panel.

In the process of forming such a phosphor screen, as a method of forming a color picture tube phosphor screen with excellent white uniformity without color mixing, the solid content of PVA in the blue, green, and red slurries applied to the inner surface of the panel/all of the slurry is There are methods such as regulating the solvent ratio or reducing the PVA solid content/phosphor ratio.

The phenomenon of color mixing is that if the PVA solid content in the first color slurry, for example, the blue slurry, is high, the PVA will not be sufficiently cured even after the curing process with ammonium dichromate and the drying process of the blue phosphor after washing with water. PVA in the next applied slurry e.g. green slurry,
Forms chemical and physical bonds with ammonium dichromate, green phosphor, etc.

That is, the OH groups of uncured PVA in the blue phosphor layer form chemical and physical bonds with Cr of the dichromate, the OH groups of PVA, or the green phosphor in the green slurry, resulting in color mixture. In other words, even after the phosphor layer is formed, the green phosphor remains in the blue phosphor layer, deteriorating the uniformity of the front side surface, resulting in a problem of deteriorating the white uniformity of the screen.

The above-mentioned countermeasure against such color mixing phenomenon is to reduce the solid content of PVA in the phosphor layer before irradiation with ultraviolet rays, thereby sufficiently photocuring and thermally curing the PVA in the phosphor layer, thereby removing uncured PVA. It is something that reduces

In other words, it can be seen that the color mixing quality of the phosphor screen changes depending on the ratio of the phosphor and PVA solid content in the phosphor layer. However, even if this ratio is regulated with the above measures, if the machine index of the phosphor layer formation process changes, the amount of sedimentation of the phosphor in the slurry applied to the inner surface of the panel will change, so it is necessary to apply the same slurry to the inner surface of the panel. Also, the ratio of the phosphor and PVA solid content in the phosphor layer changes due to the difference in machine index. Therefore, there is a drawback that the quality of the phosphor screen changes.

[Purpose of the invention]

The present invention has been made to eliminate such conventional drawbacks, and an object of the present invention is to provide a method for forming a color picture tube phosphor screen with excellent white uniformity formed on the inner surface of the panel.

[Summary of the invention]

In the present invention, the above ratio is always maintained at the usage ratio by regulating the ratio of PVA solid content weight/phosphor weight in the slurry in accordance with the effective settling time of the phosphor in the slurry applied to the inner surface of the panel. death.

In addition, by regulating the degree of polymerization and saponification of PVA, the viscosity of all the solvents in the slurry, and the specific gravity of the phosphor in the slurry, we can prevent deterioration of the white uniformity of the screen due to color mixing and create a phosphor screen with excellent characteristics. Form. That is, in order to form such a phosphor screen, when the value of the photosensitive resin solid content weight/phosphor weight of the slurry is A, and the effective settling time of the phosphor is X seconds, the first color slurry is 0.08x+
1.5≦A≦0.08x+3.5. For the second color slurry, 0.08x+2.5≦A≦0.08x+5.0. Third
For color slurry, 0.08x+4.0≦A≦0.08x
+7.0, and the PVA used in the slurry (71 polymerization degree is 2000 to 3000. Saponification degree is 86.5 to 89%
The viscosity of all the solvents in the slurry is 5 to 20 rps for the first color slurry and 10 to 30 rps for the second color slurry.
cps, the third color slurry is 15-35 cps, and the specific gravity of the phosphor in the slurry is 3.
8 to 4.2, and 4.8 to 5.2 for the third color.

[Embodiments of the invention]

Examples of the present invention will be described below.

A phosphor layer is sequentially formed using a blue slurry for the first color, a green slurry for the second color, and a red slurry for the third color to form a phosphor screen. At this time, when the weight ratio of the PVA solid content and the phosphor in the slurry is A, and the effective settling time of the phosphor is X seconds, the first color is 0.08x+1.5≦A≦0.08x+3.
5 2nd color 0.08x+2.5≦A≦0.08x+5
．． 0 3rd color 0.08x+4.0≦A≦0.08x+
7.0 to form a fluorescent screen.

FIG. 1 relates to the first color blue slurry,
The value of the photosensitive resin solid content multilayer/phosphor weight of the blue slurry is A, and the vertical axis is the effective settling time of the blue phosphor on the panel surface, that is, the blue slurry applied to the panel surface becomes a uniform phosphor layer. In order to do this, the time of the process name for shaking off the excess pre-thriller on the inside of the panel is taken as X seconds on the horizontal axis.

When A is smaller than 0.08 x + 1.5, that is, in a range below straight line (1) in FIG. 1, dot-shaped or band-shaped phosphor layer defects occur. This occurs because there is not enough PVA to adhere the phosphor to the inner surface of the panel. Moreover, if A is larger than 0.08x+3.5, that is, in the range above the straight line (■) in Figure 1, the photocuring and thermal curing of PVA in the slurry coating will be insufficient, resulting in uncured PVA. , mixing colors and reducing quality. On the other hand, the slurry coating on the inner surface of the panel is too thick, which reduces the ultraviolet transmittance in the phosphor layer during the photocuring process, and the PV
This results in insufficient curing of A, resulting in chipping of the phosphor layer. In other words, a good phosphor screen can be obtained by using a material within the range between straight lines (2) and (2).

FIG. 2 relates to the second color green slurry,
When A is smaller than Q, 08x+2.5, that is, in the range below the straight line ■ in the figure, the viscosity of the slurry is so low that it becomes impossible to uniformly apply the slurry to the inner surface of the panel. In other words, since there is blue phosphor on the inner surface of the panel, if the viscosity of the green slurry is low, it will be affected by the blue phosphor layer and the green slurry will not be able to spread uniformly over the entire inner surface of the panel, resulting in uneven coating. Also, as with the blue slurry, the phosphor layer is missing. Moreover, if A is larger than 0.08x+5.0, that is, in the range above the straight line (■) in the figure, loss of the phosphor layer and color mixing will occur as described above.

FIG. 3 relates to the third color red slurry,
A is smaller than 0.08x+4.0, that is, direct All (
In the range below 1), uneven coating of the slurry and loss of the phosphor layer occur as described above, and A is 0.08x+7.
．． In the range greater than 0, that is, above the straight line ■.

Similarly to the above, the phosphor layer is missing.

That is, the values of A for the blue slurry, green slurry, and red slurry are each 0.08x+1.5≦A<0.08x+3.
5゜0.08x+2.5≦A≦0.08x+5.0.0
．． By selecting 08x+4.0≦A≦0.08x+7.0, it is possible to reproduce an image with good white uniformity that does not cause color mixing. In FIGS. 1 to 3, it is preferable to use the range between straight line (1) and straight line (2).

Furthermore, in the case of blue slurry, the viscosity of the slurry is not affected by the base material on the inner surface of the panel, so even if the slurry viscosity is low to some extent, uneven coating will not occur.

However, the green slurry needs to have a certain level of slurry viscosity in order to form a uniform slurry coating on the irregularities on the inner surface of the panel on which the single layer of blue slurry has been formed. On the other hand, if the slurry viscosity is too high, the slurry may not be uniformly spread on the inner surface of the panel within a specified time, resulting in uneven slurry application. Therefore, the slurry viscosity for obtaining a uniform slurry coating without being affected by the underlying phosphor layer is in the order of the first color, the second color, and the third color. The viscosity (at 21°C) to obtain a good slurry coating is 5-20c for the first color.
ps, 2nd color 10~30cps, 3rd color 15~
35 cps is appropriate.

The degree of polymerization of PVA is preferably 2000 to 3000.

If a material with a particle size smaller than 2000 is used, the phosphor layer may be missing due to a decrease in adhesion to the inner surface of the panel, and a large amount of dichromate-based photosensitizers such as ammonium dichromate may be added, resulting in a decrease in brightness. , 3000, there is a problem in forming a good fluorescent film. In addition, regarding the saponification degree of PVA, if 86.5 to 89% is used,
This is suitable because it can improve the developability of the phosphor coating film during water washing. Furthermore, regarding the specific gravity of the phosphor in the slurry, it is recommended to use a slurry with a specific gravity of 3.8 to 4.2 for the first and second colors, and a phosphor of 4.8 to 5.2 for the third color. It is suitable for coating to form a good fluorescent film.

〔Effect of the invention〕

By forming a phosphor screen on the inner surface of a panel using the method of the present invention, it is possible to form an image with good white uniformity without causing problems such as uneven slurry application or missing phosphor layers, and without causing color mixture. is an extremely useful method industrially.

[Brief explanation of drawings]

Figures 1, 2, and 3 show the relationship between the weight ratio of the PVA solid content to the phosphor in the slurry of the first, second, and third colors, respectively, and the effective settling time of the phosphor. It is an explanatory diagram.

Claims (4)

[Claims] (1) When forming phosphor layers that emit light in blue, green, and red colors at predetermined positions on the inner surface of the panel, a photosensitive material whose main component is polyvinyl alcohol containing phosphor layers that emit light in blue, green, and red colors. The value of photosensitive resin solid content weight/fluorescent weight of the photosensitive phosphor slurry is defined as A, and the time taken for the phosphor in the photosensitive phosphor slurry applied to the inner surface of the panel to settle on the inner surface of the panel, that is, the photosensitive phosphor slurry When x seconds is the time required to apply this to the inner surface of the panel and shake off the excess photosensitive phosphor slurry on the inner surface of the panel in order to form a uniform phosphor layer, the photosensitive phosphor slurry of the first color is 0. .08x+1.5≦A≦0.08x+3.5, 0.08 in the photosensitive phosphor slurry of the second color
x+2.5≦A≦0.08x+5.0, and in the photosensitive phosphor slurry of the third color, 0.08x+4.0≦
A method for forming a color picture tube phosphor screen, characterized in that A≦0.08x+7.0. (2) Polyvinyl alcohol has a polymerization degree of 2000 to 30
2. The method for forming a color picture tube phosphor screen according to claim 1, wherein the saponification degree is 86.5 to 89%. (3) The viscosity (value at 21°C) of all solvents in the photosensitive phosphor slurry is 5 to 20 cps for the first color photosensitive phosphor slurry and 10 to 20 cps for the second color photosensitive phosphor slurry. 2. The method for forming a color picture tube phosphor screen according to claim 1, wherein the photosensitive phosphor screen of claim 1 is 30 cps, and 15 to 35 cps for the third color photosensitive phosphor slurry. (4) The specific gravity of the phosphor in the photosensitive phosphor slurry is 3.8 to 3.8 in the first and second color photosensitive phosphor slurries.
4.2, 4 in the third color photosensitive phosphor slurry
．． 8 to 5.2. The method of forming a color picture tube phosphor screen according to claim 1, wherein the color picture tube phosphor screen is 8 to 5.2.