KR940007645B1 - Fluorescent layer manufacturing method of crt - Google Patents

Abstract

The fluorescent layer has a fine layer structure and has improved luminance and contrast by using the manufacturing method. The method comprises the steps of: (A) manufacturing red luminance fluorescent substance by attaching indium sulfide under H2S circumstance and temperature of 700-950 degree (C); (B) grinding the substance and drying; (C) manufacturing fluorescent slurry using the dried powder and spraying the slurry inner side of a panel; and (D) exposing and developing a panel to form red luminance fluorescent pattern.

Description

Manufacturing method of fluorescent film for cathode ray tube

1 is a 200 times magnified photograph of a fluorescent film prepared according to a conventional method employing a red light-emitting phosphor having an iron oxide pigment.

2 is an enlarged 200 times photograph of a fluorescent film obtained by employing a red light-emitting phosphor having an indium sulfide pigment applied to the fluorescent film according to a conventional method.

3 is a 200 times magnified photograph of a fluorescent film obtained by employing a red light-emitting phosphor having an indium sulfide pigment attached to the fluorescent film according to Example 1 of the present invention.

4 is a 200 times magnified photograph of a fluorescent film obtained by employing a red light-emitting phosphor having an indium sulfide pigment attached to the fluorescent film according to Example 2 of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fluorescent film for cathode ray tubes, and more particularly, to a method for manufacturing a cathode ray tube fluorescent film having improved density and contrast and a dense film structure.

Pigment particles are attached to the surface of the red, green, and blue phosphor particles used in the color cathode ray tube to improve the contrast of the phosphor by absorbing light in some undesired regions of the phosphor.

Among these pigments, pigments introduced into red light-emitting phosphors such as Y ₂ O ₂ S: Eu, YVO ₄ : Eu, Y ₂ O ₃ : Eu, and the like are iron oxide (Fe ₂ O ₃ ) and cadmium sulfoselenide [Cd (S ₁ −). x, Sex), 0 <x <1] and copper oxide (Cu ₂ O).

In particular, iron oxide pigments are widely used because they have properties such as acid resistance, heat resistance, alkali resistance, etc., but when they are attached to the surface of the phosphor, they have a problem of improving coltrast but decreasing luminance. Therefore, it is required to develop a pigment having a vivid color and non-toxic.

In view of the above problems, the present inventor has disclosed a pigment-attached red light-emitting phosphor employing indium sulfide as a pigment in Korean Patent Application No. 91-23723 (filed December 20, 1991) and a method of manufacturing the same. The pigment-containing phosphor has an advantage that the luminance and contrast are improved and its manufacture is easy as a phosphor having high color purity.

An object of the present invention is to provide a method for producing a fluorescent film for cathode ray tube having excellent film properties by using the red light emitting phosphor with indium sulfide pigment described above.

In order to achieve the above object, in the present invention, an indium salt and a basic aqueous solution are added to a dispersion of a red light-emitting phosphor to precipitate indium hydroxide [In (OH) ₃ ] on the surface of the phosphor and placed in a heat-resistant crucible to form hydrogen sulfide (H ₂ S) gas. Calcining for 2 to 8 hours in an atmosphere of 700 to 950 ° C. under an atmosphere to prepare a red light-emitting phosphor having an indium sulfide pigment attached thereto; Ball milling and drying the calcined product together with pure water and a ball mill; Preparing a phosphor slurry using the dried material and applying the same to the inner surface of the panel to form a red phosphor pattern by exposure and development; It provides a method for producing a fluorescent film for cathode ray tube comprising a.

Examples of the red light-emitting phosphor include europium-activated yttrium sulfide phosphor (Y ₂ O ₂ S: Eu), europium-activated yttrium oxide phosphor (Y ₂ O ₃ : Eu), europium-activated yttrium phosphate vanadium phosphate phosphor (YVO ₄ : Any red light emitting phosphor such as Eu) can be used.

In addition, the hydrogen sulfide gas atmosphere during firing is formed by injecting hydrogen sulfide gas at a rate of 2 L / min, and the ball mill treatment is preferably performed at a speed of 30 to 50 rpm.

Looking at the manufacturing method of the fluorescent film for cathode ray tube of the present invention in detail as follows.

First, a red luminescent phosphor is added to pure water and stirred sufficiently to obtain a phosphor dispersion. A solution obtained by dissolving indium chloride (InCl ₃ ) or indium sulfate [In ₂ (SO ₄ ) ₃ ] in pure water is added to the phosphor dispersion and stirred. While stirring the mixed solution, a diluted basic aqueous solution is added to adjust the pH of the solution to 4-7. When a base is added, indium hydroxide [In (OH) ₃ ] precipitates on the surface of the phosphor, which is filtered and dried by a filter. The dried product is sieved with a 400 mesh sieve and placed in a heat-resistant alumina crucible. The crucible is electrically installed in the core and fired for 2 to 8 hours in a hydrogen sulfide gas atmosphere at a temperature in the range of 700 to 950 ° C. while sealing both ends. The calcined product having such a process is obtained by attaching indium sulfide (In ₂ S ₃ ) to the surface of the phosphor to obtain a red body color. This phosphor is agglomerated because it has been heat treated at a high temperature, and thus it is difficult to be used in a fluorescent film immediately after sieving. It is mixed with pure water and glass balls and ball milled for several hours at a speed of about 30 to 50 rpm to obtain a red light-emitting phosphor with indium sulfide pigment without aggregation. The phosphor-attached phosphors were then mixed with pure water, polyvinyl alcohol, ammonium dichromate, etc. according to a conventional process to prepare a phosphor slurry, and applied to the inner surface of the panel, followed by drying, exposure, development, and the like. A pattern is formed and subsequently green, blue, and phosphor patterns are formed as necessary to obtain a fluorescent film for cathode ray tube according to the method of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail.

Example 1

Europium-activated yttrium oxide phosphor (Y ₂ O ₂ S: Eu), which is a core phosphor, is dispersed in 600 g of pure water. 1.0435 g of indium sulfate [In ₂ (SO ₄ ) ₃ .9H ₂ O] (which is equivalent to 0.5 g of indium sulfide (In ₂ S ₃ ) obtained thereafter) is dissolved in 50 ml of pure water and added to the phosphor dispersion under stirring. Dilute sodium hydroxide (NaOH) in pure water, and dropwise dropwise to the solution to adjust the pH of the solution to 7. The solution is filtered, the filtrate is dried and sieved with a 400 mesh sieve and charged into a heat resistant alumina crucible. It is calcined at 950 ° C. for 3 hours while injecting 99.99% hydrogen sulfide gas at a rate of 2 l / min. The fired material is sieved with a 400 mesh sieve to obtain europium-activated yttrium sulphate phosphor with indium sulfide. 100 g of the pigmented phosphor is mixed with 150 g of glass balls and 60 g of pure water and milled for 1 hour at a low speed of about 30 to 50 rpm. After the separation of the ball, the fluorescent substance with pigment is dried and the fluorescent slurry for the cathode ray tube according to the method of the present invention is prepared by preparing the phosphor slurry according to a conventional method and introducing the same into the inner surface of the panel.

Example 2

Performed in the same manner as in Example 1, but the amount of hydrated indium sulfate [In ₂ (SO ₄ ) ₃ · 9H ₂ O] to 6.2613g (corresponds to 3g indium sulfide) fluorescence for cathode ray tube according to the method of the present invention Get the act.

[Comparative Example]

1.8 g of gelatin is dispersed in 600 ml of pure water and heated to 40 ° C. to prepare a gelatin aqueous solution. 300 g of Y ₂ O ₂ S: Eu fluorescent was added to the aqueous gelatin solution and stirred until uniform with a stirrer.

1.2 g of gum arabic is dispersed in 400 ml of pure water and heated to 40 ° C. to prepare an aqueous gum arabic solution. 0.48 g (0.16% by weight) of the red pigment Fe ₂ O ₃ is added to an aqueous arabic rubber solution and sufficiently stirred to obtain a pigment dispersion.

After mixing the obtained pigment dispersion and phosphor dispersion, pH is adjusted to 6 with stirring. When the solution is left to settle down, the supernatant is poured out and the precipitate is washed several times with water. The solid mass is dried at a content of 100 ° C. to obtain a phosphor with iron oxide pigment attached. The pigmented fluorescent substance thus obtained is employed on the inner surface of the panel to produce a fluorescent film for cathode ray tube.

Table 1 shows the luminance, contrast and color coordinates of the fluorescent films prepared in the above Examples.

TABLE 1

* Each of the measured values is a value measured using a demountable system.

It can be seen from Table 1 that the fluorescent film prepared according to the method of the present invention has further improved brightness and contrast effects. This is because the indium sulfide attached to the pigment is conductive, thereby preventing the charge up of the fluorescent film, thereby preventing the decrease of the brightness of the fluorescent film. It is thought to be because it improves.

1 is a 200 times magnified photograph of a fluorescent film prepared according to a conventional method employing a red light emitting phosphor with an iron oxide pigment according to a comparative example, and FIG. 2 is a red light emitting phosphor with an indium sulfide pigment. It is a 200 times magnification photograph of the fluorescent film obtained by employ | adopting for a fluorescent film in the state which does not ball-mill process after manufacture of a pigment by the method.

Each of the above pictures is a microscopic enlarged picture, and the black part is a black matrix stripe.

From the drawings, it can be seen that the fluorescent film obtained according to the embodiment of the present invention has a more dense structure than the fluorescent film prepared by attaching a conventional iron oxide pigment. It can be seen that the fluorescent film produced by employing the hole was severe.

As described above, the cathode film for the cathode ray tube manufactured according to the method of the present invention has a compact phosphor pattern film structure, thereby providing a cathode ray plate of higher quality.

Claims (5)

The addition of an indium salt with a basic aqueous solution to the dispersion of the red light-emitting phosphor deposit a hydroxide of indium in the phosphor surface and firing it into a heat-resistant crucible under a hydrogen sulfide (H ₂ S) gas atmosphere for a 700 to 950 ℃ temperature range 2 to 8 hours sulfide Preparing a red light emitting phosphor to which an indium (In ₂ S ₃ ) pigment is attached; Mixing the calcined product with pure water and a ball mill, followed by drying the ball mill; Preparing a phosphor slurry using the dried material and applying the same to the inner surface of the panel to form a red phosphor pattern by exposure and development; Method for producing a fluorescent film for cathode ray tube comprising a. The method according to claim 1, wherein the basic aqueous solution has a pH of 4 to 7. 2. The red light emitting phosphor according to claim 1, wherein the red light emitting phosphor is europium-activated yttrium sulfate phosphor (Y ₂ O ₂ S: Eu), europium-activated yttrium phosphor (Y ₂ O ₃ : Eu), europium-activated yttrium vanadate It is any one of fluorescent substance (YVO ₄ : Eu), The manufacturing method of the fluorescent film for cathode ray tubes. The method of claim 1, wherein the hydrogen sulfide (H ₂ S) gas atmosphere is formed by injecting hydrogen sulfide (H ₂ S) gas at a rate of ₂ L / min during firing. The method of claim 1, wherein the ball mill treatment is performed at a speed of 30 to 50 rpm.