JPS6074230A - Method of forming fluorescent screen of cathode ray tube - Google Patents

Abstract

PURPOSE:To increase performance of resolution in an organic film and to enable to form a good fluorescent screen by adding special amount of chromate including Cr<3+> to filming liquid including acrylic emulsion, as a main component, to form the organic film. CONSTITUTION:Phosphor slurry composed of phosphor and so on is applied to the inner surface of a panel 1 and the three colored fluorescent film 2 is formed through drying, exposure and development. The surface of the formed fluorescent film 2 has concave portions and convex portions, and it is impossible to form a smooth reflecting film as it is even when Al is vacuum vaporized on it. Accordingly, the organic film 3 is formed as an intermediate layer and the Al vacuum vaporization film 4 is formed on it. In this case, 0.001-5wt% of chromate, such as sodium dichromate, including Cr<3+> is added to filming liquid including acrylic emulsion, as a main component, to form the organic film. Whereby, it is possible to increase performance of resolution in the organic film and the form a good fluorescent screen.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for forming a fluorescent surface of a cathode ray tube, and particularly to a method for forming an organic film used as a base for a metal back film.

[Background of the invention]

Conventionally, for example, when forming the fluorescent surface of a color picture tube, the inner surface of the panel is irradiated with an electron beam to produce a red color.

After depositing three types of phosphors that emit blue and green light in dots or stripes, the surface of the phosphor layer is coated with an organic film, and then aluminum is vapor-deposited on the soil. This forms a so-called metal back film.

Here, the purpose is to fill in the irregularities of the organic film il''j:1 phosphor layer so that the metal back film can be formed flat so that it can fully perform its function as a reflective film. After forming a metal back film, for example, an aluminum vapor deposited film, it is decomposed and removed by heating, thereby making the metal back film adhere to the phosphor layer.

Conventionally, the above-mentioned filming liquid has been used that has an acrylic emulsion as its main component, but its decomposition properties are not always sufficient and the film sometimes remains without being decomposed locally, or discoloration occurs due to the gas generated. There was a problem. A method of adding colloidal silica has been proposed to improve decomposability, but the effect was not sufficient.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide a method for forming a fluorescent surface of a cathode ray tube, which can improve the decomposability of an organic film and form a good fluorescent surface. There is a particular thing.

[Summary of the invention]

In order to achieve such an object, the present invention is directed to adding chromate containing Cr3+ to a filming liquid mainly composed of an acrylic emulsion that forms an organic film.
It is added in an amount of 5 wt%. Hereinafter, the present invention will be explained in detail using Examples.

[Embodiments of the invention]

As shown in FIG. 1, a phosphor slurry consisting of polyvinyl alcohol, ammonium dichromate, and a phosphor is applied to the inner surface of a panel 1, and then dried, exposed, and developed to form a three-color phosphor film 2f. The fluorescent film 2 formed here has a thickness of about 10 μm and an average grain size of 3 μm.
Since the phosphor particles 2a are laminated in two to three layers, the surface naturally has irregularities, and even if aluminum is deposited, a smooth reflective film cannot be formed as it is. Therefore, next, an organic film 3 is formed as an intermediate layer, and an aluminum vapor deposition film 4 is formed thereon.

In this case, the film-forming material commonly used is an emulsion solution based on acrylic resin;
When a film was formed using an emulsion liquid that did not use additives, the baking process after the aluminum vapor deposition caused problems, especially in the skirt part, which is the connection part of the panel 5 to the funnel 6, as shown by A in FIG. Noticeable areas and areas where the glass has become discolored due to scratches were observed.

This acrylic emulsion liquid has a concentration of 0.02~
When an organic film 3 was formed using Filmink solution containing 0.2 wt% ammonium dichromate and treated in the same process, the aluminum surface and the frit glass welded part without any undecomposed or discolored parts as described above were removed. I was able to get it.

Similarly, good results were obtained using a filming liquid to which other chromates including sodium dichromate, potassium chromate, and Cra+ were added. The amount added is 0
．． Approximately 0.001 to 5 wt% is appropriate, and if it is less than 0.001 vt%, sufficient improvement effect cannot be obtained, and 5 wt%
If there is too much chromium ion, chromium ions remain in the phosphor layer, causing the phosphor's body color to change. Furthermore, since chromium ions have the property of decomposing graphite in the light-absorbing coating layer, which is usually graphite, this is undesirable because it reduces the effectiveness of the light-absorbing coating.

〔Effect of the invention〕

As explained above, according to the present invention, by adding chromates to a filming liquid that forms an organic film, its thermal decomposition is promoted, and discoloration due to undecomposed residues and generated gas is prevented. However, it is possible to form a fluorescent surface with good smoothness of the metal back film.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the structure of a fluorescent surface during multilayer formation according to the present invention, and Fig. 2 is a cross-sectional view showing the inconveniences when forming by the conventional method, in other words, to clarify the effects of the present invention. FIG. 2 is a perspective view of a cathode ray tube bulb. 1... Panel, 2... Fluorescent film, 211...
・Fluorescent particles, 3...Film, 4...
・Aluminum vapor deposited film. Agent Patent Attorney Akio Takahashi (')

Claims (1)

[Claims] After sequentially forming a light-absorbing coating layer, a phosphor layer, an organic film, and a metal reflective film on the inner surface of the panel, the panel is heated to decompose and remove the organic film and adhere the metal reflective film to the phosphor layer. In the method for forming a fluorescent surface of a cathode ray tube, the organic film is mainly composed of an acrylic emulsion and contains 0.001% of chromate containing Cr3+.
A method for forming a fluorescent surface of a cathode ray tube, the method comprising forming a fluorescent surface of a cathode ray tube using a filming liquid containing ~5 wt%.