JPH0357139A - Formation of conductive film - Google Patents

Abstract

PURPOSE:To remove graphite banks in the corners of a square bulb and obtain an uniform coat by preliminarily spraying an oily resin on the outer surface of a cathode-ray tube bulb requiring no conductivity followed by drying, and dipping it in a graphite suspension with its funnel part down. CONSTITUTION:A cover 1 of solvent-resistant plate is fitted to a funnel opening part, and an oily resin and an acrylic resin solution are sprayed from the bulb outer surface and upper part followed by drying to form a first coat 2 only on the outer surface. Then, the bulb is dipped in a graphite suspension 4 with a funnel part 5 down up to the part squiring a graphite coat as a conductive film to form a graphite coat 3 which is a second coat. When the bulb is pulled up, the graphite coat 3 is formed only on the inner surface. Burning is conducted to decompose the acrylic resin, whereby the first coat 2 on the outer surface is completely removed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a conductive film on the inner surface of a bulb suitable for manufacturing cathode ray tubes, such as small cathode ray tubes.

Conventionally, as shown in FIG. 5, a square small cathode ray tube has a graphite coating film formed on the inner surface of the bulb for electrical conduction to form a conductive path between the fluorescent film and the electron gun. As shown in FIG. 8, the graphite coating film 3, which is a conductive film, is made by using a rod thinner than the valve neck 8, and applying graphite with a brush attached to the tip of the rod.

In other words, insert this brush through the funnel opening,
Slide the brush in the direction of the neck 6 while rotating the entire funnel from the required point, and apply to the boundary between the neck 6 and the funnel 5. Next, by changing the pushing angle of the brush, graphite was applied to the bottom of the step of the funnel, as shown in FIG.

By the way, in the above-mentioned conventional graphite coating method, the funnel 5 has a square shape as shown in FIG. 5, and graphite accumulation tends to occur at a corner of the funnel opening, resulting in film unevenness. Peeling was likely to occur. Further, there was a drawback that a uniform graphite coating film 3 could not be obtained. In addition, the work was difficult and took a long time, and there were problems in terms of efficiency.

Therefore, the present invention was proposed in order to solve the above problems, and an object of the present invention is to provide a new and improved method for coating and forming a conductive film.

In order to solve the above-mentioned problems, the present invention is to apply graphite to a cathode ray tube bulb by first spraying and drying an oil-based resin on the outer surface of the bulb, which does not require electrical conductivity, and then applying graphite suspension to the cathode ray tube bulb. Immerse it in the turbid liquid with the funnel part facing down to a predetermined position. Next, the first coating of oil-based resin is separated by firing or the like to form a graphite coating film on the inner surface of the bulb which needs to be electrically conductive. When removing the outer coating,
The graphite coating applied to the outer surface is also removed at the same time.

In summary, forming a first coating on the outer surface of the valve;
Formation of a conductive film on a bulb, which consists of a step of immersing the bulb after this film formation into Milfil solution of the conductive member to a predetermined position to form a second film on the inner surface of the bulb, and a step of removing the first film. A method is disclosed.

Negative U Ratio According to the above configuration, since the oil-based resin of the first coating and the graphite of the second coating are water-based, they can be separated, and a graphite coating film can be reliably formed in areas that require conductivity. . It is also acceptable to use an aqueous emulsion for the first coating, since the second coating can be fired and peeled off at the same time.

Moreover, since gravity is used to immerse the bulb in graphite and take it out, the coated surface is uniform, and there are no graphite pockets at the corners of the square bulb, resulting in a uniform film.

This method can also simplify the work process.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be explained by way of embodiments with reference to the drawings.

In Figure 1, a cover 1 made of a solvent-resistant plate is fitted into the funnel opening, and a mist of oil-based resin, acrylic resin solution, etc. is sprayed from the outer surface and upper part of the valve, and dried to form a first coating 2 only on the outer surface. form.

Next, as shown in FIG. 2, the funnel part 5 of the bulb is placed downward and the part where the graphite coating film as a conductive film is required is immersed in the graphite suspension 4 to apply the graphite coating as the second coating. A film 3 is formed. Next, when the bulb is pulled upward, the first coating WX2 and the second coating of the graphite coating film 3 are separated during the lifting process, making it difficult for the graphite coating to adhere to the outer surface as shown in FIG. Next, it is fired to decompose the acrylic resin. Thereby, the first covering of the outer surface 1! X2 is completely removed.

As explained above, in this invention, by immersing the graphite brush coat in a graphite suspension, it is possible to eliminate the graphite clumps at the corners of the rectangular bulb and obtain a uniform coating film. This also simplifies the work and improves work efficiency.

[Brief explanation of drawings]

1 to 4 are sectional views of main parts of the bulb in each step in the method for forming a conductive film according to the present invention, FIG. 5 is an outline diagram of a rectangular bulb, and FIG. 6 is a conventional graphite coating method. FIG. 3 is a cross-sectional view of a valve with a completed membrane. 2...First coating (resin film), 3...
Second coating (graphite coating film) 4...Graphite suspension, 5●・●...●facial layer, 6...Neck. Figure 1 Figure 3 Figure 4 Figure 4 Figure b Prisoner

Claims (2)

[Claims] (1) a step of forming a first coating on the outer surface of the bulb; a step of immersing the bulb after the coating has been formed in a suspension of a conductive member to a predetermined position to form a second coating on the inner surface of the bulb; A method for forming a conductive film for a bulb, comprising the step of removing a first film. (2) The method for forming a conductive film according to item 1, wherein the first film is formed using an oil-based paint, and the second film is formed using a conductive water-based paint such as graphite.