JPS60254536A - Manufacture of cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent any lacquer film from remaining after pure water trimming by applying an aqueous sodium hydroxide solution to a part of the inner surface of the funnel of a glass bulb before an organic solvent lacquer is sprayed over the inner fluorescent surface of the face of the glass bulb. CONSTITUTION:After a fluorescent surface 3 formed on the inner surface of the face 2 of a bulb 1 is wetted by pure water, an aqueous sodium hydroxide solution 40 is poured over an area (between A and B) of the inner surface of a funnel 9 to apply the solution 40 to the area. Then a lacquer of an organic solvent such as toluene principally composed of an acrylic resin is sprayed over the fluorescent surface 3 to form a lacquer film 8. Next, necessary lacquer films adhering to the funnel 9 are removed by pouring pure water over the films. After that, an aluminum film is formed by vapordeposition before it is baked, thereby completing the fluorescent surface 3. Consequently, the reliability of the cathode-ray tube can be improved by easily and completely removing the unnecessary lacquer films by sodium hydroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a cathode ray tube, and more particularly to a method V for trimming a lacquer coating formed on the inner surface of a cathode ray tube.

[Prior Art] FIG. 1 shows an outline of a general cathode ray tube. In this figure, (1) is the glass bulb, (2) is the face part, and (3) is the glass bulb.
) is a phosphor screen, (4) is an aluminum vapor deposited film as a metal back, (5) is a graphite film, and (6) is an electron gun that emits electrons to cause the phosphor (3) to emit light.

Next, the manufacturing method of the cathode ray tube described in 2 is shown in Fig. 2(a).
(bL (C) will be explained. As shown in Figure 2 (a), first, the inner surface of the glass bulb (1) forming the fluorescent screen (3) is coated with a hydrofluoric acid aqueous solution, a sodium hydroxide aqueous solution and pure water. Wash using water. Next, for example,
Inject a predetermined amount of an aqueous solution of barium acetate as an electrolyte,
Thereafter, a suspension of a predetermined phosphor (3a) dispersed in an aqueous solution of wood glass as an adhesive is injected and left to stand for a predetermined period of time to precipitate the phosphor (3a). After the phosphor (3a) has settled, the glass bulb (1) is slowly tilted to complete the deposition of the phosphor (3a), that is, the formation of the phosphor screen (3). This method is generally called a precipitation method, and after the phosphor (3a) is deposited by this precipitation method, the aluminum vapor deposited film (4) is formed;
) If aluminum is directly deposited on the fluorescent surface (3), a continuous deposited film will not be formed, so a very thin organic film is formed on the fluorescent surface (3) for filming, and then aluminum is deposited.

That is, as shown in Fig. 2(b), first the phosphor screen (3) is moistened with pure water, etc., and most of the phosphor (3a) is covered with a water film (7), and then the acrylic resin is mainly covered. Spray organic solvent lacquer such as toluene and ethyl acetate as ingredients,
A very thin lacquer film (8) is formed on the water film (7). Next, remove the lacquer coating ( 8) is removed by pure water (23) jetted at a constant pressure from the hole (22) of the nozzle (21). This is because when the lacquer coating H (8) is formed on the uncoated area of the phosphor (3a), the aluminum evaporated film (0) deposited on this area causes blistering during the subsequent baking process. This is done to prevent it from peeling off from the funnel part (8) of the cathode ray tube (1).Next, the phosphor screen (3) is dried using dehumidifying air, etc., and graphite 115) is applied to the designated area. Dry this in the same way. Finally, aluminum is vapor-deposited, and the aluminum vapor-deposited film (4) is formed.
After forming the phosphor screen, the organic material used in forming the phosphor screen is
It is decomposed and removed by a baking process of heating at 00 to 420°C to complete the formation of the phosphor screen (3).

A lacquer coating (8) is thus formed thereon. Aluminum evaporation @ (4) is formed to smooth the surface to prevent unevenness, and the aluminum evaporation film (4) prevents ion burning of the phosphor (3a) by the electron beam and improves luminous efficiency. It is formed for the purpose of increase.

An electron gun (6) is further sealed on the glass bulb (1) on which the phosphor screen (3) has been formed, and then the inside of the glass bulb (1) is evacuated to remove the electron gun (6). The cathode ray tube shown in FIG. 1 is obtained.

In the pure water trimming of the lacquer coating (8) in the above method, the effects on the glass bulb (1) vary depending on changes in the indoor atmosphere, that is, the level of room temperature and the level of humidity. This also affects the drying speed of the coating (8), and the lacquer coating (8) inside the funnel portion (8) cannot be completely removed by the pure water trimming alone.
There was some lacquer coating (8) remaining in some areas. Small cathode ray tubes are susceptible to this, and the lacquer coating (8) remaining inside the funnel part (8) will cause blistering as shown in Figure 3 during the subsequent baking process, and this will peel off and cause the phosphor screen to bulge. If it adheres to the electron gun (3), the luminescence efficiency will be reduced, and if it adheres to the electron gun (6), it will cause sparks.

[Summary of the Invention] The present invention has been made to solve the above-mentioned conventional drawbacks. Before spraying the organic solvent lacquer, an aqueous sodium hydroxide solution is applied by pouring it onto the inner surface of the funnel part,
The remaining lacquer coating was removed by subsequent trimming with pure water.

- [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. First, in the same manner as before, that is, as shown in FIG. 2(b), the glass bulb (1) on which the phosphor (3a) has been deposited is moistened with pure water (7), and The glass bulb (1) is rotated at a predetermined rotation speed. This is to adjust the amount of the water film (7) and to prevent unevenness of the lacquer film (8).

Next, as shown in FIG. 4 showing an embodiment of the present invention, an aqueous sodium hydroxide solution (40) is poured onto the inner surface of the funnel portion (9) of the glass bulb (1).

Ru. The application line is the pure water trimming line (
From A) to 5 to 10 m + below the fat neck (lO) side. This coating line was designated as (B), and the concentration of the sodium hydroxide aqueous solution (40) was 10% by weight.

Moreover, the inner surface coating only needs to be enough to cover the entire inner surface of the funnel part (9), and there is no need to apply the coating for a long time.

The aqueous sodium hydroxide solution (40) coated on the inner surface of the funnel portion (3) in this manner is then sprayed with an organic solvent lacquer and rotated at a predetermined number of rotations for a predetermined period of time. This is also for adjusting the amount of lacquer coating (8), and is the same method as the conventional method. Next, trim with pure water at 60~
This is done for 90 seconds, which is exactly the same as before. At this time, due to the sliding action of the sodium hydroxide aqueous solution (40), the lacquer film (8) on top of the sodium hydroxide aqueous solution (40) does not remain and becomes pure water (Fig. 2 (C) )) Trimmed in (23). Next, it is dried with a dehumidifying air to complete the formation of the lacquer film (8). Note that the subsequent manufacturing steps are the same as those of the above-mentioned prior art, so the explanation thereof will be omitted.

Funnel part of the above sodium hydroxide aqueous solution (40) (
9) According to the inner surface coating and pure water trimming method, the pure water trimming line (A) is coated with a sodium hydroxide aqueous solution (40
) is 5 to 10 mm higher than the inner coating line (B),
Sodium hydroxide could be completely removed by pure water trimming, and there were no adverse effects such as blistering caused by lacquer coating residue. Further, this embodiment was applied to a 7 inch square cathode ray tube, but the smaller the tube, from 6n·1 to 31;j, the greater the effect, and the simpler the application. Further, although the purpose can be achieved with the concentration of the sodium hydroxide aqueous solution ranging from several weight % to 40 weight %, it is desirable to set the concentration to 8 to 10 weight % from the viewpoint of effectiveness and safety.

[Effects of the Invention] According to the invention described above, blisters due to the lacquer film remaining after baking can be prevented by simply applying an aqueous sodium hydroxide solution to the inner surface of the funnel portion immediately before spraying the organic solvent lacquer. Therefore, drawbacks such as reduction in phosphor screen brightness and sparks due to peeling of the aluminum vapor deposited film are eliminated, and process yield and voltage resistance characteristics are improved.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an example of a cathode ray tube, and Figure 2 (a) is a cross-sectional view for explaining the conventional manufacturing process of a cathode ray tube.
SZ diagram (b) is a partially enlarged view of Figure 2 (a), and Figure 2 (c
) is a cross-sectional view showing the conventional trimming process, and Figure 3 shows the blistering shape of the aluminum vapor deposited film! Simplified diagram showing 匪, No. 4
The figure is a sectional view of the application of a sodium hydroxide aqueous solution to the inner surface of a funnel according to an embodiment of the present invention. (1)...Glass pulp, (2)...Face part,
(3)... Fluorescent screen, (4)... Metal back, (8
)... Lacquer coating, (8)... Funnel part, (4
0)... Sodium hydroxide aqueous solution. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa 1151 Figure 2 (a) Figure 2 (C)

Claims (1)

[Claims] (1) A phosphor screen is formed on the inner surface of the face of the glass bulb, and a lacquer film is formed by spraying a lacquer made of an organic solvent containing acrylic resin as a main component onto the phosphor screen, and the inner surface of the funnel section of the glass bulb is coated with lacquer. After a trimming step in which the lacquer film formed on the lacquer film is removed using pure water or an equivalent liquid, a metal back is applied on the lacquer film, and the lacquer film is decomposed and removed by heating. A method for manufacturing a cathode ray tube, characterized in that before spraying the lacquer, an aqueous sodium hydroxide solution is applied to the inner surface of the funnel portion.