JPS63131431A - Fluorescent screen forming method for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To suppress the etching irregularity of a graphite film by pouring a liquid on the inner surface of a panel, removing a photo-resist film and a graphite film on the film from the inner surface of the panel, and forming a stripe-shaped light absorbing film. CONSTITUTION:A graphite liquid 2 diluted with water is poured on a photo- resist film formed in a pattern shape on the surface of a panel 1, the panel 1 mounted on a rotating device 3 is inclined and rotated, thereby the whole panel 1 is coated with the graphite liquid 2. After the graphite film is dried, a pre-coating liquid is poured on the inner surface of the panel 1 while the panel 1 is rotated, then the pre-coating liquid infiltrates into the graphite film. In addition, while this pre-coating liquid is still wet, an etching liquid is poured on the inner surface of the panel 1, then the photo-resist film is expanded in about a minute. Next, water is sprayed on the inner surface of the panel 1 with a spray, then the photo-resist film and the graphite film on it are removed, and a stripe-shaped graphite film (light absorbing film) 4 is formed on the inner surface of the panel 1. Accordingly, no etching irregularity of this film is observed, and no pinhole 6 is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for forming a phosphor screen of a color picture tube panel.

(Prior Art) In general, when forming the phosphor surface of a color cathode ray tube, graphite holes are formed as a light absorption film between regularly arranged three-color phosphors in order to improve the contrast of the screen. These graphite holes are created by applying a photoresist solution, such as a mixture of polyvinyl alcohol and ammonium dichromate, to the inner surface of the face plate of a color cathode ray tube. The emitted light is used to expose each color a total of three times in accordance with the positions of the red, blue, and green phosphor picture elements. Furthermore, the unexposed areas are developed by spraying warm pure water, etc. The inner surface of the panel is coated with a graphite solution containing graphite powder as the main component (for example, Hitazol GA-66M manufactured by Hitachi Powder Metallurgy Co., Ltd. diluted with water). After drying, an acidic etching solution such as nitric acid-ammonium nitrate is injected, the panel is rotated for about 1 minute to swell the photoresist under the graphite film, and heated pure water is applied for 6 to 6 minutes. By spraying at a water pressure of Bkg/xi to remove the swollen photoresist together with the graphite film formed thereon, a hole (2) is formed in the particular light-absorbing film shown in FIG. In addition, in this hole forming method, as shown in Figure 3, there is a difference in the immersion time of the graphite film in the etching solution between the central part of the faceplate where the etching solution is first injected and the peripheral part where it later spreads, resulting in uneven etching and coloration. Significantly deteriorates the quality of the fluorescent surface of the cathode ray tube. As a method for suppressing such etching unevenness, for example, Japanese Patent Publication No. 59-22340 discloses a method of precoating the inner surface of the face plate with water or warm water before injecting the etching solution. However, if the etching solution is injected after precoating with water or hot water, the etching unevenness can be alleviated, but pinholes (00
At the same time, the shape of the hole becomes worse compared to the conventional one, which greatly reduces the quality of the fluorescent surface of the color cathode ray tube, resulting in defects.Also, as shown in Figure 5, some of the graphite in the R part and skirt part of the panel blend deteriorates. The degree of peeling and blackness is extremely reduced, and the red or green color applied after graphite holes are formed.
If blue phosphor adheres to the panel blend R section and skirt section and remains in the final product stage of the color CRT, unnecessary phosphor emission will be noticeable outside the effective area of the phosphor surface during operation of the color CRT. In some cases,

The reason for the occurrence of such holes in the graphite film, as well as the peeling of the ducts in the panel blend R section and skirt section, is that in the conventional manufacturing method, the etching solution is directly injected into the graphite film after the graphite solution has been applied and dried. The acidity of the etching solution strengthens the bonds between the graphite particles, whereas if the etching solution is pre-coated with water or warm water, the pre-coated water acts as an inclusion that weakens the bonds between the graphite particles and peels off the graphite film. This is to make it easier.

Furthermore, as a countermeasure against such defects, for example, the problem can be solved by adding 2 to 2% by weight of an acrylic emulsion of a thermosetting resin (for example, AC-33 manufactured by Nippon Brimar Co., Ltd.) to the graphite liquid described above. Perhaps due to the forced formation of a kind of graphite film, the hole shape becomes worse compared to the conventional one and the quality of the fluorescent surface deteriorates.

(Problems to be Solved by the Invention) Although the etching method using water or hot water precoating as described above can suppress etching unevenness,
The quality of the phosphor surface deteriorates due to pinholes that occur in a part of the light absorption film, and furthermore, the blackness of the panel blend R part and skirt part decreases, and the phosphor remaining on these parts becomes unusable when the color picture tube is operated. There is a problem in that it does not emit the necessary light but becomes defective.

Furthermore, when a thermosetting emulsion-added graphite liquid is used as a means to solve this problem, there is a problem that the shape of the graphite holes becomes poor.

An object of the present invention is to suppress uneven etching of a graphite film without degrading the quality of a color cathode ray tube, including the quality of the fluorescent surface.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a step of forming a pattern of a photoresist film on the inner surface of a color picture tube panel, a step of forming a light absorption film on the inner surface of the panel on which the photoresist film is formed, and a step of forming a pattern of a photoresist film on the inner surface of the panel on which the photoresist film is formed. A step of injecting a pre-coat liquid into the inner surface of the panel, which acts to strengthen the bonding force between the particles of the material constituting the light-absorbing film without causing swelling, and allowing the pre-coat liquid to permeate the photoresist film and the light-absorbing film.

A step of injecting an etching liquid into the inner surface of the panel while the precoat liquid is in a wet state to swell the photoresist film.

A process of forming a patterned light-absorbing film by injecting liquid into the inner surface of the panel and removing the photoresist film and the light-absorbing film on the film from the panel surface, and a step of injecting a phosphor between the patterned light-absorbing film. 1. A method for forming a phosphor screen of a color picture tube panel, the method comprising a step of adhering the phosphor screen.

(Function) When a pre-coat liquid is injected onto the photoresist film and the light-absorbing film formed in a stripe shape, this pre-coat liquid does not swell the photoresist film and strengthens the bonding force between particles constituting the light-absorbing film. Therefore, the adhesion of the light-absorbing film is strengthened. Subsequently, since the etching liquid is injected while the precoat liquid is still in a wet state, the permeation rate of the etching liquid into the graphite film becomes almost uniform over the entire surface compared to the case where there is no precoat liquid. Therefore, the adhesion of the light-absorbing film is improved, and uneven etching can be eliminated. When the light-absorbing film is made of graphite, the pre-coating liquid is preferably an acidic liquid, and as a result, the bonding force between the graphite particles becomes stronger. The reason for this is not clear, but it is thought that the dispersibility of the graphite particles deteriorates due to the acidity, causing the particles to aggregate.1 The pre-coat liquid suitable for the present invention is a sulfamic acid saturated solution containing 20 to
50% by weight aqueous solution, 10 to 50% nitric acid by weight in water, precious bones, etc. If the concentration of the precoat liquid is less than the lower limit below, the bonding force between graphite particles cannot be strengthened. If it exceeds this, the swelling of the photoresist film will progress, which is undesirable.

(Examples) The present invention will be explained in detail below using Examples. FIG. 1 is a schematic diagram of an apparatus used in the manufacturing method of the present invention.

By injecting a graphite solution (trade name: Hitazol) diluted with water onto the photoresist film formed in a pattern on the surface of the panel ■ using the usual method, the panel ■ placed on a rotating device ■ is rotated at an angle. Apply graphite liquid to the entire surface of the panel. After the graphite film dries, a precoat solution of a 30% by weight aqueous solution of a saturated sulfamic acid solution is injected into the inner surface of the panel without rotating the panel, and the precoat solution permeates into the graphite film. Furthermore, while this pre-coat solution is wet, an etching solution made of a saturated sulfamic acid solution is injected into the inner surface of the panel, and after about 1 minute, the photoresist film swells.First, when pure water is sprayed onto the inner surface of the panel, the photoresist film The graphite film thereon is removed, and a striped graphite film (light absorption film) is formed on the inner surface of the panel. No uneven etching was observed in this film, there were no pinholes, and the blackness of the film at the panel blend R portion and skirt portion remained as good as before.

Next, a phosphor slurry was applied to the inner surface of the panel using a conventional method, and exposure and development were performed to form a phosphor screen.

The phosphor screen of a color picture tube obtained using this panel showed good characteristics.

In the process of the present invention, if a sulfamic acid precoat solution with a concentration of less than 10% by weight is used, pinholes will occur in the graphite film after final etching, and the film in the R part of the panel blend and the skirt part will be damaged. blackness decreases,
Red applied after this.

It was confirmed that green-blue phosphor remained in the final product stage, and that the remaining phosphor emitted light during tube operation, that is, during electron beam scanning, degrading image quality. If a sulfamic acid precoat solution with a concentration exceeding 50% by weight is used, the graphite film after etching development will have uneven etching during precoating, which is not preferable.

On the other hand, a conventional film, that is, a film formed by injecting an etching solution of a sulfamic acid saturated solution onto the inner surface of the panel without injecting a precoat solution after drying the graphite film, showed uneven etching. As another method, a film formed by injecting water into a dried graphite film and then injecting an etching solution of a saturated sulfamic acid solution onto the inner surface of the panel improved etching unevenness, but pinholes were observed.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a color picture tube equipped with a light absorption film without unevenness or pinholes.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the manufacturing method of the present invention, Figure 2 is a diagram explaining the coating shape of the light absorption film, Figure 3 is a diagram explaining the state of uneven coating of the light absorption film, and Figure 4 is a diagram explaining the coating shape of the light absorption film. FIG. 5 is a diagram illustrating pinholes in the light absorption film, and is a diagram illustrating how the degree of blackness of the graphite film in the panel blend R portion and the skirt portion is reduced. 4... Light absorption film 5... Graphite hole 6.
...Pinhole agent Patent attorney Nori Chika Yudo Norio Ogo

Claims (2)

[Claims] (1) A step of forming a pattern of a photoresist film on the inner surface of a color picture tube panel, a step of forming a light absorption film on the inner surface of the panel on which the photoresist film has been formed, and a step of forming a light absorption film without causing the photoresist film to swell. A step of injecting a pre-coat liquid, which acts to strengthen the bonding force between particles of the substance that binds, into the inner surface of the panel and allowing it to permeate the photoresist film and a light-absorbing film; A patterned light-absorbing film is formed by injecting an etching solution to swell the photoresist film, and injecting liquid into the inner surface of the panel to remove the photoresist film and the light-absorbing film on the film from the panel surface. 1. A method for forming a phosphor screen for a color picture tube panel, comprising the steps of: forming a phosphor between the patterned light-absorbing films; (2) The method for forming a phosphor screen of a color picture tube panel according to claim 1, wherein the light absorption film is a graphite film, and the precoating liquid is an acidic aqueous solution.