JPS5893138A - Method of forming phosphor screen for cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a high quality CRT phosphor screen with reduced pinholes and mixing colors and with a good shape of picture elements using the optical adhesion method by forming the phosphor screen using a panel with its inner surface roughness of 4mu or less. CONSTITUTION:An optical adhesion coating with the average thickness of approximately 0.5mu is formed by coating the inner surface of the panel of a 10- inch color picture tube with an optical adhesion compound and drying it. In this case, a panel with its inner surface roughness of approximately 2mu is used. A green phosphor powder is applied to the inner surface of the panel after exposure and is made to adhere to the location that shows adhesion by exposure and then an excessive phosphor powder applied to a non-exposure section is removed through air spray phenomenon. Then, a phosphor screen consisting of three-color phosphor stripes is formed by sequentially coating each of the corresponding emission sections on the inner surface of the panel with blue and red phosphors in the same way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a fluorescent surface of a cathode ray tube by a photoadhering method.

One method for forming the fluorescent surface of a cathode ray tube, such as a color receiving tube, is to use a powdered phosphor and a substance that becomes sticky when exposed to light. Specifically, in this method, first, a substance that develops tackiness upon exposure to light is applied to the inner surface of a pulp panel. Such substances include
For example, the main component is a double salt of a diazo compound and a metal halide salt (zinc chloride, cadium chloride, tin chloride, etc.) or a fluorinated nonmetal salt (such as fluoroboric acid), and as an additive, a polymer is added. A composition containing a compound, a surfactant, etc. is used, and in these compositions, the pdiazo compound decomposes upon exposure to light, liberating a deliquescent substance, which becomes a ball that collects moisture in the air. It is thought to be sticky. Next, a color selection electrode such as a shadow mask is attached to the panel, and a portion to be coated with a first color, for example, a green light-emitting phosphor, is exposed on an exposure table. At this time, the exposed areas become sticky due to the light reaching through the holes in the shadow mask. Next, the phosphor powder of the first color is poisoned to the inner surface of the panel, and is sufficiently adhered to the sticky areas. Next, the phosphor picture elements of the first color are formed on the inner surface of the panel by removing the excess phosphor powder applied to the unexposed areas using an air bubble U- or the like.

Furthermore, by sequentially carrying out the steps following the above exposure for the other two colors, three-color phosphor picture elements of green, blue, and red can be completed.

However, when forming a fluorescent surface using such a photoadhesive method, if a thin adhesive film is applied to the inner surface of the panel, if the coating is applied after applying the phosphor powder, localized phosphorescence may occur. The light body peeled off and many pinholes with a diameter of about 0.1 to 0.3 mm were generated. On the other hand, when the adhesive film was applied thickly, the phenomenon of so-called color mixing, in which phosphors of other colors were mixed in, became significant, and in either case, the shape of the phosphor picture element deteriorated.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to provide a high-quality cathode ray tube fluorescent surface with few pinholes and color mixture, and with a good pixel shape, using a photoadhesive method. The objective is to provide a method for forming

In order to achieve this purpose, the present invention forms a fluorescent surface using a panel whose inner surface has a surface roughness of 4 μm or less.

In other words, as a result of a detailed study of the method of forming the fluorescent surface of a color receiver tube using the conventional optical adhesive method, the above-mentioned problems were solved.
It became clear that this was caused by the rough inner surface of the panels used. Generally, from the standpoint of photosensitive properties, the thickness of the photoadhesive film is approximately 0.2 to 0.8 .mu.m. In contrast, panels conventionally used to form fluorescent surfaces have an inner surface roughness of 4 to 10 μm, and when an extremely thin film as described above is applied to such a rough surface, it is difficult to obtain a uniform film thickness. It is difficult to obtain such a film, and the film thickness varies greatly within a small range. That is, the inner surface of the panel is thicker in concave portions and thinner in convex portions. As a result, the adhesive strength becomes uneven, causing the problems described above. To be more specific, if the adhesive film is generally thin, it becomes thinner and thinner at the convex parts, and the amount of adhesive substance produced is too small, resulting in insufficient adhesive strength and a sufficient amount of adhesive material. Pinholes are more likely to occur in rounded areas to which the light powder does not adhere. On the other hand, if the adhesive film is generally thick, the adhesive substance generated especially in the recesses will be excessive. As the substance bleeds out, the phosphor powders of the first and second colors adhere to each other, causing color mixing. In addition, the decomposition is faster in thinner parts and slower in thicker parts, resulting in a difference in sensitivity.
As a result, the contours of the phosphor picture elements are disturbed, resulting in so-called shape defects.

Therefore, in order to prevent such problems from occurring, it is effective to reduce the surface roughness of the inner surface of the panel, and as a result of experiments, it has been found that this surface roughness can be reduced to an average roughness Rz value of approximately 4μ or less. It was confirmed that good results could be obtained. In addition,
Although better results were obtained by making the surface roughness as fine as possible, this is disadvantageous in terms of panel manufacture, press die life, and defect occurrence rate. Therefore, it is more preferably about 1 to 3 microns.

Specific examples will be described below.

A photo-adhesive composition having the following composition was applied to the inner surface of the panel of a 10-inch color tube, and dried to an average thickness of about 0.
．． A 5 μm photoadhesive film was formed. At this time, the panel used had an inner surface roughness of approximately 2 μm.

P-diazodimethylanili chloride Zinc chloride 3% by weight Alginate a ? 'Lengelicol ester 0.4% by weight Polyvinyl alcohol 0.07% by weight 1 Ethylene glycol 0.02% by weight Pluronic L-
92 (trade name, surfactant) 0.005 weight - weight ammonium tetramate 0.007 weight % water
Next, a shadow mask was attached to this panel, and after death, the inner part of the green luminescent phase was exposed on an exposure table. Exposure condition is illuminance 50
The exposure time was 120 seconds. After exposure, edge phosphor powder is applied to the inner surface of the panel and adhered to areas that have become sticky due to exposure, and then excess phosphor powder applied to unexposed areas is removed using air spray. did. The current salary pressure at this time is about IKt~.

Next, in the same manner, a real phosphor and a red phosphor were sequentially attached to each light emitting portion on the inner surface of the panel to form a phosphor surface consisting of three color phosphor stripes.

Compared to a phosphor surface formed in the same way using a conventional panel with an inner surface roughness of about 6 μm, the phosphor surface formed in this way is more susceptible to local peeling of the phosphor and fluctuations in film thickness. The stripe shape was also good, with less color mixing and color mixing.

Although the above explanation has been made using the case of forming a fluorescent surface of a color picture tube as an example, the present invention is not limited thereto, and can be applied to other cathode ray tube fluorescent surfaces using the photoadhesion method. It goes without saying that the same applies to formation.

As explained above, according to the present invention, it is possible to form a high-quality cathode ray tube fluorescent surface without pinholes, with little color mixture, and with a good shape of the phosphor line elements. It has a good effect.

Representative Patent Attorney Toshiyuki Usuda l-“1 To t・1 ζ　,,’,−1

Claims (1)

[Claims] a step of applying a photoadhesive composition that develops paper tackiness upon exposure to light on the inner surface of the panel and drying it to form a photoadhesive film; a step of exposing the photoadhesive film to make the exposed area tacky; A cathode ray tube comprising the steps of applying phosphor powder on the optical adhesive film and further adhering the phosphor powder to the sticky area, and removing excess phosphor powder using a 3J machine. A method for forming a fluorescent surface of a cathode ray tube, characterized in that the panel uses a panel having an inner surface roughness of 4 or less.