JPS6276238A - Method of forming phosphor surface - Google Patents

Abstract

PURPOSE:To prevent fall-off of phosphor with a simple method by applying phosphor particles to an adhesive photo-resist thin film and attaching thermoplastic resin powder on the surface, then heating the powder to fill the space between the phosphor particles. CONSTITUTION:Photoresist thin film formed on a face plate substrate is exposed to light through a shadow mask to render it adhesiveness selectively. Then phosphor particles are applied to the surface on which thermoplastic resin powder such as polyethylene is further attached by means of air spray or the like. Then it is heated to soften the polyethylene powder and fill the space between the phosphor particles and level the uneveness on the phosphor particle layer, in order to form the phosphor surface of a cathode ray tube. By this process, bonding strength between the phosphor particles and between the face plate substrate and the phosphor particles can be increased, and fall-off of phosphor can be prevented by a simple method which does not include photographic fixing process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cathode ray tube, and more particularly to a method for forming a phosphor screen using photoadhesion.

[Technical background of the invention and its problems]

A method of forming a phosphor screen of a color cathode ray tube using photoadhesion is proposed, for example, in Japanese Patent Publication No. 57-20651.

In this method, a photoresist that becomes sticky when exposed to light is first applied to the inner surface of the face plate of the cathode ray tube, and then ultraviolet rays are irradiated onto this photoresist film through a shadow mask with many through holes to make it stick in place. Give it sex. Next, phosphor particles are scattered on this adhesive photoresist film to selectively adhere only to the adhesive portions, thereby forming a phosphor particle layer on the inner surface of the face plate. In the case of a color cathode ray tube, the steps from UV irradiation to phosphor particle dispersion are repeated for the three color phosphors of blue, green, and red.Finally, the phosphor is fixed, and the phosphor particle layer is immobilized, that is, it is transferred to water. The aim is to make it insolubilized so that it can withstand the later filming process.

There are generally two types of this filming process: an emulsion method and a lacquer method. The former method involves applying an aqueous solution of acrylic emulsion to the inner surface of the face plate on which the phosphor particle layer has been deposited and drying it to form a film, while the latter lacquer method involves pre-impregnating the phosphor particle layer with water. Keep it
This method involves applying a non-aqueous lacquer solution over the surface.

In any case, according to the conventional photoadhesive method, in order to withstand the filming process, a fixing process is required after the phosphor particles are attached. This powder coating layer is usually fixed by contacting with steam containing ammonia gas, or by keeping it in a humid atmosphere and then drying it. There is a problem of deterioration9
Both methods have problems such as long processing time, uneven fixing, and insufficient adhesion.

[Purpose of the invention]

The present invention has been made in order to solve the above problems, and provides an extremely effective phosphor screen forming method that eliminates the need for a troublesome fixing process and simultaneously forms a film required in a subsequent process. It is.

[Summary of the invention]

The first aspect of the present invention is to apply a photoresist thin film that becomes sticky by light irradiation onto a face plate substrate, and to selectively irradiate light onto the photoresist thin film so as to selectively make it sticky. A layer of phosphor particles having a predetermined pattern on an adhesive photoresist thin film and a resin powder compatible with the phosphor particles are heated, softened, and then cooled to form a bond between the phosphor particles and between the face plate substrate and the phosphor particles. This method of forming a phosphor screen includes a step of increasing adhesive strength.

After adhering to the cloth, the process of heating the thermosensitive resin to strengthen the adhesion between the phosphor particles and between the face plate substrate and the phosphor particles is repeated for each of the blue, green, and red phosphors. Surface forming force ff1T, tz6.
7.Thirdly, the characteristic of applying a thermoflexible resin to the surface of the phosphor particles in advance is to further improve the adhesion between the phosphor particles and between the phosphor particles and the face plate. It is inserted into gaps or fills recesses on the surface of the phosphor particle layer, and it is desirable that the average particle size is equal to or smaller than the average particle size of the phosphor particles. The next step is to melt or soften the material at a heating temperature as low as possible to generate adhesive strength. Specifically, polymer powders such as polyethylene and polystyrene are preferred.

Specifically speaking, as an application example of the thermoplastic resin powder, in the first method mentioned above, there is, for example, a spray method, in which physical adsorption or This is a method of adhesion using electrostatic force. In the second case above, if the particle size of the thermoflexible resin powder is equal to or less than that of the phosphor particles and the specific gravity is 0.7 or less than that of the phosphor, the above-mentioned gaps and recesses can be filled. be able to. It is presumed that this is because larger and heavier particles are selectively captured by the adhesive portion.

1st. In the case of the second method, fine particles of silicon oxide (SiO□) are added to the resin powder in advance in order to apply it uniformly.

It is preferable to improve fluidity by coating with alumina (A9.03) or the like. After coating the resin powder on the phosphor particle coating layer, heating the resin with a heater or air to near the melting point where adhesive force is generated will improve the adhesive force between the phosphor particles and to the face plate substrate. Even if the conventional fixing process is omitted, the water resistance required during the filming process can be obtained. Furthermore, since the softened or melted resin powder closes the four parts, it becomes possible to perform aluminum vapor deposition and metal backing without performing a filming process. In other words, the fixing process and the filming process can be easily and accurately performed at the same time.

Furthermore, the above 2. In the case of the third method, the effect of preventing color mixture can also be achieved at the same time by heating each time the phosphor particles of each color are deposited.

[Embodiments of the invention]

(Example 1) A thin film of Photo-Resist 1, which becomes sticky when irradiated with light, was applied to the face plate substrate of a color cathode ray tube, and the thin resist film was selectively irradiated with light to make it sticky, and then the stickiness was removed. Using the so-called photoadhesion method, in which phosphor particles are attached onto a resist film, the average particle size is 5 to 7 tI!
Apply each color of blue, green, and red phosphor in a. The average particle size is 5μ from the top of the phosphor particle layer formed on this resist thin film.
s, polyethylene powder with a specific gravity of 0.8 was air sprayed for about 2 seconds. Next, the outflow of the powder was stopped, leaving only about 2 pieces of air. Next, the surface of the phosphor particle layer where the polyethylene particles remained was heated to a temperature of about 120°C. Due to this heating, the polyethylene particles melt and become adhesive, and enter into the gaps between the phosphor particles or fill all four parts of the surface of the phosphor particle layer. The adhesive force with the phosphor particles was improved, and the phosphor particles did not peel off in subsequent steps, making fixing treatment unnecessary. In addition, since the surface of the phosphor particle layer was also a smooth surface with no irregularities, aluminum could be vapor-deposited thereon to form a metal bank layer without the need for filming.

(Example 2) In the same manner as in Example 1, phosphor particles of each color were attached on the photoadhesive resist film of the face plate substrate by the photoadhesive method, and then polyethylene particles were coated on top of the particles, and after heating,
0.2k for removing unreacted resist and rewetting
Water was sprayed for 10 seconds at a pressure of g/a, then lacquered and filmed.

No phosphor particles were observed to fall off. Thereafter, aluminum was deposited to form a metal back film. A product equivalent to Example 1 was obtained.

(Example 3) A photo-adhesive resist thin film is coated on a face plate substrate, and the resist thin film is exposed to light through a shadow mask having a large number of through holes drilled in a predetermined pattern to selectively generate tackiness and reduce the average grain size. Blue phosphor with a diameter of 6 μs and an average particle size of 5
μs, 1w of blue phosphor polyethylene powder with specific gravity 0.8
t% of the mixture was mixed and spray coated onto a sticky resist film. Thereafter, the surface was heated to about 100°C. After cooling, the second color green phosphor and the third color red phosphor were subjected to the same process as the first color from exposure to cooling to form a phosphor pattern. moreover.

A film was formed by spraying water at a pressure of 0.2 kg/cJ for 10 seconds, followed by spraying with a backer, and aluminum was evaporated thereon to form a metal back film. In this example, no phosphor particles were observed to fall off, and a good phosphor screen was formed. In addition, good level quality was achieved when mixing green and red phosphors into the blue phosphor layer and mixing red phosphor into the green phosphor layer.

(Example 4) In the same manner as in Example 3, after applying polyethylene powder, aluminum evaporation was performed directly without filming to form a metal back film, and it was possible to obtain almost the same product characteristics.

(Example 5) A phosphor pattern was formed by a photoadhesion method using a phosphor whose surface was coated with 0.5 wt % of 0.5 wt % polyethylene powder on the surface of the phosphor. After applying the phosphor particles of each color, a heat treatment was performed to about 100°C. In this case as well, there was no need for a separate fixing process, the phosphor particles did not fall off even after washing with water during the filming process, and an improvement in the level of color mixing was observed.

〔Effect of the invention〕

As described above, according to the present invention, in a method for forming a phosphor screen using a photoadhesive method, it is possible to prevent the phosphor from falling off using a simple method that does not involve a fixing process, and it is also possible to improve the quality of color mixing.

Agent: Patent Attorney Noriyuki Chika Same Norio Ogo

Claims (3)

[Claims] (1) A process of applying a photoresist thin film that becomes sticky when irradiated with light on the face plate substrate, a process of irradiating light to selectively make it sticky on this photoresist thin film, and a process that makes it sticky. A step of attaching thermoplastic resin powder to a layer of phosphor particles having a predetermined pattern on the photoresist thin film so as to fill the gaps between the phosphor particles and the irregularities on the surface of the phosphor particle layer, heating the thermoplastic resin powder, A method for forming a phosphor screen, comprising at least the step of cooling the phosphor particles after softening to enhance adhesion between the phosphor particles and between the face plate substrate and the phosphor particles. (2) A method for forming a phosphor screen according to claim 1, wherein a mixture of phosphor particles and thermoplastic resin powder is dispersed and adhered onto a photoresist thin film having adhesive properties. (3) The method for forming a phosphor screen according to claim 1, wherein the surface of the phosphor particles is coated with a thermoplastic resin in advance.