JPS6310531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for forming a phosphor surface of a color picture tube by a so-called dry process in which a phosphor is applied in a powder state to a face panel.

The phosphor surface of a color picture tube consists of three-color phosphor films coated in dots or stripes at predetermined locations. However, a method is already known in which a predetermined portion of a film is exposed to light through a shadow mask and the photoreaction that occurs there is used to form the film.

That is, a photosensitive film is formed by coating the inner surface of the face panel with a photosensitive resin mainly composed of diazonium salt, and when the parts of this photosensitive film where the phosphor is to be coated are exposed to light, the phosphor is applied to the inner surface of the face panel. The zinc chloride produced in the exposed areas absorbs moisture from the atmosphere and becomes sticky, so spraying phosphor powder of a predetermined luminescent color onto the inner surface of the face panel can reduce the stickiness of the photosensitive film. This phosphor powder will adhere to only the exposed areas and the phosphor will be coated. After performing this process of spraying the phosphor powder and applying adhesive to each of the three primary light phosphors, ammonia gas is applied to the photosensitive film to expose the areas where the phosphor powder has been adhesively applied. The fluorescent surface is formed by fixing the transparent film as being insoluble in water, and then washing out excess residue with an organic solvent.

This method is a type of so-called dry process.
Compared to the conventional method in which each color phosphor is made into a photosensitive slurry and sequentially coated, exposed, and washed and developed, the photosensitive film can be formed only once, which shortens the work process. There are advantages such as being economical because the light material can be sprayed in powder form and the unnecessary portion that does not adhere to the adhesive part can be blown away and recovered in powder form with an air spray.

However, in this method, there is a problem in that the phosphor of another color in the next step adheres to the edge of the phosphor coated in the previous step. That is, in the step of forming a phosphor film of the first color, the exposed area absorbs moisture in the air to become sticky, and the phosphor powder of the first color is attached thereto. Since the adhesive film itself is water-soluble, moisture absorbed in the exposed areas of the film seeps out to the outside of the exposed areas, causing these areas to become sticky. Therefore, in the next step of forming a phosphor film of the second color, when applying the phosphor powder of the second color to the exposed area after exposure, the area where the phosphor of the first color was applied is The phosphor powder of the second color adheres to the outer edge. Similarly, in the third color phosphor film forming step, the third color phosphor powder adheres to the outer edges of the areas where the first and second color phosphors are coated. As described above, when a so-called fogging phenomenon occurs, in which phosphor powder adheres to unexposed areas due to seepage of moisture, the color purity of the color picture tube deteriorates. This fogging phenomenon is relatively less of a problem in the case of a black matrix type in which the spaces between the phosphor films are filled with black, but this fogging phenomenon becomes a particularly serious problem in the general type in which the spaces between the phosphor films are not filled in with black.

The present invention was made in order to eliminate such conventional drawbacks, and its purpose is to prevent the previously applied phosphor from causing fogging due to phosphors of other colors, and to improve color purity. It is an object of the present invention to provide a method for forming a fluorescent surface of a color picture tube, which can improve the quality of the color picture tube.

To achieve this purpose, the effective relative humidity in the process of depositing the second color phosphor powder is not lower than the effective relative humidity in the process of depositing the first color phosphor powder. , and the effective relative humidity in the step of depositing the third color phosphor powder is set to be equal to or lower than the effective relative humidity in the step of depositing the second color phosphor powder.

That is, as a result of conducting various experiments to achieve the above-mentioned purpose, it was found that the amount of moisture absorbed by zinc chloride generated by the reception of light by the diazonium salt is proportional to the relative humidity and the weight of the photosensitive film, and that the relative humidity is low. In this case, the moisture absorbed in the exposed areas of the photosensitive film does not seep into the unexposed areas, and the effective relative humidity of the photosensitive film is easily controlled by the temperature of the face panel, regardless of the relative humidity in the air. Since it was confirmed that this could be done, the effective relative humidity of the photosensitive film on the inner surface of the face panel was gradually reduced in each process of the first, second, and third colors. It is.

Hereinafter, the present invention will be explained in detail with reference to Examples.

First, 0.6 wt% of alginate propylene glycol ester, 3.0 wt% of P-N-N dimethylaminobenzenediazonium zinc chloride, 0.003 wt% of Pluronic L-92 (oxyethylene oxypropylene block copolymer), and water. Prepare a photosensitive resin solution mixed with the remaining ingredients.

Then, under indoor environmental conditions of a temperature of 25°C and a relative humidity of 50%, the solution is uniformly applied to the inner surface of the face panel of a 14-inch color picture tube to a thickness of 0.6 to 1.0 μm, and dried to form a photosensitive film. do. Next, after lowering the temperature of the face panel to 23℃, a shadow mask is combined with the face panel, and the green phosphor of the photosensitive film is exposed to light with an intensity of 15 to 20 W/ ^m2 for 2 to 3 minutes through this shadow mask. The areas to be coated are irradiated and exposed. As a result of this exposure, the diazonium salt decomposes in the exposed areas of the photosensitive film to produce zinc chloride, which further absorbs moisture in the air and becomes sticky. It is generally known that relative humidity decreases or increases by approximately 3% when the temperature increases or decreases by 1°C. Therefore,
When the face panel is maintained at 23°C, the photosensitive film is also at 23°C, so its effective relative humidity is 56%. Here, when a green phosphor powder is sprayed onto the photosensitive film and then air-sprayed, 3.2 to 3.4 mg of this phosphor powder is applied to only the exposed areas of the photosensitive film that have become sticky. Approximately ² cm of adhesive adheres.

Here, since the temperature of the face panel was initially lowered by 2° C. from room temperature, it gradually rose over time. When the temperature of the face panel reaches 24°C, the effective relative humidity of the photosensitive film has decreased to 53%. The temperature of this face panel is 24℃
When the temperature has reached the point where the blue phosphor is to be applied, the areas of the photosensitive film to which the blue phosphor is to be applied are irradiated and exposed under the same conditions as above. Next, when a blue-colored phosphor powder is sprayed onto the photosensitive film and then air-sprayed, about 3.1 to 3.3 mg/cm ² of this phosphor powder adheres only to the exposed areas. At this time, the effective relative humidity of the photosensitive film is 3% lower than in the green previous process, so the water absorbed in the previous process does not seep from the exposed areas to the unexposed areas, and the green fluorescent light is absorbed. There is no blue phosphor powder attached to the outer edge of the body membrane.

Next, when the temperature of the face panel reaches the room temperature of 25° C., the areas of the photosensitive film where the red phosphor is to be applied are irradiated and exposed under the same conditions as above. Then,
When red-colored phosphor powder is sprayed onto a photosensitive film and then air-sprayed, approximately 3.0 to 3.2 mg/cm ² of this phosphor powder adheres only to exposed areas.
At this time, the effective relative humidity of the photosensitive film is 50%, which is 3% lower than in the blue previous process, so the moisture absorbed in the previous process seeps from the exposed areas to the unexposed areas. There is no possibility that the red phosphor powder will adhere to the outer edge of the blue phosphor film.

In the above example, the process was started by lowering the face panel by 2°C from room temperature, but the process for the first color was carried out with the indoor environmental conditions at a temperature of 25°C and a relative humidity of 56%, and then the face panel was heated to 26°C. The second color process is performed by heating to bring the effective relative humidity of the photosensitive film to 53%, and then the second color process is performed by heating the face panel to 27°C to bring the effective relative humidity of the photosensitive film to 50%. It is also possible to gradually raise the temperature of the face panel from room temperature so as to perform the third color process.

Furthermore, it goes without saying that the same effect can be obtained by directly changing the environmental conditions without changing the temperature of only the face panel.

In addition, in order to carry out each of the above Examples effectively, it was confirmed that a temperature range of 20 to 30°C and a relative humidity range of 49 to 61% are appropriate. Relative humidity is 49%
If it is less than 61%, the moisture in the air will not be absorbed sufficiently in the exposed area and adhesiveness will not be obtained.If it is more than 61% and there is too much moisture in the air, the relative humidity will be lowered in the process as described above. However, it becomes impossible to suppress the fogging phenomenon.

As described above, according to the color picture tube fluorescent surface forming method according to the present invention, the previously applied phosphor is prevented from being fogged by the phosphors of other colors, and the three colors can be formed using a simple process. Since the phosphor can be formed in an accurate position, it has the effect of improving the color purity of the color picture tube.

Claims (1)

[Claims] 1 After coating a face panel with a photosensitive resin film containing diazonium salt as its main component, the parts of the photosensitive resin film where the phosphor is formed are exposed to light, and these parts become sticky due to photoreaction and moisture in the atmosphere. The phosphor powder is attached to the exposed area using its adhesive property, and the process of coating the phosphor is performed sequentially to form a phosphor film of three colors. In the color picture tube phosphor surface forming method described above, the effective relative humidity in the process of depositing the phosphor powder of the second color and applying the phosphor is controlled by adjusting the effective relative humidity of the phosphor powder of the first color. The effective relative humidity in the step of applying the phosphor powder and applying the phosphor powder of the third color is not more than the effective relative humidity of the second color. 1. A method for forming a phosphor surface of a color picture tube, characterized in that the relative humidity is lower than the effective relative humidity in the step of applying phosphor powder and coating the phosphor.