JPH0215533A - Manufacture of cathode ray tube - Google Patents

Abstract

PURPOSE:To aim at decreasing the emission gas quantity generated by thermal and electron beam irradiation by adding the heat treatment of the specific temperature to the film formed on the surface of a shadow mask by spraying the mixture of heavy metal oxide powder and binder. CONSTITUTION:1 weight part of heavy metal oxide and desirably about 0.6-0.8 parts of demineralized water are mixed, and 0.2-0.4 parts of the binder composed of sodium water glass or potassium water glass are added to this mixture for rolling. The obtained mixture is applied on the surface side of electron beam irradiation of a shadow mask 3 by means of a spraying method. In this case, the thickness of an electron beam reflection film 7 is made such that electron beam does not penetrate. The shadow mask 3 is put into a furnace such as a drying furnace of 80-150 deg.C, desirably 120 deg.C and heat treated in the air, nitrogen or oxygen atmosphere. The film becomes scientifically stable by this treatment, the emission gas quantity generated by thermal and electron beam irradiation is largely decreased, and the emission life characteristic of cathode is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a cathode ray tube having a shadow mask. The present invention relates to a method of manufacturing a cathode ray tube to reduce the amount of gas.

[Conventional technology]

FIG. 1 is a sectional view of a conventional cathode ray tube disclosed in, for example, Japanese Unexamined Patent Publication No. 55-76553. In Fig. 1, 1 is an envelope for keeping the inside in a high vacuum, 2 is an electron gun for emitting three electron beams, 3 is a shadow mask that constitutes a color selection electric bridge, and the electron beam A heavy metal oxide coating w17 made of a material having a high reflectance with respect to the electron beam is provided on the surface where the electron beam collides. 4 is a translucent glass front plate that constitutes a part of the envelope 1, and 5 is a fluorescent screen, which is red.

Three types of phosphor stripes that emit green and blue light are sequentially coated on the inner surface of the glass front plate 4, and each of these stripe groups corresponds electro-optically accurately to each of the slit groups of the shadow mask 3. They are located in such a positional relationship that Reference numeral 6 denotes an internal magnetic shield plate, 8 a deflection cork for horizontally and vertically deflecting the three electron beams, and 9 a getter for maintaining a high vacuum inside the shade tube. FIG. 2 also shows a shadow mask 3. which is the main part of the apparatus shown in FIG. Glass front plate 4
．． Fluorescent screen5. FIG. 7 is an enlarged view of the electron beam reflective coating 7. FIG.

Next, the operation of the cathode ray tube will be explained.

Three electron beams emitted from the electron gun 2 are deflected by a deflection yoke 8 so as to scan the entire surface of the fluorescent screen 5 and reach the shadow mask 3.

This shadow mask 3 has a color selection function that allows the three electron beams to hit only the phosphor stripes of the respective colors. The positions of the slit group and the phosphor stripe group are set accurately electro-optically.

Therefore, the electron beam passing through the slits of the shadow mask 3 hits only the phosphor stripes of the respective colors, causing them to emit light. At this time, if the intensity of the three electron beams is changed by an electric signal applied to the control electrode of the electron gun 2, the luminance of each phosphor stripe can be changed, and the color can be changed as desired. A color image is displayed.

However, in this case, approximately 80% of the electron beam emitted from the electron gun 2 collides with the shadow mask 3 and is blocked, giving completely meaningless thermal energy to the shadow mask 3 and raising the temperature of the shadow mask 3. . the result,
The shadow mask 3 is deformed due to thermal expansion, and the positional relationship between the shadow mask 3 and the phosphor stripes, which had been accurately corresponding to each other, is shifted, which becomes a major cause of color shift.

As a means of solving these problems,
In Japanese Patent Publication No. 60-14459, it is disclosed that a coating 7 made of a material having a higher electron beam reflectance than the material constituting the shadow mask 3 is provided on the electron beam irradiation surface of the shadow mask 3, and Japanese Patent Publication No. 14459/1983 It has been proposed to provide a coating 7 that reflects the electron beam by spraying a solution containing a heavy metal material having an atomic number exceeding 70, and the heavy metal material includes lead, tungsten,
and bismuth, and the usefulness of their carbides, sulfides, and oxides is also discussed.

When manufacturing a cathode ray tube using a shadow mask provided with a film as disclosed in Japanese Patent Publication No. 14459/1980, the average particle size of the fine particles must be 1 pm or less when using any heavy metal material. For example, when bismuth oxide is selected as the coating material, particles with a large particle size of about several to several tens of sizes are usually pulverized and used.

The ball milling method is usually used as a crushing method, and during ball milling, bismuth oxide powder, water glass, and an appropriate amount of water are added at the same time, ball milling is performed for about 2 to 7 days, and then an appropriate amount of water glass and water is added again to coat the shadow mask. After coating and air drying, it is obtained through the normal manufacturing process of cathode ray tubes.

[Problem to be solved by the invention]

The conventional manufacturing method for cathode ray tubes is constructed as described above, and the heavy metal oxide coating 7 is formed by spraying a mixture of heavy metal oxide powder and water glass. Coating 7 caused by heating and electron irradiation during operation
There is a problem in that the amount of gases (Co and COt gas, etc.) released from the cathode ray tube increases, strongly poisoning the cathode of the cathode ray tube, reducing the emission life characteristics of the cathode, and shortening the life of the cathode ray tube.

The present invention has been made to solve the above problems. In other words, the heavy metal oxide film reduces the amount of gas emitted by heating and electron irradiation during operation of the cathode ray tube, maintains good emission life characteristics of the cathode, and provides a method for manufacturing cathode ray tubes with a long life. The purpose is to obtain.

[Means to solve the problem]

The method for manufacturing a cathode ray tube according to the present invention is to apply heat treatment at 80°C to 150°C to a film formed on a shadow mask surface by spraying a mixture of heavy metal oxide powder and a binder. .

[Effect]

In the present invention, the film on the shadow mask surface is heat-treated at 80°C to 150°C immediately after application, making it chemically stable and greatly reducing the amount of total carbonate produced by the binder components. This greatly reduces the amount of gas released due to thermal and electron beam irradiation during operation of the cathode ray tube, and in cathode ray tubes with such heat-treated coatings, poisoning of the cathode is reduced. It is possible to maintain good emission life characteristics and extend its life.

〔Example〕

Table 1 shows the variation in the total carbonate production amount depending on the drying temperature. That is, B it Ox 30g, water glass 7.
Shadow Mask 3 with a standard composition of 5g and 19g of pure water.
Immediately after coating, the drying temperature was set to room temperature, 50°80, 1
20. The results of measuring the total carbonate production amount by infrared spectroscopy when changing the temperature to 150°C are shown.

Table 1. Drying temperature and total carbonate amount The total carbonate amount was determined by applying the baseline method to the infrared absorption spectrum of the sample shown in Figure 3, and assuming the absorbance of water glass (~1050 as-') to be 1. 1400cm
The relative absorbance of the C-O asymmetric stretching absorption band around -' is determined.

According to Table 1, the total amount of carbonates is large at drying temperatures up to 50°C, but decreases at drying temperatures of 80°C or higher;
In order to produce cathode ray tubes with excellent life characteristics, where the difference between
It is clear from Table 1 that ~150°C is preferred.

An embodiment of the method for manufacturing a cathode ray tube according to the present invention will be described below.

Preferably, about 0.6 to 0.8 parts of pure water are mixed with 1 part (by weight, the same applies hereinafter) of the heavy metal oxide powder, and the mixture is mixed for about 3 days using a ball mill method or the like. 0.2 to 0.4 parts of a binder such as sodium water glass or potassium water glass is added to this mixture and rolled for about one day.

The obtained mixture is applied to the electron beam irradiation surface side of the shadow mask 3 by a conventional spraying method such as an air spray method. Note that the electron beam reflective coating 7
The thickness is preferably such that the electron beam does not pass through it, and the thickness after heat treatment is usually about 2 to 57,111 mm.

Further, the shadow mask 3 used in this embodiment may be one conventionally used in cathode ray tubes.

This shadow mask 3 is heated at 80 to 150°C, preferably at 1
The material is placed in an oven such as a drying oven at 20° C., and heat-treated for about 5 to 30 minutes in air, nitrogen, or oxygen atmosphere.

If the temperature of the furnace is less than 80° C., the target II 7 will be insufficiently dried, resulting in insufficient gas release, which will adversely affect the emission life characteristics of the cathode.

For example, a case in which the electron beam reflective coating 7 made of a mixture of bismuth oxide powder and potassium-based water glass is subjected to a drying process at 120° C. will be specifically described below.

First, 3000 g of bismuth oxide pulverized to an average particle size of 111 m or less by a ball mill method and 1900 g of pure water were mixed for 3 days by a ball mill method, and 750 g of potassium water glass was added to this mixture and rolled for about 1 day.

A coating liquid made of the obtained mixture was applied to the electron beam irradiated surface side of the shadow mask 3, which had been subjected to the blackening treatment, by air spraying to form an electron beam reflective coating 7. Immediately after forming the coating 7, this shadow mask 3 is placed in a drying oven at 120° C. in air for 25 minutes, and then put into a normal cathode ray tube manufacturing process to produce a 21-inch color cathode ray tube with a 90° deflection. was manufactured.

Next, we will discuss the results of examining the emission life characteristics of the cathode of the obtained cathode ray tube.

Electron beam current 0.9 mA, electron beam acceleration voltage 25
kV.

When measuring the emission depreciation life characteristics of the cathode at a heater voltage of 6.3 V, the life characteristics of the maximum emission current of the cathode ray tube using Shadow Mask 3 obtained by the above manufacturing method are higher than those of a conventional cathode ray tube of the same shape. A good result of about 20% increase was obtained.

In other words, the electron beam reflective coating 7 that has been dried at 120°C becomes chemically stable, and the amount of total carbonate produced by the binder component (potassium water glass) is greatly reduced, so that it is stable during operation of the cathode ray tube. The amount of gas (Cot, Co, Ox gas, etc.) released from the coating 7 due to thermal and electron beam irradiation was significantly reduced, and the poisoning of the cathode was reduced.

Therefore, the emission life characteristics of the cathode were maintained better than in the past, and the life of the cathode ray tube was extended by approximately 20%.

In the above embodiment, bismuth oxide is used as the material constituting the reflective coating 7, but this is a material that has a high electron beam reflectance and has a higher density or a larger atomic number than the material constituting the shadow mask 3. Other heavy metal oxides may be used as long as they contain the element.

〔Effect of the invention〕

As described above, according to the method for manufacturing a cathode ray tube according to the present invention, the electron beam reflective coating formed on the shadow mask surface is subjected to a drying process at 80 to 150°C.
The coating is chemically stable, and the amount of gas emitted from the electron beam reflective coating due to heating and electron beam irradiation during cathode ray tube operation can be significantly reduced, and the cathode has good emission life characteristics. This has the effect of preventing the life of the cathode ray tube from being shortened.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a shadow mask type cathode ray tube, FIG. 2 is an enlarged view showing the main part thereof, and FIG. 3 is a diagram showing an infrared absorption spectrum of a sample. 3... Shadow mask, 4... Glass front plate, 5...
... Fluorescent screen, 7... Electron beam reflective coating. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A mixture of heavy metal oxide powder and a binder is sprayed onto the shadow mask surface to form a film, and the film is
A method for manufacturing a cathode ray tube, comprising forming an electron beam reflective coating on the shadow mask surface by applying heat treatment at 0°C to 150°C.