JPH04328225A - Color cathode ray tube of black matrix type - Google Patents

Abstract

PURPOSE:To construct a color cathode ray tube of black matrix type, which is free from rough surface sense on the screen, provides good picture quality, and presents a sufficient contrast. CONSTITUTION:A color cathode-tube of black matrix type is made with a material at least containing Si carbide in the form of super-perticulates as a photo-absorbing material for use in the black matrix 12. This eliminates substantially oxidative wear and loss in the heating process in manufacture of cathode ray tube, and a black matrix excellent in the photo-absorbing characteristics is accomplished.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a black matrix type color cathode ray tube, and more particularly to a black matrix type color cathode ray tube that is free from roughness and can provide a picture screen with good contrast.

0002

2 is a diagram showing a schematic structure of a black matrix type color cathode ray tube, and FIG. 1 is a diagram showing a schematic structure of a black matrix type color cathode ray tube phosphor screen. , a suspension made by finely pulverizing natural flaky graphite or artificial graphite as a light-absorbing material, adding a binder, and dispersing it in water;
Alternatively, a slurry in which carbon black and artificial graphite as light absorbing materials are dispersed using a protective colloid of a water-soluble polymer such as polyvinyl alcohol has been used. Further, as described in Japanese Patent Laid-Open No. 62-157647, an image display device using partially graphitized carbon black particles as a light absorbing material has been disclosed. However, a black matrix that uses graphite as a light absorption material has an average reflectance of external light of around 3%, and the reflected color is blackish brown, so it is not always possible to obtain sufficient image contrast, and the texture is poor. It had the disadvantage of being inferior.

In addition, in recent years, as color cathode ray tubes have become finer pitched, larger, and have higher contrast, conventionally used graphite has had the following disadvantages, making it difficult to cope with them. In other words, as the pattern of stripes or dots constituting the black matrix becomes smaller as the pitch becomes finer, the sharpness of the pattern is lost due to the larger particles of graphite used in the past, leading to a decrease in image quality. (The screen appears grainy)
To deal with this, if the particles are made finer, their heat resistance decreases and they are oxidized and depleted during the heating process at around 450°C during the manufacture of cathode ray tubes, resulting in a decrease in light absorption ability (large color cathode ray tubes have a large heat capacity, so this phenomenon occurs). In particular, there were problems such as acceleration. In addition, in normal cases, graphite is 60
Polyvinyl alcohol (PVA), which is said to react with oxygen at temperatures between 0 and 700°C, is used when creating phosphor screens.
, polyvinylpyrrolidone (PVP), carboxymethyl cellulose (CMC), etc., oxidation easily proceeds at a temperature comparable to that of the heating process during the manufacture of cathode ray tubes.

0004

As described above, in the prior art, it has not always been possible to obtain a black matrix type color cathode ray tube having sufficient image quality and contrast.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and provide a black matrix color cathode ray tube that is free from roughness and has good image quality and sufficient contrast.

[0006]

[Means for Solving the Problems] The above object can be achieved by using a material containing at least fine silicon carbide powder (having an average particle size of 1 μm or less) as a light-absorbing material for a black matrix.

[0007] The above-mentioned silicon carbide includes those having a total carbon content of 29% by weight or more (black color, hereinafter referred to as carbon-containing silicon carbide). In addition to when used alone, the same effect occurs when graphite is added to silicon carbide, when graphite is added to carbon-containing silicon carbide, and when graphite is further added to a mixture of silicon carbide and carbon-containing silicon carbide. You can get results.

[0008]

[Action] Silicon carbide has excellent heat resistance even when the particle size is reduced, and it also has excellent light absorption properties, so it can exhibit excellent properties when used as a light absorption material for black matrix. . As an example, Table 1 shows the particle state, optical properties, and thermal loss rate of carbon-containing silicon carbide fine powder. In the same table, the reflected color is the reflected color when white light is irradiated, and the reflectance is the reflected color when the material is coated with a thickness of 1 μm on a barium sulfate white board base, and the wavelength is 550 nm.
The reflectance when irradiated with light of m, the thermal depletion rate is 5 in the air.
The weight loss rate when heated at a temperature of 50° C. for 3 hours is shown.

[0009]

[Table 1]

From the results shown in the above table, it can be seen that carbon-containing silicon carbide has good heat resistance and excellent reflection characteristics even if the particle size is small. In addition, exactly the same results were obtained when silicon carbide was used alone, when graphite was added to silicon carbide or carbon-containing silicon carbide, and when graphite was further added to silicon carbide and carbon-containing silicon carbide. .

[0011]

EXAMPLES The black matrix type color cathode ray tube of the present invention will be explained in detail below by way of examples.

Example 1 First, materials having the following composition were mixed and dispersed using an ultrasonic dispersion device to prepare a slurry. Carbon-containing silicon carbide fine particles
...10% by weight polyvinyl alcohol (saponification degree 88%)
… 1% by weight Colloidal silica (trade name Ludox AM) … 0.05% by weight Surfactant (trade name Demol N)
...0.01% by weight
water
… 8
8.94% by weight Next, using the above slurry, 79cm
A BM film was formed on a striped type color cathode ray tube by photolithography as usual. A photoresist mainly composed of polyacrylamide diacetone acrylamide and azide was applied to the cleaned panel and dried to a film thickness of 0.08 μm.
A photoresist film of m was formed. Next, a shadow mask was attached, and 2.0
Light was irradiated for 40 seconds at a light intensity of W/m2, and the photoresist film was exposed and cured in the portions corresponding to the green, blue, and red phosphor attachment positions. Next, add 24.52 x 10 warm pure water at 40°C.
It was sprayed at a pressure of 4 Pa to leave only the exposed and hardened portion on the inner surface of the panel, and was dried with a far-infrared heater. While rotating this panel at 10 rotations/min, the head difference is 2m.
Φ10mm vertically to the center of the panel with the pressure of
Spray the above slurry from the rod nozzle for 10 seconds,
It was shaken at 0 rotations/min for 15 seconds and dried with a far-infrared heater to form a light absorbing material layer. Next, it was treated with a hydrogen peroxide stripping solution for 80 seconds, and warm pure water was sprayed at a pressure of 34.33 x 10 Pa to remove the photoresist in the exposed and hardened area and the light absorbing material layer thereon to form a BM film. .

[0013] When comparing a BM film using fine silicon carbide powder with a BM film using conventional graphite, the BM film using conventional graphite appeared rougher and had a worse texture. Therefore, the BM film was enlarged 2000 times and the shapes of the BM stripe edges were compared. The unevenness of the BM stripe edge is 0.4 μm or less for the BM film using silicon carbide fine powder, which is 1/2 that of the conventional BM film, compared to 1 μm or less for the conventional BM film.
It was below.

After forming a phosphor layer and an acrylic resin layer on this BM film by a known method, aluminum was vapor deposited to form an aluminum thin film on the back side of the phosphor film. Next, the organic matter contained in the fluorescent film was decomposed and removed by baking at 420° C. for 1 hour. After that, the inner shield was attached and combined with the funnel coated with interior graphite and frit glass, 460
C. for 1 hour, and the panel portion and funnel portion were sealed with frit glass. An electron gun was sealed in this valve and evacuated to create a black matrix color cathode ray tube.

The characteristics of the cathode ray tube thus manufactured were compared with those of a conventional cathode ray tube using graphite. Comparative measurements were made for the light absorption ability of the panel surface, screen smoothness, and contrast for both, and the results shown in Table 2 were obtained. Here, light absorption capacity is the ratio of the light absorption rate when external light is irradiated on the panel surface, and screen smoothness is the ratio of the brightness variation for each dot when the phosphor screen is illuminated uniformly. Contrast is a number that indicates the ratio of brightness between the illuminated portion of the phosphor screen and the non-illuminated portion when external light is irradiated onto the panel surface.

[0016]

[Table 2]

Furthermore, the relationship between the film thickness and the hiding rate was investigated by changing the concentration of the light absorbing material and the number of swing-off rotations. As shown in FIG. 3, it was found that the same hiding rate as conventional graphite can be obtained with a film thickness that is approximately 1/2 that of conventional graphite. A cathode ray tube was manufactured using this film in the same manner as above, and its characteristics were compared with that of a conventional cathode ray tube using graphite. As a result, it was found that the same effect as when the silicon carbide film is thicker can be obtained.

From the above results, it can be seen that the black matrix type color cathode ray tube constructed according to the present invention exhibits much superior image characteristics as compared to the same type tube of conventional specifications.

[0019]

[Effects of the Invention] As described above, by using a material containing at least silicon carbide fine powder as a light absorbing material for the black matrix in a black matrix type color cathode ray tube, the problems of the prior art are solved. As a result, it was possible to provide a black matrix type color cathode ray tube that is free from roughness and can display an excellent image screen with good contrast.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a black matrix type color cathode ray tube fluorescent screen.

FIG. 2 is a diagram showing a schematic configuration of a black matrix color cathode ray tube.

FIG. 3 is a diagram showing the relationship between the film thickness of a light absorbing material and the hiding rate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Panel part, 2... Funnel cone part, 3... Funnel neck part, 4... Fluorescent screen, 5... Shadow mask surface, 6...
Shadow mask structure, 7... Support frame, 8... Spring, 9... Panel pin, 10... Electron beam, 11... Electron gun, 12... Black matrix, 13... Fluorescent dot, 21... When using conventional graphite, 22... Carbonization When using silicon fine powder.

Claims (1)

[Claims] 1. A black matrix type color cathode ray tube, characterized in that a material containing at least silicon carbide fine powder is used as a light absorbing material for the black matrix.