KR940005492B1 - Shadow mask and manufacturing method for the same - Google Patents

Abstract

Disclosed is a shadow mask and a fabrication method thereof, mounted in a color cathode ray tube, having functions of selecting color distinct and a doming prevention layer on the surface of the electron gun, wherein doming prevention layer is blackened and further includes an bismuth oxide, an plumbum oxide, and ferrous oxide and their chemical compound, thereby simply preventing doming by increasing heat-radiation ratio and decreasing heat-expansion ratio of the shadow mask and providing an excellent cathode ray tube with screen of high resolution.

Description

Shadow mask and manufacturing method thereof

1 is a schematic cross-sectional view of a conventional cathode ray tube,

Figure 2 is a graph showing the amount of heat drift according to the anti-domming film thickness of the conventional shadow mask (x-x) and the shadow mask (o-o) of the present invention,

3 is compared with the white reflectance (c) as the MCPD spectrum showing the degree of blackening of the anti-doping coating of the shadow mask prepared according to the conventional method (a) and the method (b) of the present invention.

* Explanation of symbols for main parts of the drawings

One; Electron gun 2; Shadow mask

3; Anti-domming film 4; panel

The present invention relates to a shadow mask and a method for manufacturing the same, and more particularly, to a shadow mask having an excellent anti-doming effect and a method for manufacturing the same.

The shadow mask is one of the most important parts of the color cathode ray tube, and has a color discrimination function that can be matched with a monochrome cathode ray tube. The shadow mask is made of high-purity low-carbon steel sheets such as rimd steel and aluminum-kilted steel, and hundreds of thousands of holes are drilled on the surface to pass each electron beam through the holes.

Typically, the shadow mask is disposed at about 10 mm in front of the fluorescent surface to have the same curvature as the fluorescent surface, and is made of a thin iron plate of about 0.15 mm having holes or slits of 0.20 to 0.25 mm.

On the other hand, about 80% of electrons emitted from the electron gun of the cathode ray tube collide with the shadow mask mounted inside the cathode ray tube. At this time, the kinetic energy of the collided electron is converted into thermal energy, thereby raising the temperature of the shadow mask.

As such, when the shadow mask is heated, a so-called "domming" phenomenon occurs in which the shadow mask swells and moves toward the screen due to thermal expansion. This swelling of the shadow mask prevents electrons from colliding accurately with the intended phosphor on the fluorescent surface. It causes a landing error.

In order to prevent the doming phenomenon, a suspension obtained by mixing heavy metal or heavy metal oxides such as bismuth (Bi), lead (Pb) and tungsten (W) with water glass or pure water is applied to the electron gun surface of the shadow mask by spraying or the like. A prevention film is formed. This is to increase the reflectance of the incident electrons so as to reduce the thermal deformation of the shadow mask. The drawback of this method is that it is difficult to blacken the film. For example, in the case of bismuth oxide, it becomes yellow, but the film which has not been blackened cannot obtain a sufficient anti-domming effect because of low heat radiation rate.

For example, Japanese Patent Laid-Open No. 64-81139 discloses an example in which an anti-doping film is formed on a shadow mask surface by mixing bismuth oxide (Bi ₂ O ₃ ) with a metal other than bismuth or a metal oxide powder other than bismuth. This eliminates the drawback of deteriorating the characteristics of cathode ray tube due to the release of CO ₂ gas due to the production of Bi ₂ O ₂ CO ₃ in the conventional method, but increases the heat radiation rate due to blackening of the film formed on the shadow mask. Couldn't.

An object of the present invention is to provide a shadow mask having a blackened anti-doming film, which can increase the thermal radiation rate of the shadow mask to reduce the thermal expansion rate of the shadow mask and effectively prevent the doming phenomenon.

Another object of the present invention is to provide a method of manufacturing the shadow mask having a hardened anti-doming film.

In order to achieve the above object, in the present invention, a shadow mask embedded in a color cathode ray tube, having a color discrimination function, and having an anti-doping film on the electron gun surface, wherein the anti-domming film is blackened, bismuth oxide (Bi ₂ O _3). ), Lead oxide (PbO) and iron oxide (Fe ₃ O ₄ ) and a shadow mask comprising a reaction compound thereof is provided.

Here, the reaction compound includes Bi ₁₂ PbO ₂₀ , Bi ₂ Fe ₄ O ₉ , PbFe ₄ O _7, and the like.

In order to achieve another object of the present invention in the present invention, in the method of manufacturing a shadow mask embedded in the cathode ray tube and having an anti-doping film on the surface of the electron gun, the anti-doming film is bismuth oxide (Bi ₂ O ₃ ), lead oxide ( PbO), spraying a suspension containing an iron-containing material, pure water, water glass, and a dispersant to the electron gun side of the shadow mask; It provides a method for producing a shadow mask, characterized in that the shadow mask is produced by the process of firing at 400 to 500 ℃.

The amount of the bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO), and the material containing iron is preferably 10 to 60% by weight based on the total amount of the suspension, of which the lead oxide and iron The amount of the mixture is preferably 1 to 30% by weight, respectively, based on the total amount of the suspension.

And the material containing the iron can obtain an excellent effect when any one of iron element or iron oxide (Fe ₃ O ₄ ), the particle diameter of the material containing bismuth oxide, lead oxide, iron is 0.1 to 2.0㎛ It is preferable.

In the present invention, in the manufacture of the suspension sprayed for the anti-domming in the shadow mask mounted inside the cathode ray tube, the bismuth oxide powder to include a powder of a material containing a lead oxide powder and iron in each of the following firing process By using the properties of blackening of the elements to form a compound, not only the reflection effect of the electron beam by heavy metals but also the effect of increasing the thermal radiation by blackening is lowered the thermal expansion rate of the shadow mask and minimized the dominant phenomenon.

The shadow mask of the present invention is prepared according to the following method.

First, dissolve an appropriate amount of lignin-based dispersant in pure water, add water glass to it, and uniformly mix it. Then, mix a predetermined amount of bismuth oxide powder, lead oxide powder, and powder of iron in this solution. Mix evenly.

In this case, the iron-containing material is an iron element or iron oxide, and the mixed amount of lead oxide is 1 to 30% by weight, respectively, based on the total amount of the suspension. If the amount of the powder is less than 1% by weight, the film blackening property is significantly reduced. If the amount of the powder is more than 30% by weight, the film is easy to blacken, but since the electron reflection efficiency is lowered, the thermal expansion rate of the shadow mask is increased so that the anti-doming effect is not properly obtained. Therefore, the above range is preferable.

In addition, the amount of the metal powder, such as bismuth oxide, lead oxide, and iron-containing materials, is 10 to 60% by weight based on the total amount of the suspension. When the amount is less than 10% by weight, the electron reflecting ability of the anti-doping film is deteriorated. In the case of more than 60% by weight, the viscosity of the suspension becomes high, and when the liquid is sprayed onto the shadow mask, a hole clogging defect is likely to occur in the shadow mask.

The particle size of the metal powder, such as bismuth oxide, lead oxide, and iron-containing material, is in the range of 0.1 to 2.0 μm, so that no clogging of the shadow mask occurs, and metals can easily react during firing to form a dense film. desirable.

The obtained suspension is uniformly sprayed on the surface of the electron gun side of the shadow mask, and then fired in the firing furnace to obtain a blackened anti-doming film.

Hereinafter, specific embodiments of the present invention will be described in detail.

Example 1

Water glass containing bismuth oxide (Bi ₂ O ₃ ), 25% by weight powder, 5% by weight lead oxide (PbO) powder, 5% by weight iron powder, 28% solid component (K ₂ O.nSiO ₂ ) , 44% by weight of pure water and 1% by weight of lignin-based dispersant (manufactured by Ligno Tech Co., Ltd.) are mixed, and this is mixed and ground for 3 days in an alumina ball mill vessel to obtain a suspension.

This suspension is spray sprayed on the shadow mask to a thickness of 2 占 퐉, and then fired at a temperature of 450 ° C. in the kiln to obtain an excellent anti-adhesion coating with a shadow mask and a blackened anti-doming film.

Constituents of the obtained film were bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO) and iron oxide (Fe ₃ O ₄ ), together with their reaction compounds Bi ₁₂ PbO ₂₀ , Bi ₂ Fe ₄ O ₉ , and PbFe ₄ O ₇ was confirmed.

Example 2-3

The shadow mask of the present invention was prepared in the same manner as in Example 1, but having a blackened anti-doming film having a film thickness of 3 μm (Example 2) and 4 μm (Example 3) when spraying the suspension onto the shadow mask. .

Example 4

In the same manner as in Example 1, but instead of iron powder (Fe ₃ O ₄ ) to prepare a suspension using a powder, and employing it to prepare a shadow mask of the present invention.

Comparative Example 1

For comparison, the same method as in Example 1 was carried out, but the suspension component was 25% by weight of bismuth oxide powder, 20% by weight of water glass, 55% by weight of pure water, and the thickness of the anti-domming film was 2 μm. A mask was prepared.

Comparative Example 2-3

A conventional shadow mask was prepared in the same manner as in Comparative Example 1 except that the thickness of the film was 3 μm (Comparative Example 2) and 4 μm (Comparative Example 3).

1 is a schematic cross-sectional view of the present invention and the conventional cathode ray tube equipped with a shadow mask, a shadow mask (2) is provided on the inner surface of the panel (4) spaced at a predetermined interval, and the electron gun (1) side surface thereof The anti-domming film 3 is attached.

In Examples 1 and 4, it can be seen that the same anti-doping effect is obtained even when iron oxide powder is used in place of iron powder, because the iron powder is changed to iron oxide after the calcination process.

And the amount of thermal drift of the shadow mask prepared according to the method of the present invention and the shadow mask prepared according to the conventional method is shown in Table 1, which is the highest.

TABLE 1

2 is a graph showing the amount of heat drift according to the anti-domming film thickness of the conventional shadow mask (x-x) and the shadow mask (o-o) of the invention.

The amount of heat drift refers to the extent to which the hole of the shadow mask is pushed out by the thermal expansion of the shadow mask when the electron beam collides with the shadow mask. In Tables 1 and 2 it can be seen that the shadow mask of the present invention is much less heat drift than the conventional shadow mask. This is because the shadow radiation of the present invention is high thermal radiation rate is much less thermal expansion rate.

3 is a multi-channel photo detector (MCPD) spectrum indicating the degree of blackening of the anti-domming coating of a shadow mask prepared according to the conventional method (a) and the method (b) of the present invention. Compared. Here, it can be seen that the conventional shadow mask has a yellow green reflectance, and the shadow mask of the present invention has a black reflectance. As a result, it is understood that the shadow mask of the present invention is blackened.

As described above, the shadow mask manufactured according to the method of the present invention has a blackened anti-doming film and has a high anti-domming effect due to high reflectance and thermal radiation of incident electrons. You will get

Claims (7)

In a shadow mask embedded in a color cathode ray tube and having a color screening function and an anti-doping film on the electron gun surface, the anti-domming film is blackened, bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO), and iron oxide (Fe). ₃ O ₃ ) A shadow mask comprising a component and a reaction compound thereof. The shadow mask of claim 1, wherein the reaction compound comprises Bi ₁₂ PbO ₂₀ , Bi ₂ Fe ₄ O ₉ , PbFe ₄ O ₇ . In a method of manufacturing a shadow mask embedded in a cathode ray tube and having an anti-doping film on its electron gun surface, the anti-domming film is bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO), a material containing iron, pure water, water glass Spraying a suspension comprising a dispersant on the electron gun side of the shadow mask; Method of producing a shadow mask, characterized in that it is produced through the process of firing the obtained shadow mask at 400 to 500 ℃. The method of claim 3, wherein the amount of the bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO), the amount of the mixture containing iron is 10 to 60% by weight based on the total amount of the suspension, the preparation of the shadow mask Way. The method of claim 3, wherein the mixing amount of the lead oxide and iron-containing material is 1 to 30% by weight, based on the total amount of the suspension. The method of claim 3, wherein the iron-containing material is any one of an iron element or iron oxide (Fe ₃ O ₄ ). 4. The method of claim 3, wherein the particle size of the material including bismuth oxide, lead oxide and iron is 0.1 to 2.0 mu m.