KR0130199B1 - Mask tube for display, notably for color television background of the invention - Google Patents

Abstract

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Description

Mask tube for display or color television

1 is a diagram illustrating the surface of a color television tube mask coated with bismuth by a standard technique with an electron microscope.

2 is a surface view of a mask coated with a mixture of potassium silicate and bismuth.

* Explanation of symbols for main parts in the drawings

10: blank zone

BACKGROUND OF THE INVENTION The present invention relates to mask tubes for displays, in particular color televisions.

Description of the Prior Art A mask type color television tube is formed from a glass bulb at the end of a screen on which a luminophor is deposited. When the light emitters hit light by radiation, the light emitter generally generates red, green, or blue light emission. The light emitters are arranged on the screen in three triads. Three pairs include green emitters, red emitters and blue emitters. Each light emitter is excited by a corresponding electron beam. In front of the mask tube are a pair of three masks each having holes of size and arrangement such that the emitters of the determined color are excited only by the electron beam assigned to the color. Most of the electrons of the three beams are stopped by a mask. The collision of electrons heats the mask, thereby causing a deformation that may raise the temperature and damage the color of the image of the screen. In order to reduce the heating of the mask, it has already been proposed to coat the surface of the steel mask facing the electron layer (opposite the screen) with a heavy metal or heavy metal compound of atomic number 70 or above. The heavy metal, for example bismuth, has a reflective effect on the electrons, which reduces absorption and thus reduces heating. Coatings of heavy metals or heavy metal compounds on masks have defects in uniformity, which impair the reflecting capacity of the coating. The present invention overcomes the above drawbacks.

[Overview of invention]

According to the invention, the heavy metal or heavy metal compound is mixed with alkaline silicate, wherein the ratio between the specific gravity of the heavy metal and the specific gravity of the silicate is between 7 and 17, preferably 12 to each other. Alkaline silicates are selected from, for example, potassium silicate, lithium silicate, sodium silicate. E.g,

The addition of alkali silicate, which is potassium silicate, can be suitably attached to the metal mask as well as the appropriate uniformity of the mixture of the silicate and the heavy metal or heavy metal compound. The amount of heavy metal deposited per region is greater than by known techniques. The proportion of silicates chosen is small enough not to significantly interfere with the heat reduction effect given by the heavy metals. In addition, the ratio between the specific gravity of the heavy metal or heavy metal compound and the specific gravity of the silicate provides optimal adhesion to the metal mask and can be coated with sputtering or spray equipment. If the proportion of heavy metals or heavy metal compounds is less than or equal to the limit 7 previously indicated, no adequate adhesion of the coating to the mask is obtained. Furthermore, even if the heavy metal compound is bismuth oxide and the alkaline silicate is potassium silicate, the bismuth silicate is not formed at a ratio of 12 because of the lack of silica to bismuth. Alkaline silicates are stable at high temperatures, ie at temperatures above 400 ^° C., thus resisting the heat treatment experienced by the mask during the tube manufacture. In order to obtain better results, the mixture of heavy metals or heavy metal compounds and alkaline silicates is preferably formed of particles having a size on the order of 0.5 to 0.8 μm. After the alkaline silicate and the mixture of heavy metals or heavy metal components are used, a significant decrease in the temperature of the iron-based mask is observed. This entails a reduction of 35% to 45% of the mask deformation at the start of the operation of the tube. FIG. 1 is a view of the surface of a color television tube mask coated with bismuth by standard techniques with an electron microscope, and FIG. 2 is similar to FIG. Is a surface view of a mask coated with a mixture of and bismuth. In both figures, the cleaner the mask, the greater the density of bismuth. Generally, the blank zone 10 of FIG. 2 has a larger area than the blank zone 10 of FIG. Thus, the density of bismuth at the surface is much greater for the present invention. Therefore, it can be seen that the present invention facilitates an increase in the density of bismuth in terms of quantity.

Claims (4)

The face of the iron-based mask against the (correction) screen is a display or color television mask tube coated with a heavy metal or heavy metal compound having an atomic number of 70 or more, wherein the heavy metal or heavy metal compound is mixed with an alkaline silicate, Or the ratio between the heavy metal compound and the silicate is between 7 and 17, preferably 12 to each other. (Correction) The mask tube for display or color television according to claim 1, wherein the mixture of the alkaline silicate and the heavy metal or heavy metal compound comprises particles having a size of about 0.5 to 0.8 m. (Correction) The mask tube for display or color television according to claim 1 or 2, wherein the heavy metal is bismuth. (Correction) The mask tube for display or color television according to claim 2, wherein the alkaline silicate is selected from at least one potassium silicate, lithium silicate, and sodium silicate.

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