JPS6217937A - Color selection electrode for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent degradation of picture quality by limiting the grain size of dispersed powder in surface treating layer. CONSTITUTION:With respect to hole-shaped distorsion of color selection electrode 13, abnormal coarsensess of about 5mum can be distinguished by human eye and since the material formed on the surface of said electrode 13 will function as a part of color selection electrode hole 16, the grain size of Bi2O3 forming a projection 2a is made smaller than 5mum. Consequently, even when powder will form a projections on the inner wall face of color selection electrode hole, the shape of picture element on the screen will never change for human eyes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a color selection electrode built into a color cathode ray tube, and particularly to its surface treatment.

[Prior art] The manufacturing process of the shadow mask, which is a component of a color cathode ray tube, that is, the color selection electrode, is described in Denshi Kagaku (published by Sanpo Co., Ltd.), 1964, VOL 14 (No. 9), No. 3.
6, 39 and 40. As shown in FIG. 3, the color selection electrode (13) consists of a panel (lO) which is a dish-shaped glass container, and a funnel-shaped funnel (12) containing an electron gun (11) that emits an electron beam.
), and is supported by the support part (!4) and built into the panel (1o).

This color selection electrode (13) is a shadow mask.

Thin iron plates with a thickness of 0.15 to 0.30 mm, or in recent years,
It is manufactured using a low expansion material of 36% Ni-Fe, and has a round or rectangular electron beam passage hole with a diameter of approximately 0.15 mm drilled in a dome shape by etching. In order to obtain a curved surface close to a spherical shape on the inner surface of the panel, it is heat-treated at 600 to 900°C in a hydrogen stream, press-molded into a predetermined shape, and then the surface is surface treatment to obtain black rust. The process of obtaining this black rust is called surface blackening.

The above surface treatment can be done by first completely removing the oil that adhered during pressing, then dipping it in alkaline molten salt and heating it to obtain black rust, or by using water vapor or carbon dioxide gas to blacken the surface. The resulting black rust film is exposed to about 400 to
The heat treatment at 450° C. serves to prevent the iron, which is the base material of the color selection electrode (13), from oxidizing and forming red rust (Fe203).

In addition, during operation as a color cathode ray tube, approximately 80% of the electron beam emitted from the electron gun is absorbed by this color selection electrode (1
3) It collides with the shadow mask. Therefore, the kinetic energy of the electron beam is converted into thermal energy, and the shadow mask rises by about 40 to 80 degrees Celsius, causing thermal expansion, and as a result, distortion occurs in the shadow mask. By treating it with black rust, the radiation rate can be reduced to 0.15-0.
It has been increased from 38 to 0.75, which also serves to improve heat dissipation and reduce distortion caused by heat.

In recent years, color cathode ray tubes are often used to stare at a screen, and color cathode ray tubes with a flat shape have come to be used. In this type of color cathode ray tube, thermal distortion of the color selection electrode (13) causes
Screen-L shows the phenomenon of color shift, so as a countermeasure,
Materials mainly composed of PbO or Bi2O3 are used and have great effects because they have excellent properties such as thermal radiation, elastic scattering of electron beams, and thermal expansion coefficients.

[Problems to be Solved by the Invention] However, the end portion of the surface treatment layer in which the material L is dispersed may protrude onto the inner wall surface of the color selection electrode hole, and the protrusion portion of the surface treatment layer may interfere with the image screen. This appears as it is in the shape of the picture element, resulting in an image composition different from that of a uniformly formed part, resulting in uneven image quality.

This invention was made to solve these problems, and by regulating the particle size of the material 4 applied to the surface of the color selection electrode, the color of the color cathode ray tube was improved to prevent uneven image quality. The purpose is to provide a sorting electrode.

[Means for Solving the Problems] In the color selection electrode of the color cathode ray tube according to the present invention, the particle size of the powder dispersed in the surface treatment layer is set to 5 micrometers or less.

[Function] The unevenness of approximately 5 micrometers in the color selection electrode hole is the limit of the size that can normally be discerned by the human eye, and by setting the particle size of the powder to 5 micrometers or less,
Even if the powder forms a protrusion on the inner wall surface of the color selection electrode hole, the shape of the picture element on the video screen does not change to the human eye.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged sectional view showing a part of the color selection electrode (13). In FIG. 0, the color selection electrode (13) is in a state where black rust has been formed by heat treatment, as in the conventional case. On the surface of this black rust, Bi203 (2
) The surface treatment layer (1) is formed by spraying a liquid mixture (4) (see Figure 2) in which powder is mixed into water glass (3).

There are two types of water glass (3): sodium-based and potassium-based. In the examples, potassium-based water glass is used.

Figure 2 shows the above prepared liquid (4) on the surface of the color selection electrode (13).
In this explanatory diagram showing a state in which -h is sprayed, the liquid preparation (4) is sprayed by a spray gun (5) using air and applied to the surface of the color selection electrode (13). (θ) is a l\ring for suspending the color selection electrode (13).

By spraying the liquid mixture (0) onto the L color selection electrode (13), as shown in FIG. (17
) may remain in contact with. Most of the particles fall off due to the impact between the particles caused by the wind pressure during spraying and do not remain, but even if they do remain, it is necessary to select a coating material that will not cause a decrease in the image quality of the color cathode ray tube. ,
For this purpose, even if it adheres to the tip of the color selection electrode hole (1B), that is, the constriction (17), it may not be distinguishable.

By the way, regarding the distortion of the hole shape in the color selection electrode (13), the irregularity is about 5 micrometers compared to the normal part, which is the limit of the size that can be normally discerned by the human eye. Since the substance S formed on the surface of the color selection electrode (13) also acts as a part of the color selection electrode hole (16), the powder forming the convex portion (2a) in -I-, that is, Bi203 (2) It is necessary to reduce the particle size to 5 micrometers or less.

1-The fat powder (2) has a melting point equal to or higher than the heat treatment temperature during the color cathode ray tube manufacturing process;
It can also be applied to powder whose shape is deformed by the heat treatment at a temperature lower than the heat recording temperature.

Note that the surface of the color selection electrode (13) is designed to prevent temperature rise due to thermal conversion of kinetic energy caused by electron beam impact.
From the viewpoint of viewing, it is better to roughen the surface to increase the surface area. In addition, from the perspective of expecting a radiation effect, the surface should be more uneven, and the powder to be applied (2
) does not need to be as fine as possible, but as large as possible, so it is necessary to select a particle size that does not reduce image quality and provides a radiation effect.

[Effects of the Invention] As explained above, according to the present invention, by controlling the particle size of the powder dispersed in the surface treatment layer of the color selection electrode, deterioration in the image quality of the color cathode ray tube can be avoided. can do.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view showing an embodiment of the present invention, FIG. 2 is an explanatory view showing a state in which a liquid mixture is applied, and FIG. 3 is an exploded perspective view showing a color cathode ray tube. (1)...Surface treatment layer, (2)...Powder (Bi20
3), (13)...color selection electrode. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A color selection electrode for a color cathode ray tube having a surface treatment layer in which powder is dispersed, characterized in that the particle size of the powder is 5 micrometers or less. (2) The color selection electrode for a color cathode ray tube according to claim 1, wherein the powder has a melting point higher than the heat treatment temperature in the color cathode ray tube manufacturing process.