KR100252946B1 - Method for making inner-shield in a color brain-tube - Google Patents

Abstract

PURPOSE: A method for manufacturing an inner shied for a color cathode ray tube is provided to have a permeability greater than 10,000 by annealing and throwing a thin plate higher than a recrystallization temperature. CONSTITUTION: An aluminum killed steel is continuously casted, hot-rolled, cooled rolled, decarbonizing annealed to obtain a thin plate. The thin plate is annealed higher than 700°C under a magnetic field of a reduction atmosphere and cooled to form a {111} texture more than 25% and grow a crystal particle greater than 40μm. The thin plate is formed to an inner shield and is processed by a blacken coating operation. The aluminum killed steel is annealed in an atmosphere in which an oxygen is absent. The aluminum killed steel is annealed in a vacuous atmosphere or using a hydrogen gas, a mixing gas of a hydrogen and a nitrogen, or a mixing gas of the hydrogen and an ammonia.

Description

Method for making inner shield for color cathode ray tube (Menerd for making inner-shield in a color brain-tube)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic shield for color cathode ray tubes (INNER SHIELD), and more particularly to a method of manufacturing a magnetic shield suitable for preventing color purity degradation of cathode ray tubes caused by an external magnetic field.

In the color cathode ray tube, as shown in FIG. 1, a panel 1 having a fluorescent film formed on its inner surface and a funnel 2 coated with conductive graphite on its inner surface are sealed with a fusion glass in a furnace at about 450 ° C. An electron gun 7 for generating an electron beam 9 is mounted on the neck 3 of the funnel, and a shadow mask 4, which is a color-selective electrode, is supported by the frame 5 inside the panel, and an electron beam on the outer circumferential surface of the funnel. It is equipped with a deflection yoke (8) for biasing the right and left.

The color CRT configured as described above receives hot electrons from the cathode of the electron gun when the image signal is input to the electron gun, and the emitted electrons are accelerated and focused toward the panel by the voltage applied from each electrode of the electron gun.

At this time, the electrons are adjusted by the magnetic field of the deflection yoke 8 mounted on the neck of the panel, and the adjusted electron beam is scanned by the deflection yoke 8 to the inner surface of the panel. Color selection is performed while passing through the slot of the shadow mask coupled to the side frame, and the selected electron beam collides with each fluorescent film on the inner surface of the panel to emit light to reproduce an image signal.

In order to prevent the electron beam from deflecting due to the influence of geomagnetism in the electron beam passing through the slot of the shadow mask to the fluorescent film, the geomagnetic shielding body behind the frame where the shadow mask is coupled (hereinafter, INNER SHIELD) 6) is attached.

The electron beam emitted from the electron gun is deflected under the influence of the geomagnetism, and a phenomenon in which the electron beam deviates from the original orbit is generated.

However, it is difficult to block the influence of the earth's magnetic field (hereinafter referred to as the "magnetic field") on the screen tube axis direction of the color cathode ray tube.

That is, the electron beam passing through the MASK lacks the correspondence to the horizontal magnetic field of the axial component, so that the image is deteriorated due to the deviation of the electron beam and hitting other colors.

In order to solve this problem, the inner shield is attached to the back of the frame combined with the shadow mask when viewed from the panel side. As the shield material, a thin metal plate having soft magnetic current is used. It is joined by.

At this time, since the inner shield 6 formed at a predetermined interval against the panel is made of a magnetic material, an external magnetic field flowing into the cathode ray tube is generated inside the cathode ray tube by flowing through the inner shield as shown in FIGS. 2A and 2B. Reduce the external magnetic field

The inner shield is hot-rolled, cold-rolled and decarbonized to obtain a thin plate by continuously casting aluminum-kilted steel (AK steel) having reduced carbon content with aluminum.

The color cathode ray tube manufacturer purchases the above-mentioned thin plate and manufactures the inner shield by drawing or forming.

Since the inner shield used is aluminum, aluminum-kilted steel (AK steel) which reduces carbon content of pure iron is pure iron, and the magnetic permeability for determining the intensity of magnetic flux flow into the inner shield among magnetic properties is within 3000 and the coercive force is 1.5 or less. We use thing of.

Since the degree of magnetic shielding is determined by the permeability, there is a limit to the characteristics of the inner shield shielding the external magnetic field.

As such, due to the limitations of the magnetic properties of the inner shield, the cathode ray tube is influenced by an external magnetic field, so that the external magnetic field flowing into the cathode ray tube is concentrated at the corner portion, and the magnetic field focused at the nose portion flows into the three-dimensional space. Because of the deflection, mis-resist is generated, and as a result, the cathode ray tube color purity is deteriorated.

The present invention has been made to solve the above-mentioned problems, by annealing the thin plate made of aluminum-kilted steel above the recrystallization temperature under a magnetic field to have a permeability characteristic of the initial permeability of 10,000 or more to reduce the amount of miss resist An object of the present invention is to provide an inner shield for color cathode ray tubes suitable for preventing color purity degradation.

1 is a cross-sectional view of a conventional color cathode ray tube structure

Figure 2a is a state diagram showing the external magnetic flow flowing into the cathode ray tube

FIG. 2B is an enlarged view of portion “A” in FIG. 2A

Figure 3a is a micrograph showing the grain size of the present invention

3b is a micrograph showing a conventional grain size

4 is a graph showing the amount of misresist

Explanation of symbols for main parts of the drawings

6: magnetic shield

The present invention for achieving the above object is hot-rolled, cold-rolled, decarbonized annealing the aluminum-kilted steel after continuous casting, annealing above the recrystallization temperature under magnetic field to form and cool more than 25% {111} texture After growing to a grain size of 40㎛ or more, it is formed into a magnetic shielding body and subjected to blackening coating to obtain a magnetic shielding body for color cathode ray tubes.

At this time, in forming into a magnetic shield, it can be performed by means such as drawing or forming.

According to the present invention, as a result of studying the aggregate structure of pure iron made of aluminum-kilted steel, the molten melt is continuously hot-rolled and cold-processed to a desired thickness after continuous casting. After decarburizing the content at 0.004% to 0.001%, annealing was performed under magnetic field at high temperature to improve the magnetic properties while forming {111} texture and increasing crystal growth. More than 25% of the {111} crystal faces are collected, resulting in a magnetic initial permeability of over 10,000.

Therefore, the present invention can improve the magnetic shielding performance of the inner shield by improving the magnetic properties even when the grains are 40 µm or more. It has been found that by reducing the influence of the geomagnetism, the amount of misresistance can be reduced to prevent a decrease in color purity.

When described in more detail with respect to the present invention.

First, in the case of manufacturing aluminum-kilted steel, the melt is continuously cast and then hot rolled and cold worked to a desired thickness, followed by decarburization annealing under hydrogen atmosphere to decarburize the carbon content to 0.004% to 0.001%, and then form {111} texture. The high temperature annealing treatment is carried out at a temperature of 700 ° C. or higher in order to cause crystal growth.

If the temperature is less than 700 ℃, {111} texture is difficult to form and the crystal growth rate is slowed to improve the magnetic properties is difficult to expect.

The air atmosphere at this time is performed at a temperature of a hydrogen atmosphere in which oxygen does not act.

If oxygen enters during annealing, oxidation occurs at a high temperature, causing the soft magnetic surface to be oxidized, and the desired magnetic properties cannot be obtained.

In an annealing treatment, hydrogen gas or a mixed gas of hydrogen and nitrogen or a mixed gas of hydrogen and ammonia is used in a hydrogen atmosphere to make the atmosphere free of oxygen.

In the annealing, the magnetic field is applied under the magnetic field. The magnetic field is generated by using the principle of solenoid so that the magnetic field can flow in the feed direction in the continuous annealing furnace. A permanent permanent magnet is installed facing the pole, annealed in the magnetic field and cooled in the magnetic field.

In this case, the magnetic properties are improved while the magnetic arrangement is uniformly arranged in the tissue of aluminum-kilted steel by the external magnetic field.

At this time, the magnetic field is applied to more than 100 gauss.

When the annealing is performed at a temperature above the above-mentioned temperature, not only recrystallization having the {111} texture is easily generated, but also after the recrystallization occurs, grains grow continuously and change of magnetic properties occurs.

As the annealing temperature increases, grains grow faster, the magnetic permeability is greatly improved, and the coercivity becomes smaller, and the magnetic shielding characteristics of the inner shield are greatly improved.The lower the annealing temperature, the longer the heat treatment time occurs, so that recrystallization occurs and the grains grow. Magnetic properties are improved.

However, even in the above conditions, it must be taken into consideration that the magnetic properties change depending on the size of the grains, so the time must be adjusted at the annealing temperature.

The annealing time is determined in consideration of the formation degree of the {111} texture and the degree of crystal growth. In the case of thin plates, the annealing heat treatment can be performed at the high temperature for at least 1 minute.

And if the grain size is not more than 40㎛, it is difficult to expect the improvement of the magnetic properties. Impurities such as carbon, nitrogen, sulfur, or aluminum in the grains move to the boundary of the grains, and since one crystal grain has a single magnetic domain behavior, the unit area is small as shown in FIG. 3b. As the number of grains increases in the interior, as a result, the transfer of magnetic spins from one grain to an adjacent grain, that is, the movement of the magnetic field, is slowed by the impurity of the grain boundary and the grain boundary. The permeability is reduced.

However, when the grain size is 40 µm or more, as shown in FIG. 3A, the number of grains per unit area decreases, thereby making it easy to transfer magnetic components in the crystal, thereby reducing coercive force and increasing permeability, thereby increasing magnetic shielding performance.

The purpose of forming the {111} texture is that in the case of pure iron, which is a soft magnetic aluminum-kilted steel, it is easy to flow in a direction parallel to the thin plate surface because the hard plane of magnetization, that is, the {111} plane, is difficult to flow magnetic fields. .

When the {111} texture is less than 25%, it is difficult to achieve the above effect. Thus, the formation of the {111} texture is more than 25% and the average grain size is increased to 40 µm or more, thereby improving the performance of the magnetic shielding.

As a result, it is possible to reduce color resist by reducing misresistance caused by external magnetic field.

The following is described according to the embodiment.

Forging soft iron, a soft magnetic aluminum guild steel, cold-rolled to produce a thin plate after hot rolling, annealing under magnetic fields facing the same stimulus, and annealing under the conditions shown in Table 1 below. After forming the aggregates and growing the crystals, to analyze the degree of aggregation of the {111} plane on the crystal plane, the pole figure was analyzed using the X-RAY diffractometer, and then the unit volume per unit volume using the ODF analyzer. The volume fraction of the crystal plane was measured to evaluate the degree of aggregation of the {111} crystal plane.

And the results of the analysis of magnetic properties and grain size are shown in Table 2.

A color cathode ray tube was fabricated using a pure iron sheet made of aluminum-kilted steel under the same conditions as those of Table 1, and the amount of misresistance was evaluated while changing the strength of the geomagnetic field.

It can be seen from Table 2 that as the volume fraction of the {111} crystal surface increases as the heat treatment at high temperature increases the size of the crystal grains, the magnetic properties are improved, and the magnetic properties are further improved when heat-treated in the magnetic field.

As in Example 1 and Example 2 of Table 1 and Table 2, in the case of a cathode ray tube manufactured with a shield manufactured after annealing and cooling under a magnetic field at a temperature of 700 ° C. or higher, the miss resist characteristics were compared to those of the comparative example (conventional: decarburization). After annealing, it can be seen that it is better than the self shielding molding).

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Annealing Condition Hydrogen atmosphere 750 ℃, heat treatment for 20 minutes 5000 GAUSS magnetic field applied Hydrogen 70%, Ammonia 30% Atmosphere 780 ℃, 10 Fission treatment with 1000 Gauss magnetic field Hydrogen 30%, Nitrogen 70% Atmosphere 850 ℃, 5 minutes Not implemented.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 {111} face 95% 90% 40% 15% Grain size 120 μm 95 ㎛ 90 μm 35 μm Initial permeability 13,450 136,800 6400 1300 Coercive force 0.40 Oe 1.34 Oe 0.8 Oe 2.40 Oe

As described above, when the aluminum-kilted steel having a body-centered cubic structure is annealed under a magnetic field after cold working and cooled under a magnetic field to produce a magnetic shielding body, an average grain size of 40% or more of {111} crystal surfaces is gathered on a thin plate surface. It becomes more than micrometer.

Therefore, the magnetic properties of the magnetic shield are further improved than when not annealed in the magnetic field, and the magnetic shielding performance is further improved, and thus, the amount of miss resist caused by the external magnetic field can be reduced to prevent color purity degradation.

Claims (6)

After continuous casting of aluminum-kilted steel, the hot-rolled, cold-rolled, and decarbonized annealed thin plate was annealed and cooled at a temperature of 700 ℃ or higher under a magnetic field of reducing atmosphere to form more than 25% {111} texture and crystal grain 40㎛ A method of manufacturing an inner shield for color cathode ray tubes (INNER SHIELD), characterized in that the above-mentioned growth is carried out to be molded into a magnetic shielding shape and blackened. The method of claim 1, A process for producing a magnetic shield for color cathode ray tubes (INNER SHIELD), characterized by annealing in an oxygen-free atmosphere. The method of claim 2, A process for producing an INNER SHIELD for a color cathode ray tube, characterized in that an oxygen-free atmosphere is subjected to a vacuum atmosphere or annealed using hydrogen gas or a mixed gas of hydrogen and nitrogen or a mixed gas of hydrogen and ammonia. The method of claim 1, A method of manufacturing an INNER SHIELD for a color cathode ray tube, characterized in that the forming of the magnetic shield is a drawing or forming means. The method of claim 1, A magnetic shielding body has a body-centered pressure-sensitive structure, {111} crystal surface is a method for producing a magnetic shield body for color cathode ray tube (INNER SHIELD) characterized in that the aggregate. The method of claim 5, An initial permeability of a magnetic shielding body is 10000 or more, The manufacturing method of the magnetic shielding body for color cathode ray tubes (INNER SHIELD) characterized by the above-mentioned.

Images