JPH0917349A - Color picture tube and its manufacture - Google Patents

Abstract

PURPOSE: To form an electron reflecting film having strong bond strength on an electron gun side surface of a shadow mask without increasing the process number. CONSTITUTION: An electron reflecting film 24 is formed on an electron gun side surface of a shadow mask 20 using a cold-rolled steel plate as a base material, and a surface except this electron reflecting film forming part is covered with an oxide film. The electron reflecting film is composed of a tungsten oxide particle and a primary aluminium phosphate as a binding agent, and is formed by being baked in a heating process at oxide film forming time after an electron reflecting film forming liquid is applied to the shadow mask before the oxide film is formed. According to such a manufacturing method, bond strength can be improved without increasing a heating process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube and a manufacturing method thereof, and more particularly to a color picture tube having an electron reflection film for suppressing thermal expansion of a shadow mask and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, a color picture tube has an envelope composed of a panel 1 and a funnel 2, as shown in FIG.
A phosphor screen 3 composed of a three-color phosphor layer that emits green and red is provided, and a shadow mask 4 is arranged inside the phosphor screen 3 at a predetermined distance (q value) away from the phosphor screen 3. On the other hand, 3 in the neck 5 of the funnel 2
An electron gun 7 that emits electron beams 6B, 6G, and 6R is arranged. Then, the three electron beams 6B, 6G, 6R emitted from the electron gun 7 are deflected by the magnetic field generated by the deflecting device 8 mounted outside the funnel 2, and the phosphor screen 3 is horizontally moved through the shadow mask 4. By vertical scanning, a structure for displaying a color image is formed.

The shadow mask 4 is for selecting the three electron beams 6B, 6G, 6R emitted from the electron gun 7 and correctly landing them on a predetermined three-color phosphor layer, as shown in FIG. In addition, the main body 10 having a convex curved surface on the phosphor screen side is provided with a mask main body 11 having a large number of openings formed in a predetermined array, and a mask frame 12 attached to the peripheral portion of the mask main body 11. The mask body 11 has a circular opening and a rectangular opening, and the shadow mask 4 having a circular opening is mainly used for a color picture tube for a display for displaying characters and figures. The shadow mask 4 having a rectangular opening is
It is used in consumer color picture tubes used in general households.

In the color picture tube, the electron beam that reaches the phosphor screen through the opening of the mask body 11 is one of all electron beams emitted from the electron gun.
It is about 5 to 20%, and most of the other electron beams collide with the shadow mask 4 and cause the mask body 11 to move to 8%.
Heat to about 0 ° C. In this case, in the conventional shadow mask 4, the mask body 11 generally has a thermal expansion coefficient of 12 ×
Since it is formed of a cold-rolled steel plate having a thickness of 10 ⁻⁶ / ° C. (10 to 20 ° C.) and a thickness of 0.1 to 0.3 mm, the mask body 11 is thermally expanded by the above heating, and the mask main body 11 is expanded in the phosphor screen direction. Causes so-called doming, which bulges. As a result, the distance between the phosphor screen and the shadow mask 4 deviates from the predetermined q value, and the three electron beams do not land correctly on the predetermined phosphor layers, resulting in deterioration of color purity.

The landing shift of the electron beam due to the thermal expansion of the mask body 11 is an FS (Flat Squre) in which the effective portion of the panel is flattened from the ergonomic point of view to reduce the reflection of external light and the distortion of the image. In the case of pipes, it becomes particularly large. That is, in the FS tube, the main surface portion of the mask main body is also flattened corresponding to the flattening of the effective portion of the panel, and the curvature radius of the mask main body is larger than that of the shadow mask of a normal color picture tube. Therefore, even if the thermal expansion of the mask body of an ordinary color picture tube is performed to the same extent, the landing deviation of the electron beam with respect to the phosphor layer becomes large and the deterioration of the color purity becomes remarkable.

As a means for preventing the deterioration of the color purity due to the thermal expansion of the mask body, Japanese Patent Publication No. 42-25446 discloses an iron-nickel alloy having a thermal expansion coefficient of about 1/10 that of a cold-rolled steel sheet. It is shown that the mask body is formed by using a low thermal expansion material such as amber.
When the mask body is formed of the low thermal expansion material as described above, the doming can be reduced, the landing shift of the electron beam with respect to the phosphor layer can be reduced, and the deterioration of the color purity can be reduced. However, a low thermal expansion material such as amber is expensive and has a high yield point strength after annealing, so that the mask body is difficult to be molded into a predetermined shape, and the molding yield is low. Therefore, the price is higher than that of a color picture tube whose mask body is made of a cold rolled steel plate.

As another means for preventing the deterioration of the color purity due to the thermal expansion of the mask body, a film is formed on the mask body, and the effect of this film suppresses the doming to reduce the deterioration of the color purity as follows ( There are methods shown in (a) to (d).

(B) Lead borate crystallized glass is coated on the surface of the mask body by the method disclosed in Japanese Patent Laid-Open No. 60-54139, and the coating is melt-bonded by heat treatment at high temperature. Then, there is a method of providing a doming suppression effect. However, such a method is not preferable because it contains harmful lead in the coating film and thus requires careful handling from the viewpoint of working environment and pollution.

(B) According to the method disclosed in Japanese Examined Patent Publication No. 60-14459, a liquid containing particles of a heavy metal substance having an atomic number exceeding 70, for example, bismuth oxide particles, is formed on the surface of the mask body on the electron gun side. There is a method of forming an electron reflection film by applying a water-soluble suspension containing it by a spray method. However, this method is not sufficient in preventing the heating of the mask body by reflecting the electron beam, and is not sufficient in suppressing the doming caused by heating of the mask body. The desired effect cannot be obtained.

(C) According to the method disclosed in Japanese Patent Laid-Open No. 4-48530, a water glass solution in which bismuth oxide particles, tungsten particles and partially graphitized carbon particles are mixed is applied to the surface of the mask body on the electron gun side. By applying by spraying method, in addition to reflection of electron beam, enhance heat conduction and heat radiation,
This is a method of suppressing the doming of the mask body. According to this method, deterioration of color purity can be prevented relatively well. However, in this method, the material particles in the coating solution must be pulverized by a ball mill or the like until the average particle diameter becomes about 2 μm, and the uniform pulverization is difficult and a sharp particle size distribution cannot be obtained. for that reason,
When the above liquid is applied, changes in the shape of the openings in the mask body and clogging of the openings are likely to occur. In order to prevent this, it is necessary to control the thickness of the coating to about 3 μm, but it is difficult to spray in a state where the particle size distribution is not sharp and particles with different specific gravities are uniformly mixed. , It is difficult to obtain a uniform film.

(D) According to the method disclosed in Japanese Patent Laid-Open No. 62-11024, a conductive coating film containing a metal having a small atomic number is formed on the surface of the mask main body using an amorphous metal oxide or the like as a binder. Formed, with the improvement of heat radiation,
There is a method of preventing the change of the orbit of the electron beam due to charging, thereby preventing the deterioration of the color purity.

[0012]

As described above, as a means for preventing the deterioration of the color purity of the color picture tube due to the thermal expansion of the shadow mask, electron reflection, heat conduction, heat radiation, etc. on the surface of the mask body have hitherto been performed. Methods are known for forming coatings that enhance the conductivity. However, in such a method, as compared with the case where a coating is not formed, the step of applying a liquid for forming a coating to the mask body to form a predetermined coating, and the high temperature heat treatment step of firing the coating are performed. It is necessary and has a large facility and financial burden.

In particular, when a film is formed on the surface of the mask body on the side of the electron gun, there is a high possibility that gas will be released by the impact of the electron beam emitted from the electron gun, and the emitted gas will poison the cathode of the electron gun. However, the electron emission characteristics are deteriorated, the life of the color picture tube is shortened, and the withstand voltage characteristics are deteriorated. In order to reduce the amount of the released gas, the film may be fired at a high temperature, but the mask body formed into a predetermined shape is deformed when heat-treated at a high temperature of 650 ° C. or higher. Is not possible, and the gas cannot be sufficiently released from the coating.

The present invention has been made in view of the above problems, and an electron reflection film that does not deteriorate the electron emission characteristics of the cathode is formed on the electron gun side surface of the mask body without increasing the number of steps. It is an object of the present invention to provide a color picture tube and a method for manufacturing the same that alleviate thermal expansion of the mask main body due to the collision of electron beams by this electron reflection film and do not cause deterioration of color purity.

[0015]

An electron reflection film is formed on a surface of a shadow mask having a cold-rolled steel sheet as a base material on the electron gun side, and a surface other than the electron reflection film formation portion is covered with an oxide film. In the color picture tube, the electron reflection film was directly formed without forming the oxide film on the electron reflection film formation portion.

Further, the electron reflection film is a film in which metal oxide particles are bound by the primary aluminum phosphate.

Further, an electron reflection film is formed on the surface of the shadow mask formed from a cold-rolled steel sheet as a base material in a predetermined shape on the electron gun side, and the surface other than the electron reflection film forming portion is covered with an oxide film. In the method for producing a color picture tube, the electron reflection film forming liquid is applied to the shadow mask, which has been molded into a predetermined shape and washed before the formation of the oxide film, to form the electron reflection film forming film.

Further, the electron reflection film forming coating formed by applying the electron reflection film forming liquid is baked at the time of forming the oxide film to form an electron reflection film.

[0019]

As described above, when the electron reflection film is directly formed on the electron reflection film formation portion of the shadow mask without forming an oxide film, for example, an electron reflection film forming liquid containing primary aluminum phosphate as a binder is used. When forming an electron-reflecting film using the above, the pH of the electron-reflecting film forming liquid is 1
Therefore, the phosphate ion reacts with iron on the surface of the base material made of the cold-rolled steel sheet to form a compound, and an electron-reflecting film having high adhesiveness can be formed.

Further, when the electron reflection film forming liquid is applied to the shadow mask before forming the oxide film, which has been molded into a predetermined shape and washed, to form an electron reflection film forming film, uneven coating of the electron reflection film forming liquid is eliminated, A uniform electron reflection film can be formed.

Further, if the electron reflection film forming film is baked at the time of forming the oxide film to form the electron reflection film, it is not necessary to provide a special baking furnace for baking, and the oxide film is formed at the high temperature necessary for forming the electron reflection film. At the same time, the electron reflection film can be formed. Further, it is possible to obtain a color picture tube which does not deteriorate the emission characteristics and the withstand voltage characteristics by sufficiently releasing the occluded gas from the base material, the electron reflection film forming coating, etc. by the high temperature heat treatment.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 2 shows a color picture tube which is one of the embodiments. This color picture tube has an envelope composed of a panel 1 and a funnel 2, and a phosphor screen composed of a three-color phosphor layer that emits blue, green, and red on the inner surface of the effective portion of the panel 1 having a curved surface. 3 is provided, and a shadow mask 20 described below is arranged inside the phosphor screen 3 at a predetermined distance (q value) away from the phosphor screen 3. On the other hand, 3 electron beams 6B, 6G, 6R are placed in the neck 5 of the funnel 2.
Is provided. Then, the three electron beams 6B, 6G, 6R emitted from the electron gun 7 are deflected by the magnetic field generated by the deflecting device 8 mounted outside the funnel 3, and the phosphor screen 3 is leveled through the shadow mask 20. By vertical scanning, a structure for displaying a color image is formed.

As shown in FIG. 1, the shadow mask 20 has a plate thickness of 0.1 to 0.0.1 in which a large number of openings are formed in a predetermined array in a main surface portion 21 having a convex curved surface on the phosphor screen side.
A mask body 22 made of a cold rolled steel plate of about 3 mm, and a mask body 2 attached to the peripheral portion of the mask body 22.
2 and a mask frame 23 made of a cold-rolled steel plate having a thickness larger than 2. Particularly, in the shadow mask 20 of this example, an electron reflection film 24 is formed on the surface of the mask body 22 on the electron gun side, and the surface other than the electron reflection film formation portion is covered with an iron oxide film (not shown). It has been broken. The electron reflection film 24 is composed of spherical tungsten oxide particles containing tungsten trioxide as a main component and having a particle size of 1 μm or less and primary aluminum phosphate binding the tungsten oxide particles, and is formed to have a film thickness of 2 to 15 μm. ing.

As shown in FIG. 1, the shadow mask 20 includes a plurality of stud pins 25 provided on the panel 1 and a plurality of stud pins 25 attached to the mask frame 23 and engaged with the stud pins 25. It is supported inside the panel 1 by the elastic support member 26 of FIG.

To manufacture such a color picture tube, as shown in FIG. 3, first, a mask frame is welded to a mask body manufactured by a method described later to assemble a shadow mask, and the mask frame of this shadow mask is The elastic support is welded so that the distance from the inner surface of the effective part of the panel is a predetermined distance, and the elastic support is detachably locked to the stud pin provided on the panel to form the panel / mask combination. Assemble. Next, with respect to this panel / mask combination, a phosphor screen is formed on the inner surface of the effective portion of the panel by a photo printing method using a shadow mask as an exposure mask. On the other hand, a conductive paint containing graphite as a main component is applied to the inner surface of the funnel to form an inner conductive film. Next, the panel on which the phosphor screen is formed and the shadow mask is mounted and the funnel on which the inner conductive film is formed are combined and placed in a heating furnace, and they are integrally bonded (sealed) by frit glass. The electron gun is then sealed within the neck of the envelope which consists of the panel and funnel joined together. Then, the sealed envelope of the electron gun is exhausted. After that, in order to increase the degree of vacuum inside the envelope, the getter placed inside the envelope is heated and scattered, and further aging is performed to stabilize the electron emission from the cathode of the electron gun, and to increase the withstand voltage. It is manufactured by performing characteristic inspection after applying withstand voltage treatment.

As shown in FIG. 4, the mask main body is manufactured by first forming a large number of circular or rectangular openings in a cold-rolled steel sheet in a predetermined arrangement by a photoetching method, and then forming a flat flat mask. To form. Next, this flat mask is annealed, and the annealed flat mask is pressed into a predetermined shape. Next, the molding mask is washed to remove surface stains such as press oil attached during molding.

Then, the electron reflection film forming liquid described below is applied to the surface of the cleaned mask body on the electron gun side by an air spray or airless spray method to form an electron reflection film forming film. The electron reflection film forming liquid is
Aluminum phosphate _{(AlO 3 · 3P 2 O 5} · 6H
₂ O) as a binder, and a liquid containing at least 15 to 50% by weight of spherical tungsten oxide fine particles containing tungsten trioxide (WO ₃ ) as a main component and having a particle size of 1 μm or less. Next, the mask main body on which the electron reflection film-forming coating is formed is placed in a blackening furnace and treated at 550 to 650 ° C. to simultaneously form an iron oxide film on the surface other than the electron reflection film-forming coating formation portion. Then, the electron-reflecting film forming coating is fired to form an electron-reflecting film having a thickness of 2 to 15 μm to obtain a mask body. The mask body is then inspected for surface condition.

The manufacturing method of the mask main body is different from the conventional manufacturing method. (A) After forming the mask, applying an electron reflection film forming liquid to form an electron reflection film forming film before forming an oxide film. (B) Forming an electron-reflecting film at the same time as forming the oxide film (c) Using an electron-reflecting film forming liquid having a specific composition.

That is, in the conventional method for manufacturing a mask body, as shown in FIG. 5, a flat plate-shaped flat mask is formed by a photo-etching method, and then annealing treatment → press molding → cleaning → blackening treatment → inspection are sequentially performed. After that, the electron reflection film forming liquid application → baking → inspection is performed to manufacture the mask main body, but the mask main body of this example is formed by applying the electron reflection film forming liquid before forming the oxide film as described above. An electron-reflecting film-forming film is formed and baked at the same time when the oxide film is formed to form an electron-reflecting film.

By forming the electron reflection film as described above, the following effects can be obtained. (B) It becomes possible to perform baking at a high temperature, and the adhesion of the electron reflection film can be increased. That is, heat treatment at 520 ° C. or higher is necessary in order to give sufficient adhesion and water resistance to the electron reflection film using the primary aluminum phosphate as a binder, but it is generally the highest in the manufacturing process of color picture tubes. The heat treatment temperature has a limit of about 460 ° C., which is lower than the glass transition point, in order to prevent deformation of the glass panel, and cannot be heated to a temperature of 520 ° C. or higher. However, when the oxide film is processed, it can be processed at 550 to 650 ° C., and the high-temperature heat treatment can enhance the adhesion of the electron reflection film. (B) By the high temperature heat treatment at the time of forming the oxide film, it is possible to sufficiently release the water of crystallization and the occluded gas of the material forming the cold-rolled steel sheet and the electron reflective film forming coating. As a result, the color cathode ray tube is incorporated into the color cathode ray tube, the gas emission is small even if the electron beam collides during operation, the deterioration of the cathode constituting the electron gun can be reduced, and the color cathode ray tube having a long life and good withstand voltage characteristics can be obtained. . (C) Since the electron reflection film forming film is baked at the same time when the oxide film is formed, the manufacturing process of the mask body can be shortened and the electron reflection film can be formed without installing a special baking furnace. (D) 15 to 5 spherical tungsten oxide fine particles having a particle size of 1 μm or less using the first aluminum phosphate as a binder.
Since the electron-reflecting film forming liquid containing 0% by weight of a specific composition is applied before the oxide film is formed to directly form the electron-reflecting film, the electron-reflecting film having strong adhesive force and free from film peeling can be obtained.

That is, a strong inorganic continuous film is generally easily peeled off, but when an electron reflection film is formed using the electron reflection film forming film forming liquid having the above-mentioned specific composition, a film having a dense structure is formed in a small amount. It can be a film in which individual particles are connected like a network structure. Moreover, when the electron reflecting film is formed using the liquid for forming an electron reflecting film using the first aluminum phosphate as a binder, the pH of the electron reflecting film forming liquid becomes 1 to 3 due to the phosphate ion, so that the cold A compound is formed by reacting with iron on the surface of a base material made of a rolled steel plate. As a result, it is possible to obtain a film that is firmly attached to the base material and does not peel off.

The content of the tungsten oxide fine particles in the electron reflection film forming liquid is set to 15 to 50%.
If it is less than 15%, not only is it difficult to uniformly disperse, but also the landing shift of the electron beam on the phosphor screen due to the thermal expansion of the mask body, that is, the effect of suppressing the purity drift is reduced. Also 5
This is because if the content is more than 0%, the adhesive force of the film becomes insufficient, and defects due to the particles falling off tend to occur.

Although the thickness of the electron reflection film is set to 2 to 15 μm, if the thickness is less than 2 μm, the effect of suppressing the purity drift is reduced, and if the thickness is more than 15 μm, the hole of the opening of the mask body is reduced. This is because defects such as jams and the dropping of the tungsten oxide particles are likely to occur.

When the electron reflection film is formed by using the tungsten oxide particles, the high thermal emissivity and the electron reflection ability can improve the effect of suppressing the purity drift. That is, when the thermal emissivity of a perfect black body is 1, the thermal emissivity of bismuth oxide, which is conventionally known as the main component of an electron reflection film, is 0.80 to 0.85, and that of tungsten is 0.95 to 0.98. , Tungsten trioxide is 0.
92 to 0.95, which is equivalent to a film made of tungsten particles by using tungsten oxide particles containing tungsten trioxide as a main component, and has a higher thermal emissivity than a film made of triiron tetraoxide or bismuth oxide. An electron reflection film can be formed.

The following results were obtained when the characteristics were evaluated by actually incorporating the shadow mask manufactured by the above method into a 25-inch color picture tube.

An electron reflection film forming liquid containing 30% of tungsten oxide fine particles was applied to one surface of the mask body on the side of the electron gun, and the mask body was changed to an electron reflection film by baking at the same time when the oxide film was formed into a color picture tube. Built-in, anode voltage 26 k
As shown in FIG. 6, with a V and a cathode current of 1330 μmA, a strip-shaped white pattern 28 having a width of 88 mm was drawn at a position 160 mm away from the center of the phosphor screen 3 in the horizontal direction (X-axis direction), and after switching on, Phosphor screen 3 that changes with time due to thermal expansion of the shadow mask
The amount of movement of the electron beam above the center 2 of the white pattern 28
7 (point on the X-axis). As a result, as shown in Table 1, when the movement amount of the electron beam in the color picture tube in which the mask body without the electron reflection film is incorporated is 100%, the color image in which the mask body of this example is incorporated is received. In the case of the tube, the purity drift was 68%, and the purity drift could be improved by 32% with respect to the color picture tube incorporating the mask main body in which the electron reflection film was not formed.

[Table 1] Further, as a result of measuring the deterioration of the electron emission characteristics when the color picture tube is operated for a long time (life test), as shown in Table 2, a color picture tube in which a mask main body without an electron reflection film is incorporated is shown. 100% electron emission after 3000 hours
In such a case, the color picture tube incorporating the mask main body of this example provided characteristics substantially equal to 97%. Moreover, ion burning of the phosphor screen due to the gas in the tube was not recognized.

[Table 2]

[0038]

In a color picture tube in which an electron reflection film is formed on the electron gun side surface of a shadow mask having a cold-rolled steel sheet as a base material and the surface other than the electron reflection film formation portion is covered with an oxide film. When the electron reflection film is formed directly on the electron reflection film formation portion without forming an oxide film, particularly when the electron reflection film is formed by using the liquid for forming the electron reflection film with the first aluminum phosphate as a binder, A color picture tube in which phosphoric acid in the electron-reflecting film-forming liquid reacts with iron on the surface of a cold-rolled steel substrate to form a compound, and the electron-reflecting film has strong adhesion and does not peel off. You can

If an electron reflection film forming liquid is applied to a shadow mask before forming an oxide film, which has been molded into a predetermined shape and then washed, to form an electron reflection film forming film before forming an oxide film,
It is possible to form a uniform electron reflection film by eliminating uneven coating of the electron reflection film forming liquid.

Further, if the coating film for forming the electron reflection film is baked simultaneously with the formation of the oxide film to form the electron reflection film, the electron reflection film does not need a special baking step and therefore, a special baking furnace is not installed. The electron reflection film can be formed at the same time as the oxide film at the high temperature necessary for formation, and the high temperature baking can sufficiently secure the water of crystallization and the occluded gas of the material forming the cold-rolled steel sheet and the electron reflection film forming film. It is possible to obtain a color picture tube having excellent emission characteristics and withstand voltage characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a shadow mask of a color picture tube which is an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of the color picture tube.

FIG. 3 is a diagram showing a manufacturing process of the color picture tube.

FIG. 4 is a diagram showing a manufacturing process of the mask main body according to the embodiment of the present invention.

FIG. 5 is a manufacturing process diagram of a conventional mask main body shown for comparison with a manufacturing process of a mask main body according to an embodiment of the present invention.

FIG. 6 is a diagram for explaining measurement of an amount of movement of an electron beam on a phosphor screen due to thermal expansion of a shadow mask.

FIG. 7 is a diagram for explaining the configuration of a conventional color picture tube.

FIG. 8 is a diagram showing a configuration of a conventional shadow mask of a color picture tube.

[Explanation of symbols]

 3 ... Phosphor screen 5 ... Electron gun 6B, 6G, 6R ... 3 Electron beam 20 ... Shadow mask 22 ... Mask body 23 ... Mask frame 24 ... Electron reflection film

Claims (4)

[Claims] 1. A color picture tube in which an electron reflection film is formed on a surface of a shadow mask having a cold-rolled steel sheet as a base material on the electron gun side, and a surface other than the electron reflection film formation portion is covered with an oxide film. A color picture tube characterized in that the shadow mask has an electron reflection film directly formed on the electron reflection film formation portion without forming an oxide film. 2. The color picture tube according to claim 1, wherein the electron reflection film is formed of a film in which metal oxide particles are bound by a first aluminum phosphate. 3. An electron reflection film is formed on a surface of a shadow mask, which is made of a cold-rolled steel sheet as a base material and has a predetermined shape, on an electron gun side, and a surface other than the electron reflection film forming portion is covered with an oxide film. In the method for producing a color picture tube, the color image receiving method is characterized in that an electron reflection film forming liquid is applied to a shadow mask before forming an oxide film, which is molded into the predetermined shape and then washed to form an electron reflection film forming film. Pipe manufacturing method. 4. The method of manufacturing a color picture tube according to claim 3, wherein the electron reflection film forming coating formed by applying the electron reflection film forming liquid is baked to form an electron reflection film when the oxide film is formed. .