JPH03205742A - Color picture tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the deterioration of withstand voltage characteristics and the clogging of a shadow mask by providing FeO or an oxide film containing FeO on the surface of a substrate mainly made of iron on at least one of a mask main body, a mask frame and an inner magnetic shield body. CONSTITUTION:At least one of a mask main body 14, a mask frame 15 and an inner magnetic shield body 19 after the final production heating process is formed with a substrate mainly made of iron, and FeO or an oxide film containing FeO is provided on the surface of the substrate. The FeO film component in the oxide film formed on inner metal components such as the mask main body 14, mask frame 15 and inner magnetic shield body 19 is left in the oxide film after the heating in the atmosphere during the normal color picture tube production process and the exhausting and sealing. Such actions as the increase of the radiation action and the reduction of reflected electron beams during the operation of a color picture tube are not impaired, and no oxide film is peeled even if vibrations and shocks occur during the operation or handling of the tube. The deterioration of withstand voltage characteristics and the clogging of a shadow mask can be prevented.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a color picture tube, and particularly relates to an internal magnetic shield for shielding an external magnetic field, a shadow mask, a mask frame, etc. The present invention relates to a color picture tube including metal parts and a method for manufacturing the same.

(Prior Art) Generally, in a color picture tube, a phosphor screen consisting of three-color phosphor layers that emit blue, green, and red light is formed on the inner surface of the panel of an envelope. A shadow mask is mounted on the inside of the mask body, which includes a mask body having a large number of electron beam passage holes formed therein, and a mask frame that supports the periphery of the mask body. Three electron beams emitted from an electron gun installed in the neck of the funnel integrated with the panel are deflected by the magnetic field of a deflection device installed outside the funnel, and the phosphor screen is scanned horizontally and vertically. By doing so, the structure is formed to display a color image.

In such a color picture tube, in order to correctly display a color image on the phosphor screen, the three-color phosphor layer and the electron beam passage hole of the shadow mask must have a predetermined matching relationship. Even if the color phosphor layer and the electron beam passage hole of the shadow mask are arranged in a matching relationship,
Note that the electron beam emitted from the electron gun is affected by external magnetic fields such as earth's magnetism, and may not land correctly on the three-color phosphor layer, resulting in deterioration of color purity. Therefore, in order to prevent this deterioration of color purity, there are some mask frames in which a magnetic shield is attached to the mask frame and extends inside the funnel cone, which is most susceptible to the influence of external magnetic fields. This magnetic shield is called an internal magnetic shield because it is placed inside the pipe.

This internal magnetic shield is made of a ferromagnetic metal material and is formed into a hollow trapezoidal shape so as to extend along the inner surface of the funnel.

In order to make the magnetic shielding effect effective for such an internal magnetic shield, it is preferable to use a material that has magnetic properties that easily magnetizes even in a weak magnetic field such as earth's magnetism, and easily demagnetizes outside the magnetic field. The internal magnetic shield having such magnetic properties is formed, for example, by press-forming a steel plate made of a ferromagnetic metal mainly composed of iron, after sufficiently annealing it in a decarburizing atmosphere. However, in general, when ferromagnetic metal sheet materials are sufficiently annealed in a decarburizing atmosphere, the material strength decreases due to the heat treatment, and it becomes easily deformed during handling during subsequent forming and tube assembly processes. , it is not possible to anneal sufficiently, and it is not possible to obtain a product that satisfies the required magnetic properties.

On the other hand, the metal parts inside the tube, such as the mask body, mask frame, and internal magnetic shield of a color picture tube, are made of a steel plate whose main component is iron, and a black oxide film is formed on the surface thereof. This black oxide film is used to prevent rust on the metal parts inside the tube, increase heat dissipation during tube operation, and reduce reflected electron beams. After degreasing and cleaning, it is heated in a black oxidation furnace in an H2-H20 mixed gas atmosphere at 500 to 650°C, or by heating to about 600°C in a CO2 atmosphere.

However, as shown in FIG. 7(a), the oxide film on the substrate (1) mainly made of iron (Fe) formed by the above-mentioned conventional method contains not only black Fe 3 04 (2) but also , with red rust F e2 03 (3), consisting of a two-layer structure or a mixed layer thereof. Therefore, if the internal magnetic shield after forming an oxide film is stored in the atmosphere, or if it is heated in a furnace with an atmosphere of around 450°C during the manufacturing process of color picture tubes, the oxide film will be removed from the atmosphere. Further oxidation reaction occurs depending on the temperature and temperature, and as shown in Figure 7(b), part of Fe304(2) becomes Fe203(3).
Changes to

Therefore, the antirust effect often decreases. Also, F e 3 04 (2) and F e 2 03 (3)
Voids may be included in the oxide film made of This may cause deterioration of withstand voltage characteristics and clogging of electron beam passage holes in the shadow mask. This problem is caused by the progress of oxidation, which causes F e203
The more (3) increases, the more likely it is to occur.

(Problems to be Solved by the Invention) As described above, a color picture tube includes metal parts inside the tube such as a mask body, a mask frame, and an internal magnetic shield made of a steel plate containing iron as a main component. A black oxide film is formed on the surface, but conventionally this oxide film was Fe30
4 and Fe203+7) because it is a two-layer or mixed layer,
The rust prevention effect is insufficient, and the film peels off due to low film adhesion strength, resulting in deterioration of withstand voltage characteristics and clogging of electron beam passage holes in the shadow mask. In addition, especially regarding the internal magnetic shield, it does not necessarily satisfy the required magnetic properties due to problems with material strength.

This invention was made in view of the above problems, and
The purpose is to form a black oxide film with high adhesion strength on the surface of a substrate whose main component is iron.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a shadow mask consisting of a mask body in which a large number of electron beam passage holes are formed inside a panel, and a mask frame that supports the peripheral portion of this mask body. A color picture tube mounted on a mask frame and having an internal magnetic shield extending inside a funnel integral with the panel, wherein at least one of the mask body, the mask frame, and the internal magnetic shield after undergoing a final manufacturing heating process. One is a color picture tube which is made of a substrate mainly made of iron and has an oxide film containing FeO or FeO on the surface of the substrate.

Furthermore, a shadow mask consists of a mask body with a large number of electron beam passage holes formed inside the panel, a mask frame that supports the peripheral part of this mask body, and a funnel attached to the mask frame and integrated with the panel. A method for manufacturing a color picture tube having an inner tube metal part consisting of an extending internal magnetic shield, wherein at least one of the tube inner metal parts is heated to 800 to 1
A first heating step of rapidly heating at a temperature of 000°C, a step of rapidly cooling in a neutral atmosphere, and a second heating step of performing at least one heat treatment in an air atmosphere at a temperature of 300°C to 500°C.
The process consists of a heating process of
This is a method of manufacturing a color picture tube in which an oxide film containing O or FeO is formed.

(Function) In the present invention, FeO in the oxide film formed on the pipe internal metal parts such as the mask body, mask frame, internal magnetic shield, etc.
The film components remain in the oxide film even after being heated in the atmosphere in the normal color picture tube manufacturing process, evacuated, and sealed. It does not impair the mitigation effect, and the oxide film does not peel off even if there is vibration or shock during pipe operation or handling. Therefore, it is possible to prevent deterioration of withstand voltage characteristics and clogging of holes in the shadow mask.

In the present invention, in order to maintain the FeO film even after the color picture tube is completed, the FeO film after the oxide film is formed and the F
The ratio to the e203 film is important.

That is, an oxide film containing FeO is formed by exposing a substrate mainly composed of iron to an oxidizing or decarburizing atmosphere, such as CO2 or H2-
It is obtained by rapidly heating at a temperature of 800 to 1000°C in an H20 atmosphere and then rapidly cooling.
If the FeO content in the film having a thickness of 50% or more is 50% or more of the total oxide film components including Fe203 and Fe304 components, the FeO film will remain even if heated in the air during the tube manufacturing process. This is because if the FeO component in the total oxide film component after oxide film formation is large, the oxidation reaction time to become Fe203 will be longer even if heating is performed in the air during the tube manufacturing process, and the oxidation will apparently progress. This is because it becomes difficult.

The resulting oxide film is a dense film with extremely few voids and has excellent adhesion to the substrate.

Previously, JP-A No. 55-19715, page 1, right column No. 1
As stated in line 6 to line 1 of the left column of page 2,
It is generally believed that it is undesirable to leave the FeO film as it causes poor vacuum quality, and after the oxide film is formed, it is not stored in the atmosphere or heated in the atmosphere during the normal color picture tube manufacturing process. It has been common knowledge that if this is done, no FeO film will remain, but the present invention differs from the conventional technical idea in that it actively leaves this FeO film.

When forming an oxide film, if the FeO component is less than 50% of the total oxide film component, the FeO film will decrease due to heating in the oxidizing atmosphere during the color picture tube manufacturing process, which is undesirable since the oxide film adhesion strength during tube operation will decrease. .

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a color picture tube which is one embodiment of the present invention. This color picture tube has an envelope consisting of a substantially rectangular panel (IO) and a funnel-shaped funnel (11) integrally joined to the panel (IO).
A phosphor screen (l2) consisting of a three-color phosphor layer that emits blue, green, and red light is formed on the inner surface, and a shadow mask (l3) is formed on the inside facing and close to this phosphor screen (l2). is attached by a mask support means (not shown). This shadow mask (13) consists of a mask body (14) in which a large number of electron beam passage holes are formed and a mask frame (work 5) that supports the peripheral portion thereof.

In addition, an electron gun (l8) that emits three electron beams (17B).(17G).(17R) is installed in the neck (IB> of the funnel (1l). 3 electron beams (17B) emitted from
, (17G), (17R) from external magnetic fields such as geomagnetism is attached to the mask frame (I5) and the funnel <1
Cone I (20) of 1) extends inside. This internal magnetic shield (19) is usually formed into a hollow trapezoidal shape, as shown in FIG.

The mask body (l) constituting the shadow mask (l3)
4), mask frame (l5) and internal magnetic shield (
l9) are all based on steel plates whose main component is iron,
A black oxide film is formed on its surface.

In the color picture tube of the present invention, the substrate (
1) FeO film (22) is formed in close contact with the surface, and Fe304 film (2) and Fe2 are formed on the surface layer of this FeO film (22).
03 film (3) exists.

In the present invention, in order to maintain the FeO film even after the color picture tube is completed, the FeO film after the oxide film is formed and the F
The ratio to the e203 film is important.

That is, an oxide film containing FeO is formed by exposing a substrate mainly composed of iron to an oxidizing or decarburizing atmosphere, such as CO2 or H2-
It is obtained by rapidly heating at a temperature of 800 to 1000°C in an H20 atmosphere and rapidly cooling, but the F in the film obtained at this time is
If the eO component is 50% or more of the total oxide film components including Fe203 and Fe304 components, the FeO film will remain even if heating is performed in the air during the tube manufacturing process. This is because there is a large amount of FeO in the total oxide film components after the oxide film is formed, so even if heating in the atmosphere during the tube manufacturing process is performed, Fe2
This is because the oxidation reaction time until reaching 03 becomes longer and the oxidation appears to be in a state where it is difficult to proceed.

4 and 5 are conceptual diagrams of the FeO film and Fe203 film after the oxide film is formed according to the present invention, and FIG. 4 shows the substrate (1
) A film in which only the FeO film (22) is formed on the surface, and FIG. 5 shows a mixed film with Fe304 film (2) and Fe203 film (3).

Figure 6 shows FeO in the total oxide film components during oxide film formation.
It is a diagram showing the residual FeO component ratio after performing heating in the air at 450° C. for 30 minutes, which corresponds to heating in the air atmosphere in the tube manufacturing process, with the component ratio on the horizontal axis. It can be seen from the figure that the larger the FeO fraction in the total oxide film components at the time of oxide film formation, the larger the residual FeO component ratio after heating in the atmosphere. When we conducted a film peeling test using cellophane tape on the samples after heating, we did not find any film with an FeO film component ratio of 50% or more during film formation, and no film peeling occurred even in the forced test when the FeO film component ratio was 80% or more. .

On the other hand, in the case of less than 50%, film peeling was observed.

Next, an example of the internal magnetic shield will be specifically explained. The main component is iron, with 0 of each of C, Si, Mn, and S.
．． An ingot containing 5% by weight or less of P and approximately 0.2% by weight of P is annealed and cold-worked repeatedly to produce a steel plate with a thickness of 0.15mm. This steel plate is rapidly heated at 900°C in a CO2 atmosphere furnace, and N2 Rapidly cool in a neutral atmosphere such as atmosphere. Rapid heating in this case means 200'C/Bil1 or higher, followed by rapid cooling at 150°C/min or higher.

As a result, the grain size of the steel sheet was found to be the grain size No. defined in the JIS G 0552 Frite Grain Size Testing Method. is 4-6
A mild steel strip with a black oxide film and a coercive force (HC) of 1.100e was obtained. As a result of investigating the oxide film on the surface by X-ray diffraction method and cross-sectional observation,
It was confirmed that the film was an FeO film with a thickness of 2 to 3 μm. This mild steel strip was then press-formed to form an internal magnetic shield, and after degreasing and cleaning, a peel test was performed using cellophane tape on the press-formed bent portion to examine the adhesion strength. It was confirmed that the adhesion strength of the film was significantly improved compared to the oxide film of the conventional internal magnetic shield.

Inoko's magnetic shielding plate was incorporated into a color picture tube and heated to 450℃3.
After the tube was completed through a heating process in the air for 0 minutes, the oxide film was examined and the presence of an FeO film was confirmed as shown in FIG.

As a result of a peeling test of the membrane using cellophane tape, no peeling of the membrane was observed.

On the other hand, when conventional internal magnetic shields are heat-treated at high temperatures, the material strength decreases and deforms during molding or assembly into color picture tubes, which poses a practical problem.
It takes a long time to decarburize at a relatively low temperature of ℃, and as a result, the grain size of the crystals is no. is 8 to 10, and the coercive force is also 3
It is about 0e, which is not very good, and the oxidation film that is formed progresses over time and becomes Fe containing voids.
304 film, which has poor adhesion to the substrate and causes peeling of the film during molding, making it necessary to form an oxide film after molding.

Next, the effect of P in the present invention will be explained.

In the present invention, it has been found that adding a certain amount of P to the substrate further improves the adhesion strength of the oxide film. According to experiments, when the oxide film of the present invention was applied to a product with a small amount of P added, film peeling was observed in a film peeling test using a cellophane tape, but no peeling was observed when the P content was 0.1% or more. It is presumed that the high film adhesion strength of the P-added product is due to the anchoring effect of P diffused into the oxide film.

Further, in the present invention, heating at a temperature of 800° C. or higher is preferable in order to form an oxide film, but such high-temperature heating tends to cause a decrease in the strength of the substrate. In this case, in order to prevent a decrease in strength, it is generally considered to add a large amount of St, Mn, Mo, V, etc. However, although these additions can prevent a decrease in strength, they do cause deterioration in magnetic properties. This is because intermetallic compounds with poor magnetic properties are generated at grain boundaries.

In the present invention, P is added in a small amount, preferably 0.1% to 0.2%.
If % is added, the decrease in strength will be reduced and no deterioration of magnetic properties will occur. P is probably because intermetallic compounds with poor magnetic properties are not generated within this range.O [Effects of the invention] The mask body, mask frame, and internal magnetic shield that constitute the shadow mask that have passed through the manufacturing heating process of color picture tubes. If at least one of the substrates is made of a substrate whose main component is iron and has an oxide film containing FeO or FeO, the oxide film will have a high adhesion strength and adhere to the substrate, and will have a heat dissipation effect during operation of the color picture tube. It is possible to prevent deterioration of withstand voltage characteristics and clogging of the electron beam passage hole in the shadow mask without sacrificing effects such as increasing the electron beam and reducing reflected electron beams, greatly improving the quality of color picture tubes. be able to.

[Brief explanation of drawings]

1 to 5 are explanatory diagrams of embodiments of the present invention.
The figure shows the configuration of a color picture tube, which is an example of this.
Figure 2 is a perspective view showing the structure of the internal magnetic shield, Figure 3 is a perspective view showing the structure of the internal magnetic shield.
The figure shows the structure of the oxide film formed on the surface of the internal magnetic shield, Figure 4 shows the basic structure of the oxide film to be formed on the surface of the internal magnetic shield, and Figure 5 is a diagram showing the structure of the oxide film actually formed, and Figure 6 shows the FeO component ratio in the total oxide film components at the time of oxide film formation on the horizontal axis.
Figures 7(a) and 7(b), which show the residual FeO component ratio after heating in the air at 450°C for 30 minutes in the tube manufacturing process, are made of steel bodies such as conventional internal magnetic shields, respectively. FIG. 2 is a diagram showing the structure of an oxide film formed on a substrate, and a diagram showing the structure of an oxide film that is then heated in the air to cause an oxidation reaction. lO...Panel 13...Shadow mask l5...Mask frame 11...Funnel 14...Mask body l9...Internal magnetic shield

Claims (2)

[Claims] (1) A shadow mask consisting of a mask body with a large number of electron beam passage holes formed inside the panel and a mask frame that supports the peripheral part of this mask body is attached,
In a color picture tube in which an internal magnetic shield extending inside a funnel integral with the panel is attached to the mask frame, at least one of the mask body, the mask frame, and the internal magnetic shield after undergoing a final manufacturing heating process. 1. A color picture tube characterized in that the substrate is made of a substrate mainly composed of iron, and has an oxide film containing FeO or FeO on the surface of the substrate. (2) A shadow mask consisting of a mask body with a large number of electron beam passage holes formed inside the panel, a mask frame that supports the peripheral part of this mask body, and a shadow mask that is attached to the mask frame and integrated with the panel. In a method for manufacturing a color picture tube having a tube inner metal part consisting of an internal magnetic shield extending inside a funnel, at least one of the tube inner metal parts is heated at 800 to 1000°C in an oxidizing or decarburizing atmosphere. A first heating step of rapidly heating at a temperature of 300~
a second heating step of performing at least one heat treatment in an air atmosphere at a temperature of 500° C., and forming an oxide film containing FeO or FeO on the base surface of the metal part inside the tube. A method of manufacturing a picture tube.