JP2002069547A - Composite material for vapor deposition and method for producing color cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material for vapor deposition having stable vapor deposition characteristics and capable of depositing a metal back film having high heat absorbability at a low cost. SOLUTION: This composite material for vapor deposition has a bar-shaped core material composed of a mixture of metal powder of aluminum or the like and carbon powder and an external material composed of metal such as aluminum provided so as to cover the core material and be adhered thereto. By subjecting the composite material for vapor deposition to vacuum deposition, a metal back film having a first vapor deposited layer of pure aluminum and a co-vapor deposited layer of aluminum and carbon formed thereon can be obtained. Then, the doming of a shadow mask in a color cathode ray tube can remarkably be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material for vapor deposition and a method for manufacturing a color cathode ray tube, and more particularly to a composite material for vapor deposition for forming a metal back film having high heat absorption on a phosphor screen inside a panel. And a method for manufacturing a color cathode ray tube having a metal back film having high heat absorption.

[0002]

2. Description of the Related Art In general, a shadow mask type color cathode ray tube is provided in a vacuum envelope (glass bulb) made of glass with an electron gun for generating three electron beams and a blue and green electron beam. , A phosphor screen that emits light of three colors, red, and a shadow mask that performs color selection so that three electron beams are projected on the phosphor layers of the corresponding colors. A metal back layer such as an aluminum (Al) film is formed on the phosphor layer by a method such as vacuum deposition. The metal back layer plays a role of, among the light generated in the phosphor layer, reflecting the light traveling toward the electron gun to the panel side to increase the brightness and stabilizing the potential of the phosphor layer. Further, it has a function of preventing the phosphor layer from being damaged by ions generated by ionization of gas remaining in the vacuum envelope.

In such a color cathode ray tube, a shadow mask is disposed so as to face a phosphor screen formed on the inner surface of the panel, and passes through a large number of openings (or openings such as slits) provided on the entire surface. The electron beam emitted from the gun is landed only on the phosphor layer which has a geometrical one-to-one relationship with the aperture.

Therefore, if the geometrical positional relationship between the aperture of the shadow mask and the phosphor layer is shifted, the electron beam cannot be landed at a correct position.
Correct color display cannot be performed. One of the causes of such mislanding of the electron beam is deformation of the shadow mask due to thermal expansion.

That is, the effective electron beam amount of the electron beam that passes through the opening of the shadow mask is about 20%, and the remaining about 80% of the electron beam collides with the shadow mask, is absorbed, and has thermal energy. To increase the temperature of the shadow mask. As a result, the shadow mask thermally expands during operation, causing a deformation called doming. As a result, the distance between the opening of the shadow mask and the phosphor layer changes, and color drift (purity drift) occurs on the screen.

[0006] The doming is classified into a whole doming due to a rise in temperature of the entire shadow mask and a local doming in which a part of the shadow mask is thermally deformed particularly when a large amount of electron beam is transferred in the screen. The whole doming includes short-time doming and long-time doming. In short-time doming, only the shadow mask is rapidly heated immediately after the operation starts and thermally expands.On the other hand, the mask frame having a large heat capacity does not thermally expand. Moves in the direction of the radius of curvature. In long-time doming, the mask frame having a large heat capacity thermally expands together with the shadow mask, so that the opening moves in a direction perpendicular to the tube axis.

On the other hand, local doming may occur at any time during the operation, and the aperture of the shadow mask is moved in the direction of the radius of curvature similarly to short-time doming. Large deformation.

In recent years, as a monitor terminal of a computer or a workstation, the use ratio of a display using a liquid crystal has been increasing from the viewpoint of flatness of the panel surface and space saving, and in contrast thereto, the panel surface has a flat surface. Flat-type CRTs and wide-angle CRTs with a reduced depth have been developed. In addition, consumer TV
As cathode ray tubes for use have become larger and wider, and from the ergonomic point of view, flat-type cathode-ray tubes having a flat screen with little reflection of external light and little image distortion have appeared, and are rapidly spreading.

[0009] In these color cathode ray tubes, not only the outer surface of the panel becomes flat, but also the inner surface of the panel approaches flat. Since the shadow mask is formed to match the curvature of the inner surface of the panel, the curvature of the shadow mask must be reduced with the flattening of the panel, and as a result, the doping characteristics of the shadow mask are greatly deteriorated. Had occurred.

[0010] That is, while the conventional design of the mask frame system and the lens design at the time of exposing the phosphor screen could prevent the entire doming, the flat-type color cathode ray tube can no longer cope with it. Also, with respect to local doming where it is difficult to take measures due to the design of the mask frame system, the deformation amount increases as the shadow mask approaches flat.

Conventionally, in order to suppress doming due to thermal expansion of a shadow mask, a dispersion liquid of graphite is applied and dried on a metal back film formed on a phosphor screen to form a film having high heat absorption (high heat absorption). A film is formed to promote heat radiation from the shadow mask and to reduce the temperature of the shadow mask.

[0012]

However, according to this method, not only a step for forming a high heat absorbing film is added, but also the formed high heat absorbing film is easily peeled off and dropped off, thereby lowering the product yield. In addition, there is a problem that a breakdown voltage failure during use is caused.

As a countermeasure against such a problem, a method of forming a high heat absorbing film by vacuum-depositing a pellet obtained by sintering a mixture of an aluminum powder and a carbon powder by hot pressing on a metal back film has been proposed. JP 11
No. 2,138,884. However, in this method, it is difficult to form a metal back film having good characteristics because the vapor deposition characteristics are liable to fluctuate due to oxidation of aluminum and moisture adsorption of carbon. In addition, evaporation residues were likely to remain.

Further, Japanese Patent Application Laid-Open No. 11-236634 discloses a method for producing a deposition material comprising a mixture of aluminum powder and carbon powder and having improved deposition characteristics. Is 50 times as large as the conventional Al vapor deposition material, so that it has been difficult to use it for mass production. In either method, the number of deposition boats is doubled and the conditions are changed in order to form a heat absorbing film made of Al and carbon on a metal back film formed by a method such as ordinary vapor deposition. It is necessary to perform vapor deposition or double the vapor deposition position. Therefore, there has been a problem that the cost and work load in the vapor deposition process increase.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and a composite material for vapor deposition capable of forming a metal back film having stable vapor deposition characteristics, low cost and high heat absorption, and a heat absorbing material. It is an object of the present invention to provide a method for manufacturing a color cathode ray tube having a metal back film having high performance.

[0016]

According to a first aspect of the present invention, there is provided a composite material for vapor deposition, comprising: a core material comprising a mixture of a metal powder and a carbon powder; And an exterior material made of metal provided.

In the composite material for vapor deposition of the present invention, as described in claim 2, it is desirable to use aluminum or aluminum alloy powder as the metal powder.
Further, as described in claim 3, it is desirable that the exterior material is made of aluminum or an aluminum alloy.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a color cathode ray tube, wherein a phosphor layer is formed on an inner surface of a translucent panel, and a metal back film is formed on the phosphor layer. A method of manufacturing a color cathode ray tube comprising the steps of: performing vacuum deposition using the composite material for deposition according to claim 1 in the step of forming the metal back film. In such a method of manufacturing a color cathode ray tube, as described in claim 5, the composite material for vapor deposition is made of a core material made of a mixture of aluminum or aluminum alloy powder and carbon powder, and It is desirable to have an exterior material made of aluminum or an aluminum alloy which covers the material and is provided in close contact with the exterior material.

In the case where the composite material for vapor deposition of the present invention is used and vacuum vapor deposition is carried out by a normal resistance heating method, first, the metal (aluminum or aluminum alloy) constituting the exterior material is melted and evaporated, and then, The mixture of the carbon powder and the metal powder such as aluminum constituting the core material evaporates in vacuum. Regarding the deposition of the core material, the melting point of carbon is extremely high at 3500 ° C. or higher, and carbon cannot evaporate alone at a normal heating temperature (about 700 ° C.), but was mixed with a metal powder such as aluminum. When heated in a state, it is considered that the carbon powder evaporates while being held in the metal powder. That is, the metal particles act as a carrier of the carbon particles, and when the metal particles evaporate, they embrace the carbon particles and evaporate in a vacuum, so that the metal particles and the carbon particles are deposited (co-deposited) at a temperature of about 700 ° C. be able to.

In this way, first, a first vapor-deposited layer made of a metal such as aluminum constituting the exterior material is formed, and a co-deposited layer of a metal such as aluminum and carbon is formed thereon, thereby completing a metal back film. I do. The co-deposition layer is
It contains carbon with high heat absorption and is extremely excellent in heat absorption (heat release). Note that the boundary between the first evaporation layer and the co-evaporation layer formed thereover is not always clear.

As described above, by using the composite material for vapor deposition of the present invention, the original function as a metal back film such as stabilization of the reflection of light emission from the phosphor and the potential is maintained. A metal back film that is stable and has high heat absorption without falling off can be obtained. Therefore, doming of the shadow mask in the color cathode ray tube can be largely suppressed.

In addition, by simply changing the deposition source of aluminum or the like conventionally used for forming a metal back film to the composite material for deposition of the present invention, it is possible to obtain a high heat absorption rate without adding or changing a large process. Metal back film can be formed. Furthermore, the composite material for vapor deposition of the present invention can be manufactured at a price equivalent to that of a conventional material for vapor deposition of aluminum.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a composite material for vapor deposition according to the present invention. In this figure, reference numeral 1 indicates a round bar-shaped core member made of a mixture of metal powder and carbon powder, and reference numeral 2 indicates a cylindrical metal member provided so as to cover the core member 1 in close contact. Shows the exterior material (sleeve).

In the composite material for vapor deposition of the embodiment, the metal constituting the exterior material 2 is mainly aluminum or aluminum and a small amount of magnesium (M
g) and alloys containing metals such as manganese (Mn). However, when the metal back film is formed, it is not limited to the metal such as aluminum as long as it does not degrade the characteristics of the phosphor of the lower layer, has a small electron reflection coefficient, and is highly extensible. can do.

Further, as the metal powder constituting the core material,
The use of the aluminum or aluminum alloy powder described above is optimal. However, any metal can be used as the metal back film as long as the metal does not deteriorate the characteristics of the phosphor, has a small electron reflection coefficient, and is highly malleable.

The metal powder constituting the core material preferably has an average particle diameter of 10 to 100 μm and a maximum particle diameter of 250 μm or less. The carbon powder preferably has an average particle diameter of 30 μm or less and a maximum particle diameter of 80 μm or less. When the particle diameters of the metal powder and the carbon powder are out of the above range, the metal and the carbon cannot be co-evaporated efficiently. In particular, it is desirable that the carbon powder be made as small as possible in particle size and dispersed uniformly with the metal powder so that the metal particles can easily embrace the carbon particles during evaporation.

The mixing ratio of the carbon powder in the mixture constituting the core material is desirably 2 to 10% (% by mass). If the proportion of the carbon powder is less than 2%, a metal back film having a sufficiently high heat absorbing property cannot be obtained. On the other hand, when the proportion of the carbon powder exceeds 10%, not only does the extensibility in producing the composite material for vapor deposition decrease significantly, but also it becomes difficult for metal and carbon to co-deposit at the time of vapor deposition, resulting in an increase in residues. Therefore, it is not preferable.

In order to manufacture such a composite material for vapor deposition, first, a metal powder and a carbon powder from which adsorbed components have been sufficiently removed are mixed and formed into a round bar shape. Insert into a metal cylinder and fill it without gaps. When inserting and filling the molded body serving as the core material, one end of the cylindrical body is sealed, the internal air is removed from the other end, and then this end is also sealed. The operation of removing the air inside is for obtaining a stronger adhesion between the core material and the exterior material.

Next, the composite material into which the molded body has been inserted and filled is drawn to integrate the molded body and the cylindrical body. Here, the drawing condition may be any of cold, warm and hot, but it is necessary to pay sufficient attention to the oxidation of the surface so as not to impair the deposition characteristics.

By performing vapor deposition using the composite material for vapor deposition of the embodiment constructed as described above, it is possible to maintain desired characteristics as a metal back film, such as stabilizing the reflection of light emitted from the phosphor and the potential. In addition, a stable and highly heat-absorbing metal back film can be formed without peeling or falling off during use. Therefore, doming of the shadow mask of the color cathode ray tube can be largely suppressed.

Further, by simply changing the aluminum evaporation source conventionally used for forming the metal back film to the composite material for evaporation of the embodiment, it is possible to obtain a high heat absorption coefficient without adding or changing a large process. A metal back film can be formed. Furthermore, the composite material for vapor deposition can be manufactured at a price equivalent to that of a conventional material for vapor deposition of aluminum.

Next, a color cathode ray tube having a metal back film formed using such a composite material for vapor deposition will be described with reference to the drawings.

As shown in FIG. 2, the color cathode ray tube has a glass panel 3, a funnel 4 and a neck 5.
And has an envelope whose inside is kept in a vacuum. An electron gun 6 for emitting three electron beams 6a is arranged inside the neck 5 of the envelope, and a deflecting device 7 for deflecting the electron beam 6a by the generated magnetic field is arranged outside the funnel 4. Have been.

On the inner surface of the panel 3, a phosphor screen 10 composed of a black matrix 8 and a phosphor layer 9 is formed, as shown in FIG. Are formed. This metal back film 11 is formed by performing vacuum deposition using the composite material for vapor deposition of the above-described embodiment.
It has the following structure. That is, a first vapor deposition layer 11a formed by vapor deposition of a metal such as aluminum constituting an exterior material of a composite material for vapor deposition, and a co-vapor deposition layer of a component constituting a core material formed thereon (such as aluminum) The metal back film 11 is constituted by the co-evaporation layer of metal and carbon) 11b. Metal back film 11
The overall thickness is desirably 0.1 to 0.5 mm.

Further, inside the panel 3, a shadow mask 12 that performs color selection so that the three electron beams 6 a impinge on the phosphor layers of the corresponding colors respectively faces the phosphor screen 10. Are located. A mask frame 13 is provided around the shadow mask 12 (skirt portion).
The mask frame 13 is locked to a stud pin 14 fixed to the inner wall surface of the panel 3 via a spring 15 or the like. Note that a color filter (not shown) having a color corresponding to the emission color of the phosphor is provided between the phosphor screen 10 and the panel 3 in order to improve luminance, contrast, emission chromaticity, and the like. it can.

In such a color cathode ray tube, a metal back film 11 which has a desired function, is stable and has high heat absorption without peeling or falling off during use is formed on the phosphor screen 10. The shadow mask 12
Can be significantly suppressed.

Next, the present invention will be further described based on specific examples.

Example Nitrogen gas atomization A having an oxygen content of 1000 ppm or less
1 powder (maximum particle size 150 μm, average particle size 70 μm) and carbon powder having a maximum particle size of 50 μm and an average particle size of 5 μm were prepared. For carbon powder, 15
Heating and drying were performed at a temperature of 0 to 300 ° C. to sufficiently remove the adsorbed moisture. And these powders are converted to Al powder:
After mixing in an inert gas atmosphere at a carbon powder ratio of 9.2: 0.8 (mass ratio), the mixed powder was molded using a hydraulic press to form a round bar having an outer diameter of 5 mm and a length of 30 cm. A molded article was obtained.

On the other hand, as an exterior material, an inner diameter of 5 mm and an outer diameter of 12
A cylindrical sleeve made of pure Al (purity: 99.9%) having a length of 35 cm and a length of 35 cm was prepared.

Next, the Al-made sleeve was pickled to remove an oxide film and dirt on the surface, and then a molded body made of a mixture of Al powder and carbon powder was inserted into the hollow. Then, after sealing one end of the Al sleeve and removing the internal air from the other end, this end was also sealed.

Next, for the composite material thus obtained,
Cold drawing was performed as described below. That is, this composite material is repeatedly subjected to drawing while selecting a drawing die so that the processing rate at one time is 5 to 10% in a reduction rate of a cross-sectional area, and a composite material for vapor deposition having an outer diameter of 1.7 mm is obtained. Obtained. In the embodiment, the cold drawing is performed. However, the drawing may be performed hot or hot.

Next, the obtained composite material for vapor deposition was cut into a predetermined length and subjected to vapor deposition. That is, the vapor-deposited composite material cut into a predetermined length was supplied to a resistance heating type vapor deposition boat, and a panel having a phosphor layer formed on the inner surface was placed in a vacuum chamber. And evacuate the vacuum chamber,
When the degree of vacuum reached a predetermined value, energization of the evaporation boat was started.

First, the vapor deposition boat is pre-heated to exhaust the occluded gas, and then heated (mainly heated) to a temperature of about 700 ° C. to vapor-deposit the composite material for vapor deposition to form a film on the phosphor layer. A metal back film of 0.1 to 0.5 mm was formed.

The metal back film thus formed has a first vapor-deposited layer made of pure Al derived from an Al sleeve (outer material) formed first, and a co-deposit of Al and carbon, which was vapor-deposited and formed later. And layers. The heat absorption rate of the obtained metal back film was 0.25, which was extremely higher than the heat absorption rate (0.16) of the pure Al metal back film. Almost no evaporation residue was found.

[0045]

As is clear from the above description, according to the composite material for vapor deposition of the present invention, the metal back film retains the characteristics originally required, does not fall off during use, is stable and has a high heat absorption rate. A metal back film can be obtained. Therefore, by using such a metal back film, doming of the shadow mask in the color cathode ray tube is largely suppressed, and display reliability is improved.

Further, it is only necessary to change the Al material conventionally used for forming the metal back film to the composite material for vapor deposition of the present invention, and it is not necessary to add or change a large process, and the metal having a high heat absorption rate can be obtained. A back film can be formed. Furthermore, in the composite material for vapor deposition of the present invention, the composite material for vapor deposition of the present invention can be manufactured at a price equivalent to that of a conventional material for vapor deposition of aluminum.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of an embodiment of a composite material for vapor deposition according to the present invention.

FIG. 2 is a cross-sectional view showing a schematic configuration of an embodiment of a color cathode ray tube according to the present invention.

FIG. 3 is a cross-sectional view showing a structure of a metal back film formed using the composite material for vapor deposition of the example.

[Explanation of symbols]

1 core material made of a mixture of a metal powder such as aluminum and carbon powder 2 cylindrical exterior material made of a metal such as aluminum 3 panel 4 funnel 6a electronic Beam 6 Electron gun 7 Deflector 10 Phosphor screen 11 Metal back film 11a First vapor deposition layer 11b Co-deposition layer 12 Shadow mask 13 ...... Mask frame

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshihiro Tajima 1-9-2, Harara-cho, Fukaya-shi, Saitama F-term in the Fukaya Plant of Toshiba Corporation (reference) 4K018 AA15 AB07 AC01 BC12 CA11 JA21 KA32 4K020 AA24 AC01 BB29 4K029 AA09 AA26 BA03 BA34 BA64 BD00 CA01 DB03 DB04 DB05 DB08 DB10 5C028 CC03 CC04 CC05 5C060 AA01 AA04 BC01 CJ07 JA12

Claims (5)

[Claims] 1. A composite material for vapor deposition comprising: a core material made of a mixture of a metal powder and a carbon powder; and an exterior material made of a metal provided so as to cover and closely contact the core material. 2. The method according to claim 1, wherein the metal powder is aluminum or an aluminum alloy powder.
The composite material for vapor deposition according to the above. 3. The composite material for vapor deposition according to claim 1, wherein the exterior material is made of aluminum or an aluminum alloy. 4. A method for manufacturing a color cathode ray tube, comprising: a step of forming a phosphor layer on an inner surface of a translucent panel; and a step of forming a metal back film on the phosphor layer. 3. A method for manufacturing a color cathode ray tube, comprising performing vacuum deposition using the composite material for vapor deposition according to claim 1 in the step of forming. 5. A core material comprising a mixture of a powder of aluminum or an aluminum alloy and a carbon powder, and a cladding material comprising aluminum or an aluminum alloy provided so as to cover and closely contact the core material. 5. The method for producing a color cathode ray tube according to claim 4, comprising: