JPH0817070B2 - Method for forming blackened aluminum thin film of color picture tube - Google Patents

Description

The present invention relates to a blackened aluminum thin film for a color picture tube in which a blackened aluminum thin film is formed on a light-reflecting metal thin film deposited on the inner surface of a glass face plate. It relates to a forming method.

[Conventional technology]

The fluorescent surface of the color picture tube, the light emitted from the fluorescent film adhered to the inner surface of the glass face plate forming the front surface of the glass tube, the front of the color picture tube, that is, in order to diverge toward the viewer, A so-called metal back structure, in which a light-reflecting metal thin film is formed by vapor deposition on a fluorescent film, is generally used.

The metal back fluorescent screen has the functions of increasing the brightness of the color picture tube and preventing the phenomenon of ion burning.

FIG. 3 is a schematic sectional view of such a color picture tube. In the color picture tube, a fluorescent film 2 is formed by coating on the inner surface of a glass face plate (hereinafter referred to as "panel") 1a which constitutes the front surface of the glass tube body 1. On the surface of the fluorescent film 2, an intermediate film 3 (see FIG. 4) made of a film racker material containing an organic material as a main component is formed in order to smooth the surface side. A reflective metal thin film 4 made of aluminum is deposited on the surface of the intermediate film 3 so as to cover the surface. The intermediate film 3 is thermally decomposed and removed in a later step.

In the color picture tube configured as described above, the electron beam emitted from the electron gun 7 passes through a large number of fine holes provided in the shadow mask 6 and enters the fluorescent film 2 corresponding to these holes, and The image appears. in this case,
The transmittance of the electron beam passing through the shadow mask 6 is 15 to
As low as 30%, the remaining 70 to 85% of the electron beam collides with the shadow mask 6, and the energy of the electron beam increases the temperature of the shadow mask 6, resulting in thermal expansion and deformation of the shadow mask 6, The light emitting position of the fluorescent film corresponding to the mask hole is displaced, resulting in a doming phenomenon. Along with this phenomenon, color misregistration, so-called mislanding, occurs, and the color image quality is significantly deteriorated.

Therefore, in order to reduce mislanding, a blackened aluminum thin film 5 which is a heat absorbing substance thin film is formed on the outer surface of the light reflecting metal thin film 4.

A conventional method for forming a blackened aluminum thin film of a color picture tube will be described with reference to FIG. The panel 1a on which the light-reflecting metal thin film 4 is deposited is airtightly supported on the holder 11 of the deposition envelope 8 via the packing 12. An evaporation source 9 formed by winding a tungsten wire in a coil shape is arranged inside the envelope 8 at a position spaced apart from the inner surface of the panel 1a. The tungsten wire forming the heating line of the evaporation source 9 is a stranded wire made of three or four tungsten wires (diameter: 0.5 to 0.8 mm) having a purity of 99.99%. An aluminum wire 10 having a diameter of 2 mm or 3 mm is placed in the evaporation source 9. The length of this aluminum wire 10 is the size of the panel 1a (inch size).
It is adjusted by.

Next, the inside of the envelope 8 is evacuated by an exhaust device (not shown).
While keeping the vacuum at 1 to 0.3 Torr, energize the evaporation source 9 for about 15 minutes.
The temperature is raised to 00 ° C. and the aluminum wire 10 is melt-deposited to form the blackened aluminum thin film 5.

After the blackened aluminum thin film 5 is formed in this manner, a baking treatment is performed at 420 to 430 ° C. to decompose and remove the intermediate film 3 made of the film lacquer material, thus completing the fluorescent screen formation.

After this, a color picture tube is completed through a step of sealing the panel 1a and the funnel 1b with solder glass and then a normal step.

FIG. 5 shows 9 parts of the evaporation source. The length l of the aluminum wire 10 put in the evaporation source 9 was not restricted with respect to the length L of the coiled portion 9a of the evaporation source 9.

[Problems to be Solved by the Invention]

In the conventional method of forming a blackened aluminum thin film for a color picture tube as described above, when the evaporation source 9 is electrically heated, the temperature of the portion A having the aluminum wire 10 rises slowly, and the temperature of the portion B having no aluminum wire 10 rapidly increases. The temperature rises to over 1500 ℃, and the difference is over 500 ℃. When the aluminum wire 10 begins to melt at the portion A due to heating, the molten aluminum at the boundary portion C between the portions A and B has a diameter of 0.
There was a problem that the molten particles of 1 to 0.5 mm were scattered on the light-reflective metal thin film 4 on the inner surface of the panel 1a, and the heat of fusion caused a defect of peeling the metal thin film 4.

The present invention has been made to solve such a problem, in the heating evaporation of an aluminum wire by an evaporation source, eliminates the scattering of molten particles of aluminum, prevents peeling of the light-reflecting metal thin film, An object of the present invention is to obtain a method for forming a blackened aluminum thin film of a color picture tube which improves the rate.

[Means for solving the problem]

In the method for forming a blackened aluminum thin film of a color picture tube according to the present invention, the length of the aluminum wire is regulated to 0.7 or less or 1.0 or more with respect to the length of the coiled portion of the evaporation source.

[Action]

In this invention, when the evaporation source is energized to generate heat, the ratio of the length of the aluminum wire in contact with the coiled portion is 0.7.
It is less than or equal to 1.0, and the entire coil part is heated almost uniformly, the local temperature difference is reduced, the aluminum wire is uniformly melted and evaporated in a spray form, and the blackened aluminum thin film is formed on the light reflective metal thin film. Is formed by vapor deposition, and molten aluminum particles are not scattered unlike the conventional case.

〔Example〕

FIG. 1 is a schematic sectional view of an apparatus part showing a method for forming a blackened aluminum thin film of a color picture tube according to an embodiment of the present invention. 1a, 2 to 5, 8, 9, 9, 11 and 12 are the same as those of the conventional apparatus. They are the same and will not be described. The electrode 14 connecting and supporting both ends of the evaporation source 9 is arranged 200 mm below the inner surface of the panel 1a. 13 aluminum wire 20 with a purity of 99.99% and a diameter of 2 mm
Cut into mm length, and insert this into the coil portion of the evaporation source 9.

This evaporation source 9 part is shown in FIG. The ratio of the length l of the aluminum wire 10 to the length L of the coiled portion 9a of the evaporation source 9 is regulated to 0.7 or less or 1.0 or more. The aluminum wire 10 is in contact with the coiled portion 9a at the portion A, but not at the portion B.

The ratio of the length of the aluminum wire 10 to the coil-shaped portion 9a is obtained from the experimental results shown in the following table.

In this experiment, as the evaporation source 9, three burnt wires of tungsten wire having a diameter of 0.5 mm were used, and the coiled portion 9a had an outer diameter of 6 mm,
The length L is 25 mm. In order to prevent the blackened aluminum thin film 5 from concentrating in the center of the inside of the panel 1a (that is, it is widely distributed), the coil-shaped portion 9a is formed as shown in FIG.
It is tilted 15 °.

The length l of the aluminum wire 10 was set to 0.52 with respect to the length L of the coiled portion 9a of the evaporation source 9 set as described above.

As shown in FIG. 1, after setting the vapor deposition envelope 8, the fluorescent film 2, the intermediate film 3, and the light-reflecting metal thin film 4 were formed.
Pack the inch panel 1a on the holder 11 of the envelope 8.
Support airtight through 12.

Next, the inside of the envelope 8 is removed by an exhaust device (not shown).
When the evaporation source 9 is energized while maintaining a vacuum of × 10 ^-2 Torr, the temperature of the coil upper portion 9a rises almost uniformly. About 1500
At the temperature of ℃, the aluminum wire 10 melts and evaporates,
It is vapor-deposited on the light reflective metal thin film 4 together with the blackened aluminum thin film 5.

After this, as usual, the panel 1a and the funnel 1b are sealed with a solder glass, and then the normal process is completed to complete a color picture tube.

In the above example, the length l / L of the aluminum wire 10
However, when l / L was set to 1.0, the temperature rise of the evaporation source 9 was further homogenized, and good results were obtained without scattering of aluminum molten particles. However, when l / L is 1.0 or more, aluminum wire
When the end portion of 10 protrudes from the end of the coiled portion 9a by 5 mm or more, when the aluminum wire 10 is melted, the protruding portion melts and falls because heat conduction is delayed, so that the protruding dimension is not preferably 5 mm or more.

If the panel 1a has the same size, the l / L relationship is
The length of the aluminum wire 10 is adapted to the dimensions of the panel 1a,
It is better to change the length of the coiled portion 9a of the evaporation source 9. This is because the thickness of the blackened aluminum thin film 5 changes when the length of the aluminum wire 10 is changed. If it is too thick, the brightness of the screen will be reduced, and if it is too thin, the doming effect will be halved.

Further, in the above-mentioned embodiment, the evaporation source 9 is arranged laterally, but the same effect can be obtained by the vertical arrangement.

Further, in the above embodiment, one end of the aluminum wire 10 is aligned with one end of the coil-shaped portion 9a of the evaporation source 9, but it is not necessary to align them.

〔The invention's effect〕

As described above, according to the present invention, the length of the aluminum wire is 0.7 or less or 1.0 with respect to the length of the coiled portion of the evaporation source.
Because of the above restrictions, it is possible to prevent the molten aluminum particles from scattering and peeling off from the light-reflecting metal thin film, which stabilizes the quality and significantly improves the non-defective rate.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an apparatus section showing a method for forming a blackened aluminum thin film of a color picture tube according to an embodiment of the present invention, FIG. 2 is an enlarged view of an evaporation source section of FIG. 1, and FIG. FIG. 4 is a schematic vertical sectional view of a picture tube, FIG. 4 is a vertical sectional view of an apparatus section showing a method for forming a blackened aluminum thin film of a conventional color picture tube, and FIG. 5 is an enlarged view of an evaporation source section in FIG. 1 ... Glass tube, 1a ... Glass face plate, 2
...... Fluorescent film, 3 ... Intermediate film, 4 ... Light-reflecting metal thin film,
5 ... Blackened aluminum thin film, 9 ... Evaporation source, 9a ... Coil-shaped portion, 20 ... Aluminum wire In the drawings, the same reference numerals indicate the same or corresponding portions.

Claims (1)

[Claims] 1. A step of forming a fluorescent film on the inner surface of a glass face plate, forming an intermediate film on the fluorescent film to form a smooth surface, and forming a light-reflecting metal thin film on the intermediate film, and then forming an evaporation source. An aluminum wire is placed in a coiled portion formed by a heating wire, the aluminum wire is melted and evaporated, and a blackened aluminum thin film is formed on the light-reflecting metal thin film by vacuum deposition. On the other hand, a method of forming a blackened aluminum thin film for a color picture tube, wherein the length ratio of the aluminum wire is regulated to 0.7 or less or 1.0 or more.