JPS5932854B2 - Cathode ray tube video screen formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a video screen on the inner surface of the face panel of a cathode ray tube, particularly an index color picture tube.

Generally, the video screen of a cathode ray tube consists of two steps: forming a phosphor film on the inner surface of the face panel, depositing a protective film made of an organic material on the inner surface of the phosphor film (on the electron gun side), and then forming a protective film on the inner surface of the phosphor film (on the electron gun side). It is manufactured by forming a thin metal film made of aluminum or the like on the inner surface of a protective film by vapor deposition, and gasifying the protective film by heating to eliminate it.

Polymethacrylate is usually used as the protective film, and as a pretreatment for forming the polymethacrylate film, a thin film of polyvinyl alcohol is formed.

To explain this with drawings, in FIG. 1 showing an example of forming a video screen in an index type color picture tube, a light absorbing film 2 made of graphite formed on the inner surface of a face panel 1 made of glass, and a green,
Three types of phosphor strips that emit blue and red light 3G, 3B, 3
R forms a so-called black matrix type phosphor film.

The protective film covering this phosphor film is made up of a thin film 4 of polyvinyl alcohol and a thin film 5 of an organic material such as polymethacrylate adhered to the inner surface of the film. A metal thin film 6 consisting of the above is formed by vapor deposition, and the inner surface of the metal thin film 6 is provided with phosphor strips 7 for generating an index signal.

Incidentally, the index signal generating phosphor strips 7 mainly generate ultraviolet light when stimulated by an electron beam.

The organic substance thin films 4 and 5 are gasified and disappear by heat treatment set after the formation of the index signal generating phosphor film 7, but the phosphor strips 3G, 3B, 3R
Because it is formed in contact with the surface of the phosphor particles that form the
Irregularities and pinholes 8 as shown in FIG. 2 are likely to occur.

The pinholes 8 do not allow a portion of the metal thin film 6, which is then formed by vapor deposition, to penetrate between the phosphor particles, but instead create defects in the metal thin film, which significantly deteriorates the light emitting characteristics of the phosphor film.

Furthermore, when forming the index signal generating phosphor strips 7 on the inner surface of the metal thin film 6 in an index-type color picture tube, this phosphor slurry penetrates into the underlying phosphor film through the defects and pinholes 8. , causing stains, unevenness or fogging, leading to unfavorable results.

Conventionally, as a means to prevent the permeation, the organic thin films 4 and 5 before forming the metal thin film are heated to a temperature of 70° C. to 90° C. to be cured. In fact, it may cause unevenness in the protective film and deteriorate the light emitting characteristics.

The present invention has been made in view of the above-mentioned points, and according to the method of forming a video screen for a cathode ray tube according to the present invention, an organic protective film is formed on the inner surface of a phosphor film, and then a metal thin film is formed by vapor deposition. First, a metal thin film is formed to a thickness corresponding to a part, for example, approximately half, of the film thickness required for a so-called metal back.

Then, an organic solvent such as toluene is applied to the inner surface, and after drying, a metal thin film is formed again.

As a result, the thickness of the metal thin film reaches the required thickness, and on the other hand, the organic solvent acts on a part of the protective film and dissolves it, so that the pinhole disappears.

Next, the present invention will be explained in more detail with reference to the drawings. In FIG. 3, for example, blue light emitting phosphor strips 3B as a phosphor film formed on the inner surface of the face panel 1 made of glass are made of polyvinyl alcohol. It is first covered by a thin film 4, which has a thin film 5 of polymethacrylate or other organic material deposited on its inner surface.
It also forms a protective film.

A metal thin film 9 made of aluminum is formed by vapor deposition on the inner surface of this protective film, and the thickness of this metal thin film 9 is approximately half the thickness required for the metal back. The metal thin film molecules that have entered through the pinhole 8 in the film are attached to the surface of the phosphor particles.

At this manufacturing stage, when toluene or other organic solvent is applied, this organic solvent dissolves a portion of the protective film, and after 3 to several seconds, a protective film 5 formed by the dissolved organic material is formed, as shown in FIG. ' completely fills the pinhole.

Therefore, when the organic solvent is dried and a metal thin film made of aluminum is again formed by vapor deposition, a metal thin film 10 as a second layer is formed as shown in FIG.
The metal thin films 9 and 10 form a substantially single metal back having the required thickness and having no pinholes.

In the production of index-type color picture tubes, phosphor strips for index signal generation are then formed,
The protective film is then heated to disappear.

As described above, the method for forming a video screen for a cathode ray tube according to the present invention involves forming a protective film made of an organic material on the inner surface of a phosphor film deposited on the inner surface of a face panel, and then forming a protective film made of an organic material as a metal back. When forming a thin film by vapor deposition, the metal thin film is divided into a first stage and a second stage to form a plurality of layers, and a stage of applying an organic solvent is provided between the first and second stages. Therefore, it is possible to form a metal back having no pinholes, and particularly when applied to the manufacture of color picture tubes, especially index-type color picture tubes, very excellent effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional index-type color picture tube video screen, FIG. 2 is a more enlarged side sectional view of the same video screen, and FIGS. 3 to 5 are formed by the method of the present invention. FIG. 3 is a side sectional view showing the video screen in the order of manufacturing steps. 1...Face panel, 3G, 3B, 3R...
...phosphor strips, 4,5... thin film of organic substance, 6,9°10... thin film of metal.

Claims (1)

[Claims] 1. When forming a protective film made of an organic substance on the inner surface of the phosphor film deposited on the inner surface of the face panel, and then forming a metal thin film as a metal back by vapor deposition, the metal thin film is subjected to a first step. 1. A method for forming a video screen for a cathode ray tube, comprising: forming a plurality of layers into a plurality of layers, and a step of applying an organic solvent between the first and second steps.