JPS6250939B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a phosphor screen for a color picture tube, and more particularly to a method for depositing a phosphor layer having a dense and uniform thickness on the inner surface of the face plate of a color picture tube. It is something.

The image characteristics of a color picture tube, namely clarity, brightness,
Contrast is largely influenced by the method used to form the dot-shaped or band-shaped phosphor layer that emits red, green, and blue colors when an electron beam hits the inner surface of the face plate of a color picture tube. and
There is a strong demand for a phosphor screen in which dense, high-brightness, uniform, smooth, and even phosphor layers are regularly arranged. Furthermore, the manufacturing of phosphor screens as mentioned above requires various manufacturing equipment used in the manufacturing process, and maintaining these various manufacturing equipment costs a huge amount of money, and improvements are desired. .

Next, a method for forming a phosphor screen on the inner surface of the face plate of a color picture tube and its drawbacks will be described.

The first method is the slurry method, in which, as shown in Figure 1, a phosphor slurry in which phosphor particles are dispersed in a photosensitive resin solution is added to the inner surface of the face plate, and then rotated at a high speed of several hundred times per minute. The first phosphor layer is formed by applying a phosphor slurry, drying it, exposing it to light through a shadow mask with many holes, and developing it to remove the unexposed areas. For example, a dot-shaped or band-shaped phosphor layer that emits blue light is formed. This process is sequentially applied to phosphors that emit green and red light, and a phosphor screen made of phosphor layers that emit light in three colors is finally completed. However, with this slurry method, it is extremely difficult to stably create a uniform film thickness on the inner surface of the face plate, and because of the high speed rotation, surrounding air and dust contained therein are mixed into the phosphor slurry. This not only causes defects in the phosphor layer, but also makes the manufacturing equipment complicated, expensive, and short-lived. Another drawback is that a considerable heat source is required to dry the coated film of the phosphor slurry, which increases the cost of maintaining air conditioning in the phosphor screen manufacturing room.

The second method is the dust method, in which only a photosensitive resin solution is first applied to the inner surface of the face plate of the color picture tube, and when the solution is semi-dry, powdered phosphor is attached. This is a method in which a phosphor film is formed, and then, like the slurry method, a phosphor layer is formed by drying, exposing, and phenomenon, but this method not only requires high-speed rotation to apply the photosensitive resin solution, but also It is difficult to apply the phosphor uniformly,
It has the same drawbacks as the first slurry method.

The present invention has been made in view of the above-mentioned conventional drawbacks, and is directed to the manufacture of a phosphor screen for a color picture tube, in which a phosphor screen consisting of three color phosphor layers of red, green, and blue is formed on the inner surface of the face plate by an electrodeposition method. The purpose is to provide a method.

The electrodeposition method used in the manufacturing method of the present invention utilizes the principle of electrophoresis, and the method for forming a phosphor screen using this method uses a special electron tube, such as an output phosphor for an image intensifier (II). In these cases, a phosphor layer that emits light in a single color is formed on the desired surface. This is completely different from a manufacturing method in which a photosensitive resin solution is used to form the body layers only at predetermined positions, and exposure and development are performed.

Next, a first embodiment of the present invention will be described.

As shown in Fig. 3, first an inorganic transparent conductive film, such as indium oxide or tin oxide nesa film, or an organic conductive film is deposited on the inner surface of the face plate, and then this is used as one electrode to conduct the inorganic transparent conductive film. A metal placed opposite the film or an organic conductive film (hereinafter simply referred to as a conductive film) is immersed as the other electrode in an electrodeposition solution containing essentially a desired phosphor and a negative resist. A phosphor and a negative resist are simultaneously deposited on the conductive film by connecting a DC power source between the voltages. Needless to say, the film formed in this way, consisting of the phosphor and negative resist, is dense and has a uniform thickness, and can be formed by simply immersing it in the electrodeposition solution for several seconds to several minutes and applying electricity. Not only does it not require high-speed rotation of the face plate as in the conventional method, but the amount of water adhering to it is also extremely small, so the amount of heat required for drying can be reduced, and the manufacturing equipment and maintenance costs are reduced to just a few minutes compared to the conventional method. There is an effect that only 1 is required.

Next, after drying the phosphor layer made of the phosphor and negative resist formed on the face plate, it is exposed to light through a shadow mask having a large number of through holes, and then the unexposed areas are developed. A first color phosphor layer is obtained. The next second and third color phosphor layers are also formed using other phosphors by repeating the steps after the step of immersing the phosphor and negative resist in the electrodeposition solution described above and energizing them. I can do it. In the case of an organic conductive film, a phosphor screen may be formed, and the organic conductive film may be incinerated after forming a metal bag.

Next, a specific example of this first embodiment will be explained based on FIG. 4. First, a NESA film 2 of indium oxide was formed on the inner surface of the face plate 1 by a vapor deposition method, and then the NESA film 2 of the face plate 1 was placed opposite to another electrode 3 and immersed in an electrodeposition liquid 4, and energized.

The electrodeposition solution 4 used was one consisting of 1 medium CH ₃ OH and 2 phosphor dispersions and a powder concentration of 100 g/3. Here, the phosphor dispersion liquid is phosphor
Pure water was added to 100 g + 5 g of polyvinyl alcohol + 0.2 g of ammonium dichromate to make 2, and this was ball milled for 3 hours with 3 kg of 5 mm diameter glass balls.

In this case, between the Nesa membrane 2 and the electrode 3
By applying 50 VDC, it was possible to form an electrodeposited layer 5 of 20 μm on the Nesa film 2 in an electrodeposition time of 15 seconds.

Next, it was dried and exposed through a shadow mask using an exposure device to expose the resist at desired positions, and then the unexposed portions of the resist were developed with water to form a first color phosphor layer.

Further, the process from electrodeposition to development was adapted to the second color phosphor and the third color phosphor to produce a phosphor screen consisting of three color phosphor layers.

As a result of manufacturing a color picture tube by applying a face plate with such a phosphor screen to a normal color picture tube manufacturing process, the brightness was improved by 10% compared to the one using the conventional slurry method, and the film uniformity was improved. In other words, we were able to reduce the deviation in white balance to about 1/3 and obtain a color picture tube with significantly improved performance.

In the above specific example, polyvinyl alcohol and ammonium dichromate were used as resists, but
This can also be applied to resists made of polyvinyl pyrrolidone and diazidostilbene-based sensitizers, as well as resists made of polyvinyl alcohol and cinnamic acid esters, by selecting appropriate electrodeposition conditions. Of course, a small amount of surfactant may also be used to improve the dispersibility of the phosphor.

Next, a second embodiment of the present invention will be described.

As shown in Figure 5, first a conductive film is formed on the inner surface of the face plate, and then a solution consisting of 100 g of ethyl alcohol + 2 g of Mg(NO ₃ ) ₂ + 300 g of phosphor is used as an electrodeposition solution, and 50 VDC is applied between the electrodes and the other electrodes. was applied for 3 seconds to electrodeposit the phosphor on the conductive film.
Add pure water to 5g of polyvinyl alcohol and 0.2g of ammonium dichromate to make a 5% aqueous solution.A resist is applied by immersion in this solution or by electrodeposition, followed by drying, exposure, and development. A first color phosphor layer was formed on the inner surface of the face plate. Furthermore, the steps after electrodeposition of the phosphor were repeated for the second color and the second color phosphor to complete the phosphor screen. Since this method separates the deposition of only the phosphor and the deposition of the resist, it is possible to further densify the phosphor layer and make the thickness of the film uniform.

Next, a third embodiment of the present invention will be described.
This embodiment is particularly an example of application to a beam index type color picture tube, and in this case, the phosphor screen consisting of three color phosphor layers may be formed by a conventional slurry method or the like. It may be formed by a method of attachment. After the formation of this phosphor screen, lacquer filming is usually performed, and a metal back layer of aluminum or the like is formed to further increase the brightness. Alternatively, a phosphor layer for index detection can be made uniform and sharp by immersing it in an electrodeposition solution containing a secondary electron emitting substance (referred to as a phosphor in the present invention) and applying a direct current between it and other electrodes. (phosphor screen) or a secondary electron emitting material layer (phosphor screen) could be formed.

It should be noted that the above-described embodiments illustrate the principle manufacturing method of the present invention, and it goes without saying that various modifications can be made within the scope of the claims.
Its industrial value is extremely large.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a method for forming a fluorescent screen on the inner surface of a face plate using the conventional slurry method.
Figure 2 is a block diagram of a method for forming a fluorescent screen on the inner surface of a face plate using the conventional dust method.
The figure is a block diagram of the first embodiment of the present invention, FIG. 4 is a sectional view showing the electrodeposition method, and FIG. 5 is a block diagram of the second embodiment. 1... Face plate, 2... Conductive coating, 3
. . . other electrodes, 4 . . . electrodeposition liquid, 5 . . . electrodeposition layer.

Claims (1)

[Claims] 1. A step of forming a conductive film on the inner surface of the face plate of a color picture tube directly or via a phosphor screen;
The conductive film is used as one electrode, and an electrodeposition solution containing substantially a resist and a phosphor or an electrodeposition solution containing only a phosphor is interposed between the electrodes opposite to this electrode. A mixed film of phosphor and resist or a film of only phosphor is formed on the conductive film by applying a DC voltage between the electrodes provided, and further, in the case of a film of only phosphor, a resist film is formed on this. 1. A method for manufacturing a phosphor screen for a color picture tube, comprising the steps of: drying, exposing and developing a phosphor layer of a predetermined shape. 2. The method of manufacturing a phosphor screen for a color picture tube according to claim 1, wherein the conductive film is an inorganic transparent conductive film formed directly on the inner surface of the face plate. 3. The method of manufacturing a phosphor screen for a color picture tube according to claim 1, wherein the conductive film is an organic conductive film formed directly on the inner surface of the face plate. 4. A method for manufacturing a phosphor screen for a color picture tube according to claim 1, wherein the conductive film is a metal back layer formed on a phosphor film. 5. A method for manufacturing a phosphor screen for a color picture tube according to claim 1, wherein the phosphor layers are each made of a different phosphor. 6. The method for manufacturing a phosphor screen of a color picture tube according to claim 1, wherein the phosphor layer is a phosphor for index detection or a secondary electron emitting material for index detection.