JPH0550089B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a so-called transfer fluorescent film forming method for forming a fluorescent film surface of a cathode ray tube (CRT) by transfer.

[Conventional technology]

Hereinafter, a cathode ray tube will be referred to as a CRT. A method for forming a phosphor film on a CRT using a flat tube with a curvature on the phosphor screen is the transfer method, in which a phosphor layer is printed in advance on a flat substrate that is easy to print, and then transferred to a flat panel. There is. Transfer methods include water transfer methods, heat transfer methods, and the like. These two methods will be explained here. FIG. 4 shows the state in which each component has been applied when performing the water transfer method.
Here, FIG. 4 is a sectional view showing a state in which the substrate 4, the water release layer 6, the coating film 5, and the cover coat film 7 are formed. First, a water-soluble substance is applied onto the substrate 4 to form a water-release layer 6. On top of this, a fluorescent paste made of ink with fluorescent material and resin is applied by screen printing to form a coating film 5. Furthermore, resin is printed on top of this using the same screen printing method,
A cover coat film 7 is formed. Next, add this to board 4
If the substrate is immersed in water, the water release layer 6 will dissolve in water, and the coating film 5 and cover coat film 7 will be peeled off from the substrate 4. Transfer is performed by pasting the peeled coating film 5 and cover coat film 7 onto a flat panel with the cover coat film surface 7 facing upward and drying.
FIG. 5 shows the state in which each component has been applied when performing a thermal transfer method. Here, FIG. 5 shows the substrate 4,
FIG. 3 is a cross-sectional view showing a state in which a thermal release layer 8, a coating film 5, and a thermal adhesive film 9 are formed. First, a thermally peelable layer 8 is provided by coating the substrate 4 with a substance that melts when heated at a low temperature. On top of this, a fluorescent paste made of ink with fluorescent material and resin is applied by screen printing to form a coating film 5. Furthermore, a thermal adhesive film 9 which becomes sticky at a certain temperature or higher is formed thereon by the same screen printing method. Next, the substrate 4 is heated at a low temperature to melt the thermal release layer 8, and the coating film 5 and the thermal adhesive film 9 are peeled off from the substrate 4. Transfer is performed by pasting the peeled coating film 5 and thermal adhesive film 9 onto a flat panel with the thermal adhesive film surface 9 facing down and drying.

[Problem to be solved by the invention]

When a coating film of phosphor is provided on a substrate by screen printing, the surface of the coating film in contact with the substrate becomes the same smooth surface as the substrate. On the other hand, the surface of the coated film that is not in contact with the substrate will not have a smooth surface because of the mesh marks left by the screen. For this reason, leveling is usually performed after screen printing is completed in an attempt to obtain a smooth surface, but it is difficult to achieve the same level as the surface in contact with the substrate. When displaying an image on a fluorescent display screen, thicker parts of the fluorescent film have lower brightness, and conversely, thinner parts of the fluorescent film have higher brightness. Therefore, if the phosphor film is not smooth, uneven brightness will occur and the quality of the phosphor display screen will deteriorate. Further, in that case, the smoothness of the phosphor screen on the side where the image is viewed greatly affects the brightness unevenness. In the conventional method of forming a fluorescent film using water transfer, when the transfer is completed, the surface on the substrate side remains in contact with the panel surface. Therefore, the smoothness of the surface not in contact with the panel is poor, which deteriorates the quality of the reflective fluorescent display screen observed from the side where the electron beam is incident. In the conventional method of forming a fluorescent film using thermal transfer, when the transfer is completed, the surface opposite to the substrate comes into contact with the panel. For this reason, the smoothness of the panel side is poor, which deteriorates the quality of the transmission type fluorescent display screen observed from the panel side. In addition, a problem with these water transfer methods and thermal transfer methods is that they require many work steps.
In the water transfer method, it is necessary to form a water release layer and a cover coat film in addition to the coating film actually used. In the thermal transfer method, it is necessary to form a thermal release layer and a thermal adhesive film in addition to the coating film actually used. As described above, the conventional method has poor productivity due to the large number of steps.

[Means to solve the problem]

In the method of forming a CRT fluorescent film, only a fluorescent paint composed of a fluorescent material and a resin material is applied onto a substrate to form a coating film. This coated film is peeled off in water and then attached to a panel to form a fluorescent film.

〔Example〕

FIG. 1 is a schematic view showing the state of an intermediate procedure of the present invention, and shows a glass plate 1 and a coating film 5 of phosphor. A fluorescent paint composed of phosphor and resin material was applied onto a clean, flat glass plate measuring 30 mm x 30 mm by screen printing using a 300-mesh stainless steel screen. At this time, the phosphor was P45, which is used for black and white televisions.
was used. The resin material is a variety of resin from Mitsubishi Rayon Co., Ltd.'s Dianal BR resin.
A mixture of BR90, BR101, BR112, and BR118 was used. After printing, leveling was performed for 24 hours to obtain a somewhat smooth coating film. Next, it was dried at 200° C., a temperature at which the resin material does not evaporate. If the temperature applied to the coated film during drying is uneven, the thickness of the coated film will vary, so the heating was done uniformly. Subsequently, this glass plate was immersed in pure water, and after 1 hour, the glass plate and the coating film were peeled off in water. A cross-sectional view of FIG. 2 shows a state in which a portion of the coating film has been peeled off. Here, 1 is a glass plate and 5 is a coating film. At this time, the time required for peeling can be shortened by applying ultrasonic impact or heating water. FIG. 3 is a cross-sectional view of the state in which the transfer is completed according to the present invention, showing the panel 2 and the fluorescent film 3. The peeled coating film was attached to a panel to be used as a transmission type fluorescent display screen, with the surface in contact with the substrate facing the panel. This was fired at 400°C and the resin was purged to form a phosphor film made of pure phosphor. According to this example, the coating film could be peeled off from the glass plate by immersion in water without providing a water release layer, and it could be attached to a panel without providing an adhesive layer.

〔Effect of the invention〕

In addition to being able to form a fluorescent film using the transfer method in fewer steps, the surface on which the coating film is attached can be changed, making it possible to create fluorescent display surfaces that are less likely to exhibit brightness unevenness for both transmissive and reflective fluorescent display screens. Obtainable.

[Brief explanation of drawings]

FIG. 1 is a schematic view showing an intermediate step of the present invention, in which a phosphor coating film is formed on a flat glass plate. FIG. 2 is a schematic diagram showing an intermediate step of the present invention, with the phosphor coating film partially peeled off from the glass plate. FIG. 3 is a cross-sectional view showing a state in which transfer is completed according to the present invention, and a fluorescent film is formed on the panel. FIG. 4 is a sectional view showing a state in which each component has been applied in the water transfer method. FIG. 5 is a sectional view showing a state in which each component has been applied in the thermal transfer method. DESCRIPTION OF SYMBOLS 1... Glass plate, 2... Panel, 3... Fluorescent film, 4... Substrate, 5... Coating film, 6... Water release layer, 7... Cover coat film, 8... Thermal release layer, 9
...Thermal adhesive layer.

Claims (1)

[Claims] 1. In a method for forming a transferred fluorescent film on a cathode ray tube having a panel, a funnel, and an electron gun, a fluorescent paint composed of a fluorescent material and a resin material is applied onto a substrate to form a coating film of the fluorescent material, and then the film is placed in water. A transfer fluorescent film forming method characterized by peeling off this coating film and pasting it on a panel.