JPS6145341B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a picture tube for color television, and more particularly to a method of manufacturing a picture tube in which both a light-absorbing film pattern and a fluorescent film pattern are formed on a glass plate. In general, color television picture tubes have been conventionally manufactured using photolithography, a so-called exposure method. This method is characterized by being able to reduce the amount of resin (binder) contained in the fluorescent film pattern or light absorption film pattern, and therefore reduces the amount of decomposition generated from the resin in the firing process after forming the metal back film in the subsequent process. It is possible to hold down less gas. However, as is well known, picture tubes for color televisions require three colors of phosphor film: red, green, and blue, and in order to apply these three color phosphor films, alignment is required each time. This was complicated as it required masking and exposure and development three times. This conventional method is a wet method, and has the drawbacks of difficult process control and poor product yield. In contrast, the present inventors have previously proposed applying a fluorescent film pattern by a printing method instead of the conventional exposure method. According to this printing method, it is sufficient to print ink containing a large amount of phosphor onto a glass plate using a prepared printing plate, so that the process is extremely simplified. However, printing laws are not without problems. In other words, since it is a printing method, ink is used, but the amount of resin (vehicle) contained in this ink is much higher than that of the fluorescent film obtained by the exposure method, and this large amount of resin will cause problems later. This is a disadvantage in that the metal back layer may blister or tear during the firing process. The present invention is a method for manufacturing a color television picture tube that overcomes the drawbacks of the printing method as described above. The present invention will be specifically explained below. That is, the present invention
This method selectively creates breathable pinholes in the metal back layer on the light-absorbing film pattern, which does not directly affect the light-emitting characteristics and brightness characteristics of the picture tube. Its purpose is to release decomposed gas generated from the resin contained within the optical film. Specifically, it is a color television picture tube in which a light-absorbing film pattern is formed on a glass plate, and a three-color fluorescent film pattern of red, green, and blue is formed by a printing method on the exposed part of the glass plate. The light-absorbing film pattern is structured so that the amount of decomposed gas generated from the resin during heating is larger than that of the fluorescent film pattern, and in the baking process after applying the metal back layer, the light-absorbing film pattern is It is characterized by selectively creating a large number of breathable pinholes in the metal back layer covering the body. This will be explained in more detail below. FIG. 1 is a partially enlarged sectional view showing an example of a picture tube for a color television according to the present invention. Three colored fluorescent film patterns 3 of red, green and blue are printed in this arrangement order on the parts of the plate 1 where the light absorption film pattern 2 is not applied. A metal back layer 4 is formed by depositing a metal such as aluminum so as to cover it. Defects such as blisters and pinholes that occur in the metal back layer 4 are caused by gas generated by thermal decomposition or oxidative decomposition of resin components during the firing process. Experiments have shown that if there are no pinholes in the metal back layer 4, it will bulge and be useless, but if there are many pinholes, no bulge will occur, but the reflectance of the metal back layer 4 will decrease, resulting in a significant drop in brightness characteristics. This also results in deterioration of the fluorescent surface. Therefore, a moderate pinhole density will give the best results. One way to prevent blistering is to control the gas generated. If the amount of gas generated during the firing process is small, the gas will be released from the minute pinholes present in the metal back layer 4, and no blistering will occur. In order to reduce the amount of gas generated, the amount of resin may be reduced. However, if the amount of pigment is increased and the amount of resin is decreased, the suitability for patterning such as printing becomes poor, so there is a limit to controlling blisters using only the amount of resin. The next measure to prevent blistering is to control the thickness of the metal back layer 4. If the metal back layer 4, such as aluminum, is thin, there will be many pinholes,
The generated gas escapes easily and does not cause blisters. However, as described above, if there are many pinholes, the brightness characteristics will deteriorate, making the surface unsatisfactory as a fluorescent surface. "Tear" in the metal back layer caused by pinholes in the metal back layer 4 and blistering during the firing process must not be larger than the line width of the fluorescent film pattern 3, and even more so, must not extend over the light absorbing film pattern 2. Large defects make it unsuitable for use as a picture tube. Furthermore, if the metal back layer 4 is thick, defects due to bulges will increase, and
The rate at which the electron beam reaches the phosphor also decreases, resulting in poor brightness. Taking all these into account, it was found that the practical thickness of the metal back layer 4 is 600 to 2500 Å. In the printing method, there is a limit to how low the resin content can be, and other factors must be controlled to obtain a stable fluorescent surface. In order to maintain patternability and prevent pinholes and blisters, it is also quite effective to perform preheating before forming the metal back layer 4. That is,
In this method, a part of the gas generated during the firing process is dissipated by preheating before forming the metal back layer 4, thereby reducing the amount of gas generated during the firing process. When the amount of gas generated is small, the gas scatters through tiny pinholes and does not cause blisters or tears. However, if the preheating temperature is high, the adhesiveness with the face plate will decrease, and there is a risk that the pattern will peel off in a subsequent process. Particularly, when a phosphor pattern for index signal detection (index pattern 5) is formed on the metal back layer 4 using the index method, the underlying metal back layer 4, phosphor film pattern 3, and light absorption film pattern 2 are destroyed. This occurs regardless of whether the index pattern 5 is formed using an exposure method or a printing method, but the pattern is more likely to collapse in the printing method because printing pressure is applied to the metal back surface. From these facts, the effective temperature range for preheating can be determined. Effective preheating conditions vary depending on the resin, for example, 170 to 290°C for acrylic resin and 170 to 400°C for polyester resin. Furthermore, it goes without saying that the preheating conditions are not uniquely determined by the temperature alone, but vary depending on the time and the atmosphere of the preheating furnace. It is clear that a high quality fluorescent surface can be obtained by selecting appropriate preheating conditions. The integrity of the phosphor film is necessary to obtain the necessary brightness and generation characteristics. However, some defects can be tolerated in the light-absorbing film portion. For example, pinholes in the metal back layer 4 above the pattern of the fluorescent film reduce the brightness characteristics, but pinholes in the light absorbing film hardly affect the characteristics of the fluorescent surface. Therefore, by concentrating defects on the light-absorbing film and ensuring the integrity of the fluorescent surface, the characteristics of the fluorescent surface will be satisfied. In order to make the defect densities different between the fluorescent film and the light absorption film, it is sufficient to obtain different gas generation amounts or gas generation conditions between the fluorescent film and the light absorption film. Gas evolution depends on the type of resin and resin content. Therefore, an appropriate means is to change the resin compositions (components and ratios) of the fluorescent film and the light-absorbing film. One specific method is that when using the same resin, in the unfired state, if the weight of the resin contained in the fluorescent film is 1%, the weight of the resin in the light absorption film is 1.5%.
It is to be set to ~3.5x. In this way, the amount of decomposed gas generated from the light-absorbing film increases, creating many pinholes in the metal back film on the light-absorbing film pattern, and through these pinholes, the decomposed gas generated from the fluorescent film pattern is also transferred to the outside. flee to The resin content contained in the light-absorbing film and the fluorescent film can be adjusted by adjusting the resin (vehicle) content in the ink when preparing the printing ink. In addition to the above means, the amount of gas generated can be changed by selecting different resins. Naturally, a resin that generates a large amount of decomposed gas during firing is selected for the light-absorbing film. The table below shows the appropriate resins for each membrane pattern.

[Table] In the table above, all of the resins used for the fluorescent film pattern can be used as a vehicle for printing ink. Examples include using an ultraviolet curable polyester resin for the light film and using an acrylic resin or a photosensitive acrylic urethane resin for the light absorption film. When each of the above combinations is patterned and a metal back film is vapor-deposited and then baked, the metal back film has minute defects in the light absorption film part, but no defects in the fluorescent film part, and the brightness characteristics are improved.
The luminescent properties are as expected, and a good fluorescent surface is obtained. Due to the difference in the composition of the fluorescent film and the light absorption film, that is, the difference in the ratio of resin or the difference in the resin itself,
Although the integrity of the fluorescent surface is obtained after the firing step, it is of course possible to control both the resin itself and its proportions in combination. In addition, in an index type color television picture tube, as shown in FIG. 1, an index pattern 5 is provided on the metal back layer 4 at the same pitch as the light absorption film pattern 2. If this index pattern 5 is misaligned after firing, it will not function properly as a fluorescent surface, but defects in the metal back layer 4 that occur in the light absorber portion of the fluorescent surface manufactured by the method described above are not a problem. It won't happen. As described above, by changing the composition of the resin in the fluorescent film pattern and the light-absorbing film pattern, the present invention intentionally eliminates many pinhole defects only in the metal back layer covering the light-absorbing film pattern. By doing this, the decomposition gas generated from the resin of the fluorescent film pattern is also reduced.
It escapes through pinhole defects in this metal back layer. In the present invention, although some defects occur in the light-absorbing film portion, the integrity of the fluorescent film portion is maintained, and a fluorescent surface with excellent brightness and light-emitting properties can be obtained. Examples will be described below. Example 1 A graphite pattern, which is a light-absorbing film, and then red, blue, and green phosphor patterns were formed on a face plate, and an aluminum bag was evaporated, a baking process was performed, and an ultraviolet index pattern was manufactured. It has a structure like this. All patterns were created using the gravure offset printing method. The composition of the ink for the light-absorbing film is as follows.

[Table] The fluorescent film pattern was formed using ink with the following composition. The pigment is red phosphor - Dainippon Paint P-22RE3,
Blue phosphor - Dainippon Paint P22-B1, green phosphor -
Dainippon Paint P22-GN4 was used, and the pigment ratio was the same for each color.

[Table] Printability was good in all cases. After printing, the fluorescent ink was dried by irradiation with ultraviolet light. Aluminum was deposited to a thickness of 1500 Å on the fluorescent surface to form a metal back film, and then fired. Firing was continued for 30 minutes at a maximum temperature of 430°C. Before firing, there were no apparent pinholes in the metal back film, but after firing, some defects appeared in the light absorber. The fluorescent surface satisfied the brightness generation characteristics. Further, after the metal back film was deposited, an index pattern was printed on the metal back film corresponding to the light absorption film pattern. The printing ink used had the same composition as the fluorescent ink except that the pigment was cesium fluoride. When the firing conditions were the same as above, a fluorescent surface satisfying the same characteristics was obtained. No increase or decrease in defects was observed due to the formation of the index pattern. Example 2 A fluorescent surface was produced in the same manner as in Example 1, except that the following light-absorbing substance ink was used.

[Table] Regardless of the presence or absence of an index pattern, a fluorescent surface with good characteristics could be obtained. The reason why it was possible to obtain good properties even when using the same resin is because the proportions of the resins in the fluorescent ink and the graphite ink are different, and the amount of gas generated during firing is different. Example 3 Acrylic resin was selected as the resin for both the light absorber ink and the fluorescent ink, and the compositions of the inks were as follows. Light-absorbing film ink {graphite/acrylic resin = 1/3 (weight ratio) Fluorescent ink {fluorescent material (red, blue, green)/acrylic resin = 5/2 (weight ratio) In addition, a solvent is added, Patterns of each color of graphite phosphor were formed in order by screen printing. Aluminum vapor deposited film as metal back layer
Deposit on 1000Å pattern and bake at 430℃
I went for 30min. The integrity of the fluorescent surface was maintained, and good light emission and brightness characteristics were obtained. Further, even after the index pattern was formed on the metal back layer and baked, the phosphor surface was maintained, and no increase in defects occurred due to the formation of the index pattern. Example 4 The following photosensitive material was used to form a light absorber pattern by an exposure method. Graphite/photosensitive acrylic urethane resin (Kansai Paint Sonne) = 5/1 (weight ratio) It was applied to a thickness of 5 μm on a face plate, air-dried, a light absorber pattern master plate was placed on it, and it was irradiated with ultraviolet light.
Weakly alkaline solution (0.2% NaOH) heated to 35°C
When immersed in an aqueous solution, the unirradiated areas were dissolved and a light absorber pattern was formed. After drying, each color was sequentially printed using the phosphor ink used in Example 1 by screen printing. After depositing an aluminum film of 1500 Å as a metal back, it was fired at 450°C for 30 minutes. The integrity of the phosphor pattern was maintained, and good light emission and brightness characteristics could be obtained. Similar good results were obtained even when the index pattern was formed on the aluminum film and then baked.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view showing an embodiment of a color television picture tube obtained by the manufacturing method of the present invention. 1... Glass plate, 2... Light absorbing film pattern, 3... Fluorescent film pattern, 4... Metal back layer, 5... Index pattern.

Claims (1)

[Claims] 1. A method for manufacturing a picture tube for a color television, in which a light-absorbing film pattern is formed on a glass plate, and a three-color fluorescent film pattern of red, green, and blue is formed on the exposed surface of the glass plate, in which the light-absorbing pattern is The fluorescent film pattern is formed by a printing method using a printing ink whose vehicle is a type of resin selected from rosin-modified phenolic resin, acrylic resin, acrylic urethane resin, and photosensitive acrylic urethane resin, and the fluorescent film pattern is formed using acrylic resin, polyester resin, etc. It is formed by a printing method using a printing ink whose vehicle is a resin selected from resin, ultraviolet curable polyester resin, and vinyl chloride-vinyl acetate copolymer, and the light-absorbing film pattern contains a resin component generated during heating. The structure is structured so that the amount of decomposed gas generated is larger than that of the fluorescent film pattern, and preheating is performed to dissipate a part of the amount of gas generated in the firing process before forming the metal back film, and then the metal back film is formed. A method for producing a picture tube for a color television, characterized in that a large number of air-permeable pinholes are selectively generated in portions of a metal back layer covering a light-absorbing film pattern in a firing process after the layer is applied.