JPS6110935B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a phosphor surface of a color picture tube, and more particularly to a method for applying a phosphor slurry therefor.

Generally, the fluorescent surface of a color picture tube has three types of fluorescent films that emit red, blue, and green light, arranged regularly in a matrix or stripe pattern on the inner surface of the panel. To obtain such a fluorescent surface, for each fluorescent film, a phosphor slurry to which a photosensitive binder has been added is applied to the inner surface of the panel 1, and after drying, it is exposed to light through a shadow mask and developed. It will be done.

To apply such a phosphor slurry, generally, as shown in the first diagram, the phosphor slurry 3 is applied to the center of the inner surface of the panel 1 from the nozzle 2 while holding the panel 1 diagonally upward and rotating it at low speed. The panel 1 is then rotated at high speed to shake off and remove the excess phosphor slurry 3.

In this case, it is important to uniformly apply the phosphor slurry 3 to the inner surface of the panel 1. If the application is uneven, not only will the thickness of the obtained phosphor film become uneven, but also the phosphor film dots will become uneven. The edges become irregular, and the diameter of the phosphor particles in the phosphor film becomes uneven depending on the location, impairing the uniformity of image quality.

For this reason, various improvements have been made in the past in the composition of the phosphor slurry 3, the injection speed, the angle of the panel 1 during coating, the rotation speed, etc., but sufficient results have not yet been achieved.

The present invention was developed based on the above circumstances, and it is possible to uniformly coat the phosphor slurry to make the thickness of the phosphor film uniform, eliminate irregularities in the edges of the phosphor film dots, and It is an object of the present invention to provide a method for eliminating particle size deviation of phosphor particles depending on the panel position and forming a phosphor surface with good screen brightness and white uniformity.

As a result of various studies, the present inventors discovered that the injection position of the phosphor slurry has a significant effect on the thickness of the coating film and the positional deviation of the phosphor particle size. As a result, we found an appropriate non-injecting position,
The above objectives have been achieved.

That is, the present invention is characterized in that the phosphor slurry is injected at the periphery of the panel, and preferably the injection position is 1/4 of the major axis from the center of the panel.
The above distance is set at a distance of 1/2 or less of the short axis.

Hereinafter, the superiority of the present invention will be illustrated by giving experimental examples.

Example 1 A phosphor slurry 3 with a viscosity of 8 to 100 P is placed on the inner surface of the panel 1, which is rotating at an inclination angle of 7 degrees and a rotational speed of 8 rPm, at a position close to the panel center 4, as shown in Figures 2 a to d. 2a for coating, then the injection was stopped and the panel 1 was rotated at 180 rPm to shake off the excess phosphor slurry 3 and dry.

When injected in this manner, the first injected slurry 3a moves downward in the direction of the arrow due to gravity, as shown in FIG. 2a. During the next injection, the panel 1 rotates slightly (for example, 1/8 rotation), and as shown in Figure b, the slurry 3b injected later also moves downward, but the slurry 3b injected earlier
a points downward from a somewhat elevated position. Furthermore, when panel 1 rotates 1/8,
As shown, the slurry 3c injected at this time heads downward, and the slurry 3a injected first and the slurry 3b injected next overlap each other from their lifted positions and head downward. In this way, the slurry injected first has a trajectory from the center to the periphery, and the slurry injected later has a trajectory from the position lifted by the rotation of the panel 1 to the periphery. As shown in Figure d, the coating is applied over the entire surface, spreading from the center to the periphery. Therefore, the film thickness is greatest at the center of the panel 1 where the slurry 3 overlaps the most.

In addition, the flow speed of the slurry 3 is faster in the center of the panel 1 where injection is performed, and
Also in the peripheral area, the flow becomes faster due to pooling of the slurry 3. Therefore, large-sized phosphors are deposited in the middle part where the flow is slow.

In this way, overlapping streams of the slurry 3 and differential deposition of particle sizes occur, resulting in non-uniformity in coating thickness and positional non-uniformity in particle size.

Example 2 Hold the panel 1 and rotate at the same speed as in Example 1 above, set the injection position 2b of the slurry 3 at a position approximately 1/5 of the major axis L from the center 4 of the panel 1, and apply in the same manner as above. did.

The trails and flow velocities of the slurries 3a to 3c in this case, as shown in FIGS. 3a to 3d, have the same tendency as in Example 1, but the overlapping of the trails in the center is considerably less than in Example 1. , positional deviations in film thickness and particle size are largely alleviated.

However, in the center of the panel 1, there is no flow of the slurry 3 due to injection as in Example 1, and therefore the previously formed fluorescent film becomes a barrier to the flow of the slurry 3 applied later. , a thick fluorescent surface is formed in the direction in which the fluorescent film extends. When such a fluorescent surface is made to emit light, a striped part that appears particularly bright appears in the center along the direction in which the fluorescent film extends.

Example 3 The holding and rotation speed of the panel 1 are the same as in Examples 1 and 2 above, and the injection position 2c of the slurry 3 is set at a position slightly farther than 1/4 of the major axis L ₁ from the center 4 of the panel 1. It was applied in the same manner.

In this case, the flow of the slurry 3 on the inner surface of the panel 1 is different from that in the above-mentioned examples 1 and 2, and is different from that shown in FIG.
As shown in d, the water flows from the periphery of the panel 1 toward the center. In other words, most of the injected slurry 3 remains at the periphery of the panel 1, and as the panel 1 rotates, this pool of slurry 3 is steadily and sequentially lifted up and directed downward by gravity. As a result, the slurry 3 flows from the periphery of the panel toward the center. Moreover, the composition of the slurry 3 in the peripheral area of the panel 1 is almost the same when it is injected, and the phosphor particle size also hardly changes, so there is no positional variation in the thickness of the resulting phosphor film and the phosphor particle size. Uniformity will be resolved.

The thickness distribution of the fluorescent films obtained for the three examples mentioned above is shown in the graph of FIG. In this graph, the horizontal axis shows the position on the long axis of the inner surface of the panel 1 as the distance from the center 4, and the vertical axis shows the film thickness as a relative value with the thickness at the center 4 as 100 for each example. Curve A
curve B shows the local film thickness deviation of the fluorescent film obtained by the method of Example 1, curve B shows the method of Example 2, and curve C shows the local film thickness deviation of the fluorescent film obtained by the method of Example 3, respectively.

As is clear from this graph, it can be seen that the film thickness of Example 3 is extremely uniform compared to Examples 1 and 2.

Furthermore, the positional distribution of the phosphor particle size of the obtained phosphor films was investigated for the three examples mentioned above. The results are shown in the graph of FIG. In this graph, the horizontal axis shows the position on the long axis of the inner surface of the panel 1 in the same way as in FIG.
The content of small particles smaller than μ is calculated as a relative value for each example when the value at panel center 4 is taken as 100. Curve D is for example 1, curve E is for example 2, and curve F is
shows the positional deviation of the phosphor particle size of the phosphor surface obtained in each case by the method of Example 3.

As is clear from this graph, it can be seen that compared to Examples 1 and 2, Example 3 has a significantly smaller positional deviation in particle size.

In addition, when the fluorescent surface obtained in this way is made to emit white light, the one in Example 1 has a radius of 44 cm at the center of the screen.
It produces a particularly bright circle around cm, which seriously impairs the image quality. In addition, in Example 2, a particularly bright striped pattern about 2 cm wide appears in the center of the screen, which also significantly impairs the image quality. In comparison, in Example 3, the screen brightness was uniform and the image quality was significantly improved.

According to experiments, the present invention is effective if the injection position of the phosphor slurry is at least 1/4 of the major axis L from the center 4 of the panel 1, compared to a case where the injection position is less than 1/4 of the major axis L. There is a clear advantage. However, if the distance is more than 1/2 of the minor axis from the center 4 of the panel 1, the phosphor slurry 3 will be injected outside the panel 1, which is not preferable because not only will the slurry 3 be lost, but the panel 1 will be contaminated.

As described above, the method for forming a phosphor surface of a color picture tube according to the present invention includes injecting a phosphor slurry into the periphery of the inner surface of the panel, which is held obliquely upward and rotating at a low speed, and coating the inner surface of the panel; Then, the panel is rotated at high speed to remove the excess phosphor slurry, so that the thickness of the phosphor film is uniform, the positional deviation of the phosphor particle size is small, and the screen brightness is uniform.
Good white uniformity characteristics.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the phosphor slurry application process in a method for forming a phosphor surface of a general color picture tube;
Figures a to d are explanatory diagrams showing the first experimental example in the order of progress, Figures a to d are explanatory diagrams showing the second experimental example in the order of progression, and Figures a to d are the third experiment. An explanatory diagram showing an example in the order of progress, Figure 5 is a graph comparing and showing the local deviation of the film thickness of the fluorescent surface obtained by the above experimental example, and Figure 6 is a graph showing the fluorescence of the fluorescent surface as well. It is a graph showing a comparison of positional deviations in body particle size. 1... panel, 3... phosphor slurry, 2a,
2b, 2c... Injection position of phosphor slurry, 4...
...Center of the panel, L...Longer diameter of the panel.

Claims (1)

[Scope of Claims] 1. A phosphor slurry is injected into the periphery of the inner surface of the panel held obliquely upward and rotated at low speed to coat the inner surface of the panel, and then the panel is rotated at high speed to remove the excess of the above. A method for forming a phosphor surface of a color picture tube, comprising removing a phosphor slurry. 2. The color picture tube according to claim 1, wherein the injection position of the phosphor slurry is located at a distance of 1/4 or more of the major axis and 1/2 or less of the minor axis from the center of the panel. Method of forming a fluorescent surface.