JPS6326498B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cathode ray tube panel, and more particularly to a cathode ray tube panel in which the surface roughness of an inner wall surface forming a fluorescent surface is improved. For example, the inner wall surface of a black stripe type color picture tube panel is formed with an appropriate surface roughness (irregularities) to improve the adhesion of the photosensitive resin and fluorescent film used to form the black stripe to the panel inner wall surface. There is. In order to obtain a good black stripe, the surface roughness of the inner wall surface of the panel is determined empirically.
It is said that a surface roughness of about 0.2 μRz to 5.0 μRz is desirable, but in reality, a finer surface roughness provides a better black stripe. However, from the perspective of forming a fluorescent film,
Normally, the particle size of the phosphor particles that form this fluorescent film is usually about 5μ on average, the minimum is 1μ, and the maximum is 13μ to 15μ.
If the surface roughness is increased to a certain degree, the difference in particle size from the phosphor particles becomes large, and if a fluorescent film is formed on the inner wall surface of the panel in such a state, the adhesion force of the fluorescent film to the inner wall surface of the panel will increase. becomes weaker, which tends to cause undesirable results such as the fluorescing film falling off. As mentioned above, the surface roughness of the inner wall surface of the panel must be determined by considering both the black stripe and the phosphor film, but usually the formation of the black stripe is focused on, and the roughness of the inner wall surface is determined based on the phosphor surface. It is applied around 0.5 μRz over the entire inner wall surface to be formed. However, in recent years, phosphors with good luminous efficiency have been developed with the aim of improving the brightness of the phosphor surface of color picture tubes.
As this phosphor, a so-called large particle phosphor having a large particle size has come to be used. Next, Table 1 shows examples of particle sizes of conventional phosphors and large particle phosphors.

[Table] When using a large particle phosphor as shown in the previous table, it became difficult to perform stable screening with the conventional surface roughness, that is, around 0.5μRz. Therefore, the inventors tested the relationship between the quality of the black stripe and the adhesion force of the large particle phosphor with respect to various roughnesses of the inner wall surface, and obtained the results shown in Table 2.

[Table] However, the test was conducted with the pitch and width of the black stripes constant. In Table 2, ○ indicates good, △ indicates slightly good, and × indicates poor, and the roughness is the 10-point average roughness (Rz). As can be seen from this test result, the surface roughness of the inner wall surface
Between 0.5μRz and 2.0μRz, preferably between 0.5μRz and
Although it is possible to produce 1.5μRz by compromising both the black stripe quality and the adhesion of the phosphor, this is not a satisfactory quality, and some kind of countermeasure was needed to ensure stable production. The present invention has been made in view of the above-mentioned drawbacks, and provides a cathode ray tube panel in which the inner wall surface has surface roughness so that the black stripe quality is good and the adhesion of the phosphor is stable. The purpose is to That is, in the present invention, the surface roughness of the central part of the inner wall surface forming the fluorescent surface is made to be continuously or discontinuously greater than the surface roughness of the peripheral part, and the surface roughness is By setting it to 1.5μRz to 10μRz in the center and 0.5μRz to 1.5μRz in the peripheral area, it is possible to obtain a high-quality black stripe and perform stable screening of the phosphor. It became. Next, the reason why a good black stripe can be obtained and stable screening can be performed by providing the surface roughness at the center part and the surface roughness at the peripheral part of the inner wall surface of the panel will be explained. First, let's talk about black stripes. That is, since the black stripe provides adjustment margin (guard band) for the deflection device, it is usually necessary to make the width of the black stripe narrower at the periphery of the panel than at the center. As an example, 20
Curve 1 shows the black stripe width in inches and the black stripe width of a shadow mask type color picture tube. As can be seen from the figure, the black stripe width is approximately 0.17 mm at the center and approximately 0.12 mm at the periphery. In this case, the width of the opening of the shadow mask is 0.18 mm to 0.185 mm both at the center and at the periphery, and it is technically difficult to obtain the black stripe width as shown in FIG. 1 from such openings. Next, a method of exposing black stripes will be explained with reference to FIG. That is, when substantially spherical shadow masks 3 are disposed at predetermined intervals on a spherical panel 2 and light is exposed from the light source 4 through the opening of the shadow mask 3 via a correction lens (not shown), the central portion of the panel 2 is exposed. That is, the luminous flux 5 on the tube axis Z has a narrow width and strong light intensity as shown by the curve 7 in FIG. 3, and the black stripe width is relatively wide as shown in FIG. Since the film is sufficiently baked, the film forming conditions for this porous resin are not very demanding, and the surface roughness of the inner wall surface has little to do with deterioration of the black stripe quality. However, as shown by curve 8 in FIG. 4, the light beam 6 at the peripheral edge has a wide width and low light intensity, and it also comes into contact with the inner wall surface of the panel at an angle, so that the desired narrow black stripe width can be achieved. Baking on the photosensitive resin must be performed at a location where the light intensity is weak. The black stripe 9 indicated by diagonal lines in the figure has an incomplete shape and a good black stripe width cannot be obtained. In this case, of course, in order to obtain good black stripes, it is possible to obtain good black stripes by increasing the light intensity using a correction filter and increasing the exposure amount by extending the exposure time. It is not possible to obtain the stripe width. Therefore, currently the inner wall surface of the panel is uniformly coated with approximately
The black stripes 10 indicated by diagonal lines in FIG. 6 are formed by improving the film forming properties of the photosensitive resin by setting the surface roughness to about 0.5 μRz. In other words, according to our experience, in order to form a good black stripe, the surface roughness of the inner wall surface of the panel must be
It was said that about 0.2μRz to 5.0μRz is desirable, but
This is the result of paying particular attention to the periphery of the inner wall, and when focusing on the center of the inner wall, the
Good black stripes can be obtained even between 10 μRz and 10 μRz. Next, the reason why the panel of the present invention enables a stable striped phosphor film coating process, so-called screening, will be explained. In other words, when using large-particle phosphor on a panel with a surface roughness of about 0.1μRz to 0.5μRz, the position where the phosphor is difficult to adhere to the inner wall of the panel is the position where the black stripe width is wide, that is, the central part. If the surface roughness is increased only in this central part, stable screening becomes possible. Further, the reason why the phosphor is difficult to adhere to the central part of the inner wall surface of the panel is as follows. That is, to form a phosphor layer, for example, a phosphor slurry is prepared by mixing a phosphor with a photosensitive resin containing polyvinyl alcohol and dichromate, and this phosphor slurry is applied to the inner wall surface of the panel. Apply evenly using a spin coating method and then dry. Next, as in the case of the black stripe, it is exposed to light through a shadow mask, and then developed with hot water to remove the unexposed areas and form a phosphor layer of the first color. These steps are repeated for the phosphor layers of the three colors to form a phosphor surface that emits light in the three colors. During the so-called screening process in which a phosphor slurry is injected onto the inner wall of the panel and coated by spin, phosphors with larger particle sizes are precipitated earlier than phosphors with smaller particle sizes, and are simultaneously spin-coated. Therefore, large particles of phosphor are applied to the center of the panel, and small particles of phosphor are applied to the periphery of the panel, but if the surface roughness of the center of the panel is small, the phosphor will be The adhesion between the body and the inner wall surface of the panel is weak, and a phenomenon occurs in which the exposed phosphor slurry falls off with hot water during development. However, in this case, if the surface roughness is made large only in the central part of the panel, for example to the same level as the average particle diameter of the phosphor, the adhesion between the panel and the large particle phosphor is improved and stable screening can be performed. As an example of the surface roughness of the inner wall surface of the panel mentioned above, as shown by curve 11 in FIG.
The roughness may be set to 8μRz, and the roughness may be changed continuously from 2μRz to 1μRz at the periphery while gradually decreasing, or the surface roughness may be changed discontinuously at the center and the periphery. You may let them. In this way, by increasing the surface roughness of the panel's inner wall surface at the center and decreasing it at the periphery, it is possible to obtain almost the same black stripe quality as a conventional panel with a roughness of approximately 0.5 μRz. It was also possible to reduce dot drop defects of large particle phosphors by about 90%. This means that the quality of film formation in the central portion has improved. Further, by increasing the surface roughness of the central portion, the large particle phosphor adheres well to the central portion, which has the advantage of improving brightness. Of course, the cathode ray tube panel of the present invention can obtain good results against dot drop even when conventional phosphors are used. Furthermore, the present invention is not limited to panels for color picture tubes, and substantially the same effects can be expected for panels for cathode ray tubes on which other fluorescent surfaces are deposited. In the above explanation, it was explained that the roughness at the center of the panel is preferably about the same as the particle size of the phosphor, but this depends on the combination of the light intensity during exposure, the particle size of the phosphor, the slurry spin coating conditions, etc. It goes without saying that the surface roughness of the inner wall surface of the panel can be selected within the scope of the claims, and the change in surface roughness from the center to the periphery can be determined by a linear function, quadratic function, etc. It is also possible to change it continuously along the curve. The method for producing a cathode ray tube panel of the present invention is to use a press die having a predetermined surface roughness during panel molding, or to take advantage of the fact that the panel has a predetermined concave surface to perform chemical etching using hydrofluoric acid or the like. can also be formed. The surface roughness of the inner surface of the panel described above is defined by the difference in height between adjacent roughness protrusions and depressions. As described above, the cathode ray tube panel of the present invention has an extremely large industrial value because various advantages can be obtained by varying the surface roughness of the inner wall surface between the central portion and the peripheral portion.

[Brief explanation of the drawing]

Fig. 1 is a curve diagram showing the change in stripe width depending on the distance from the center of the panel, Fig. 2 is an explanatory diagram showing the luminous flux at the center and peripheral parts in the exposure process, and Fig. 3
The figure is a curve diagram showing the light intensity in the center part of Figure 2, Figure 4 is a curve diagram showing the light intensity in the peripheral part of Figure 2, and Figure 5 is a curve diagram showing the light intensity in the peripheral part of Figure 2. FIG. 6 is an explanatory diagram showing the shape of the black stripe formed on the periphery where film formation is good. FIG. FIG. 3 is a curve diagram showing the relationship between distance from the center of the panel and surface roughness. 2... Panel, 3... Shadow mask, 4...
Light source, 5, 6... luminous flux.

Claims (1)

[Scope of Claims] 1. The inner wall surface forming the fluorescent surface is characterized in that the surface roughness of the central portion thereof is continuously or discontinuously greater than the surface roughness of the peripheral portion. Cathode ray panel. 2. The cathode ray tube panel according to claim 1, wherein the surface roughness of the central portion is 1.5 μRz to 10 μRz, and the surface roughness of the peripheral portion is 0.5 μRz to 1.5 μRz.