JPS6240528Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field of the Invention] The present invention relates to a shadow mask installed in a shadow mask type color picture tube. [Technical background of the invention] A shadow mask usually has a structure as shown in FIGS. 1 and 2. That is, the shadow mask 1 is formed by press-molding a flat mask (not shown), and includes an effective surface 3 in which a large number of electron beam passage holes 2 are formed, and a peripheral surface 4.
A bead portion 5 is provided between them, and a skirt portion 6 is formed from the peripheral edge surface 4 . The bead portion 5 is provided on the entire outer circumference of the effective surface 3 in order to prevent deformation of the effective surface 3 during press molding and maintain strength to maintain the shape. [Problems with the Background Art] However, in such a shadow mask, there are parts where it is not possible to maintain a sufficient distance between the bead portion 5 and the boundary between the effective surface 3 due to constraints such as the size of the outer periphery of the shadow mask and the deflection angle of the color picture tube. If the bead portion 5 is formed in this portion by press molding, the electron beam passage hole portion 2 on the effective surface 3 near the bead portion 5 is likely to be deformed due to partial elongation of the shadow mask 1, resulting in the shadow mask 1 being defective. There is a problem with this. [Purpose of the invention] The present invention was devised in view of the above-mentioned problems, and it is possible to improve the electron beam passage hole portion of the effective surface during press molding by changing the size of the bead portion depending on the distance between the effective surface and the bead portion. Almost eliminate the deformation of
The purpose of the present invention is to provide a shadow mask that can reduce the number of shadows. [Summary of the invention] That is, the present invention provides a shadow mask in which a bead portion is formed between an effective surface having a large number of electron beam passage holes and a peripheral surface, and the size of the bead portion is smaller than that of the effective surface. This shadow mask is characterized in that it is large at a position where the distance between the bead portion is large and gradually becomes smaller as the distance between the effective surface and the bead portion becomes shorter. [Embodiment of the invention] Next, an embodiment of the invention will be described with reference to FIGS. 3 and 4. That is, the shadow mask 11 is formed by press-molding a flat mask (not shown), and a bead portion 15 is provided between an effective surface 13 in which a large number of electron beam passage holes 12 are formed and a peripheral surface 14. A skirt portion 16 is provided from the bottom. This bead portion 15 is provided on the entire outer circumference of the effective surface 13 in order to prevent the effective surface 13 from being deformed during press molding and to maintain the strength to maintain the shape. Up to this point, it is almost the same as the conventional shadow mask 1, but in this embodiment, the bead portion ₁₅₁ having a long distance from the effective surface 13 is enlarged.
The bead portion 15 ₂ which is closer to the effective surface 13 than the bead portion 15 ₁ is smaller than the bead portion 15 1 and has a shorter distance from the effective surface 13 like the corner of the effective surface _{13 .}
is characterized in that it is made smaller than the bead portion ₁₅₂ . The relationship between the size B of the bead portion 15 and the distance A from the effective surface 13 is as shown in the table of results of experiments conducted by the present inventors using a shadow mask for a 14-inch color picture tube. Deformation of the electron beam passage hole 12 during formation could be minimized.

[Effect of idea]

As mentioned above, according to the present invention, it is possible to minimize the influence of the bead portion on the effective surface during press forming, especially in a shadow mask having a rectangular effective surface in which the distance between the bead portion and the effective surface changes, that is, a flat face. As a result, the deformation of the electron beam passage hole in the effective surface can be minimized, so a highly accurate shadow mask can be obtained, and its industrial value is extremely large.

[Brief explanation of the drawing]

1 and 2 are diagrams showing a conventional shadow mask. FIG. 1 is a plan view, FIG. 2 is a cross-sectional view for explaining the main part of FIG. 1, and FIGS. 3 and 4 are views of a conventional shadow mask. It is a figure showing one example of the shadow mask, and the third
The figure is a plan view, and FIG. 4 is a cross-sectional view for explaining the main part of FIG. 3. 2, 12... Electron beam passing hole portion, 3, 13...
...Effective surface, 4, 14...Peripheral surface, 5, 15, 15
₁ , 15 ₂ , 15 ₃ ...Bead part, 6, 16...
Skirt part.

Claims (1)

[Utility Model Claims] (1) A shadow mask having a bead portion formed between an effective surface having a large number of electron beam passing holes and a peripheral surface, the size of the bead portion being large where the distance between the effective surface and the bead portion is long and gradually becoming smaller as the distance between the effective surface and the bead portion becomes shorter. (2) A shadow mask as claimed in claim 1, characterized in that the bead portion is provided so as to surround the effective surface. (3) A shadow mask as claimed in claim 1, characterized in that the electron beam passing holes are approximately rectangular and connected in the longitudinal direction via bridges, and the bead portion is provided only in a direction approximately perpendicular to the longitudinal direction.