JPH01197941A - Shadow mask - Google Patents

Abstract

PURPOSE:To stably manufacture a high-quality product by providing a porous section bored with many electron beam passing holes, a nonporous section and a skirt and providing multiple beads on the nonporous section. CONSTITUTION:A nearly rectangular porous section 22 bored with many electron beam passing holes is formed on the center portion of a spherical principal plane made of a low-thermal expansion alloy of a shadow mask 21, a nonporous section 23 is formed around this porous section 22. Two circular grooves (beads) 25a and 25b are formed on the nonporous section 23 so as to surround the periphery of the porous section 22. When the pull quantity of the porous section 22 is increased and the low-thermal expansion alloy is used as a mask material, the raw material of the porous section 22 is more strongly pulled in the peripheral direction, the plastic deformation of a curved surface is liable to occur, corrugated irregularities and peripheral dimples of the porous section 22 are reduced. A high-quality product can be stably manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Field of Industrial Application) The present invention relates to a shadow mask disposed in a color picture tube.

(Prior Art) Generally, a shadow mask is placed in a color picture tube,
The electron beam emitted from the electron gun is selectively transmitted and collided with a predetermined position on the phosphor screen.

FIG. 7 shows an example of such a conventional shadow mask.The shadow mask 1 has an approximately rectangular shape in which a large number of electron beam passing holes are bored in the center of the spherical main surface. A hole portion 2 is formed, and a non-porous portion 3 is formed around the hole portion 2. In addition, a skirt 4 is formed at the peripheral edge of the non-porous part 3 and is bent at a substantially right angle from the main surface, and the non-porous part 3 has an annular groove ( bead) 5 is formed.

In the conventional shadow mask 1 having the above configuration, the bead 5
As shown in FIG. 8, is formed at the same time when the perforated part 2 and the non-perforated part 3 are spherically stretched by press molding.

In FIG. 8, numerals 10 and 11 indicate punch and knockout, respectively.

This pulls the material of the perforated part 2 in the circumferential direction when forming the curved surface, makes it easier to cause plastic deformation of the curved surface, increases the shape retention strength of the curved surface, and prevents the deformation of the perforated part 2. As shown in FIG. 9, the occurrence of local dents 6 on the outer periphery of the perforated portion 2 and the occurrence of wavy irregularities 7 on the perforated portion 2 as shown in FIG. 10 are suppressed, and This is to maintain the shape of the hole 2 by increasing its tensile strength and the like.

(Problem to be solved by the invention) However, in recent years, cathode ray tubes have become flatter and larger, and the mask material is made of a low thermal expansion alloy that has more than twice the yield strength of conventional aluminum quilt steel and is difficult to plastically work. has come to be used.

For this reason, in the conventional shadow mask, as described above, the problem arises that wavy irregularities occur in the perforated portions and local dents occur in the outer periphery.

The present invention has been made in response to such conventional circumstances, and can reduce dents on the outer periphery and wavy irregularities that occur in the perforated portion during press molding compared to the conventional method, thereby improving the stability of high-quality products. The purpose of this invention is to provide a shadow mask that can be produced in a number of ways.

[Structure of the Invention] (Means for Solving the Problem) That is, the present invention includes a perforated part in which a large number of electron beam passage holes are formed, a non-perforated part surrounding the perforated part, and a skirt. The shadow mask is characterized in that a plurality of beads are provided in the non-porous portion.

(Function) In the shadow mask of the present invention having the above configuration, a plurality of holes are provided in the non-porous portion. Therefore, the amount of tension in the perforated portion increases compared to conventional shadow masks. For this reason, even when a low thermal expansion alloy is used as a mask material, the material of the perforated part is pulled more strongly in the circumferential direction, making it easier to cause plastic deformation of the curved surface, causing wavy irregularities in the perforated part, and The occurrence of external dents can be significantly reduced compared to the conventional method.

(Example) Hereinafter, details of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 show a shadow mask according to an embodiment of the present invention. In the shadow mask 21 of this embodiment, a large number of electron beams are placed at the center of a spherical main surface made of a low thermal expansion alloy. A substantially rectangular perforated portion 22 with a passage hole is formed, and a non-perforated portion 23 is formed around the perforated portion 22 . In addition, a skirt 24 is formed at the peripheral edge of the non-porous part 23 and is bent at a substantially right angle from the main surface, and the non-porous part 23 has two annular skirts surrounding the perforated part 22. Grooves (beads) 25a and 25b are formed. In addition, as shown in FIG. 4, this bead 25
a, 25b, the circumference ρa of the bead 25a formed at a position close to the perforated part 22 is shorter than the circumference (b) of the bead 25b formed at a position far from the perforated part 22.

In the shadow mask 21, beads 25a, 25
b is the press device 3 as shown in FIGS. 3 and 4.
0, the perforated part 22 and the non-perforated part 23 are formed at the same time when performing spherical stretch molding. Note that in FIGS. 3 and 4, numerals 31 and 32 indicate punch and knockout, respectively.

In the shadow mask 21 of this embodiment described above, the two beads 25a125b formed in the non-porous part 23 make it possible to increase the tensile strength of the curved surface during spherical stretch molding of the perforated part 22 and the non-porous part 23 compared to the conventional case. increases. Therefore, it is possible to prevent irregularities and extreme dents in the outer periphery that have conventionally occurred in the perforated portion 22. As a result, howling characteristics, which had been a problem with tube characteristics, can be improved, and a shadow mask with good quality can be manufactured. Moreover, such an effect is obtained when the circumference of the bead 5 of the conventional shadow mask 1 shown in FIG. When the sum of the lengths is equal to the circumferential length of the beads 5, the shape of the shadow mask becomes better and the howling characteristics are also improved compared to the case where only one bead 5 exists.

That is, it is better to provide a plurality of small beads than to provide one large bead.

In addition, in this embodiment, the beads 25a and 25b are formed at a position close to the perforated portion 22 with a circumference Jl of the bead 25a.
a is a bead 25 formed at a position far from the perforated portion 22
The circumference of b (although we have explained an example configured to be shorter than b, the circumference pa of bead 25a125b, J2b
may be the same.

In addition, by providing the inner bead 25a intermittently by omitting part of the corner as shown in FIG. 5 or omitting the short side part as shown in FIG. 6, it is possible to It is also possible to adjust the tensile strength of the curved surface.

[Effects of the Invention] As explained above, according to the shadow mask of the present invention,
It is possible to reduce the outer periphery dent A3 and wavy irregularities that occur in the perforated portion during press molding compared to the conventional method, making it possible to stably produce high-quality products.

[Brief explanation of the drawing]

Fig. 1 is a top view showing a shadow mask according to an embodiment of the present invention, Fig. 2 is a sectional view of the shadow mask shown in Fig. 1, and Fig. 3 explains the forming process of the shadow mask shown in Fig. 1. FIG. 4 is an enlarged cross-sectional view of the main parts of the press device shown in FIG. 3, and FIGS. 5 and 6 are top views showing modified examples of the shadow mask shown in FIG. 1. figure,
Fig. 7 is a perspective view showing a conventional shadow mask, Fig. 8 is an enlarged sectional view showing the main parts of a press device for explaining the process of forming the shadow mask shown in Fig. 7, and Fig. 9 is an outer periphery. FIG. 10 is a sectional view of a shadow mask for explaining dents, and FIG. 10 is a sectional view of a shadow mask for explaining wavy unevenness. 21・・・・・・・・・・・・・・・・・・・・・Shadow Mask 22・・・・・・・・・・・・・・・・・・
・・・Perforated part 23・・・・・・・・・・・・・・・・・・
・・・・Non-porous part 24・・・・・・・・・・・・・・・・
... Skirts 25a, 25b ... Bead applicant Toshiba Corporation Agent Patent attorney Suyama Sa - l'-' 22 Figure 1 Figure 2 and Figure 3

Claims (1)

[Claims] (1) In a shadow mask comprising a perforated part with a large number of electron beam passage holes, a non-perforated part surrounding the perforated part, and a skirt, a plurality of beads are provided in the non-perforated part. A shadow mask characterized by: