JPH0515020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing an aperture mask, which is a member constituting a shadow mask of a shadow mask type color cathode ray tube.

[Conventional technology]

FIG. 7 is a partially cutaway perspective view of a conventional shadow mask.
, a reinforcing frame 3 for holding this, and a spring 4 disposed around the frame 3, and the spring 4 is used to plant it on the skirt part of the panel of a color cathode ray tube (not shown). It is configured to be attached to the pin that is attached.

The aperture mask 2 is generally composed of a thin metal plate with a thickness of 0.1 to 0.3 mm, and the front face is usually approximately rectangular, with a front face formed into a nearly spherical shape, followed by a bending line 8. The front surface has a skirt portion 9 formed almost perpendicularly thereto, and a through hole 10 through which the electron beam passes, leaving a non-porous peripheral portion 7 of a predetermined width, is formed on a surface within a substantially rectangular effective contour line 6. The perforated curved surface part 5 and the non-perforated peripheral part 7 that follow this constitute a perforated curved surface part 5 formed in a predetermined pattern in the area, and the perforated curved surface part 5 and the non-perforated peripheral part 7 are formed on the inner surface of the panel on which the shadow mask 1 is attached. It is shaped into an almost spherical shape to match the curved surface.

[Problem that the invention seeks to solve]

A conventional aperture mask is a flat mask in which through-holes 10 are formed in a predetermined pattern using an etching method on a single thin metal plate, and the perforated curved surface portion 5 and non-porous peripheral portion 7 are made into a spherical surface by press molding. At the same time, a skirt portion 9 was also formed.

However, the aperture mask 2 manufactured by such a manufacturing method has the following problems, for example.

For example, recently, high current density electron beams have been used due to the need for higher resolution or improved brightness.
The temperature rise of the aperture mask due to the impact of the electron beam becomes large, and color shift occurs due to deformation due to aspiration. To solve this problem, an aperture mask is made of a nickel alloy thin plate containing a large amount of nickel and having a small aspiration coefficient.

However, nickel alloy thin sheets have poor workability in press forming, and therefore have the following drawbacks.

Normally, the precision of the curved surface of the perforated curved surface portion 5 is 0.3 mm.
However, since the nickel alloy thin plate has a large so-called spring back, it is extremely difficult to narrow the skirt portion 9 to a predetermined shape by narrowing it down to approximately the diameter at the bending line 8. , when this aperture mask 2 with poor bending accuracy is attached to the frame 3,
Since the deformation based on the error in the molding dimensions distorts the curved surface of the perforated curved surface portion 5, the precision of the curved surface is impaired and color shift etc. occur.

Nickel alloy thin plates are significantly more expensive than conventionally used iron plates, and there are no inexpensive alternative materials, resulting in high costs.

To give another example, as color cathode ray tubes become extremely large, extremely large aperture masks are required. It requires a lot of equipment, is difficult to obtain, and is extremely expensive.

In order to solve these problems, the first member forming the perforated curved surface part, the skirt part and the non-perforated peripheral part extending in the direction of the center which is bent approximately at right angles are respectively An idea has been to create an aperture mask by making separate materials and then joining them together.

Hereinafter, such a junction type aperture mask will be explained in some detail.

FIG. 1 is a front view of a conventional joint type shadow mask of this type, and FIG. 2 is a sectional view taken along the - arrow in FIG.

In the figure, 11 is a first member in which a through hole 10 is formed in a perforated curved surface portion 5 of a thin nickel alloy plate with a small coefficient of thermal expansion, and 12 is an iron plate that is easily formed by pressing and has a skirt portion 9 and The second member 12 has an L-shaped cross-sectional shape, and a non-porous peripheral edge 7 which is bent at a substantially right angle and extends toward the center. The outer surface of the joint 12a on the inner peripheral edge of the hole periphery 7 and the inner surface of the joint 11a on the outer peripheral edge of the first member 11 are overlapped with a width W over the entire circumference, and the overlapped joint 11a , 12a are welded by a method such as seam welding.

Aperture mask 2 configured as in this example
Since the perforated curved surface portion 5 is formed of a nickel alloy thin plate with a small coefficient of thermal expansion, deformation due to electron beam impact is less likely to occur, similar to the conventional aperture mask 2 made entirely of a nickel alloy thin plate. small.

On the other hand, since the second member 12 is made of an iron plate with good workability, there is little spring back during press molding, and the molding can be performed with a predetermined precision.
The perforated curved surface portion 5 is not distorted.

FIG. 3 is a front view of another example of a bonded aperture mask, and is a front view of an extra-large aperture mask.

In this example, the skirt portion 9a of the long side portion of the aperture mask 2 and the non-porous peripheral portion 7
a is composed of a second member 12, which includes a perforated curved surface portion 5, a non-perforated peripheral portion 7b following this, and a skirt portion 9b.
is composed of a first member 11, and the first and second members 1
1 and 12 are superposed joint parts 11a and 12
A is welded over the entire area by a method such as seam welding.

If configured as in this example, the first member 11
Since it is possible to use material with a width that does not include the skirt portions 9a on both sides, the material cost of the super-large aperture mask can be significantly reduced.

However, since the bonded aperture mask has a bonded portion on its outer periphery, it is extremely difficult to form a perforated curved surface portion with high precision.

This invention has been made in view of the above circumstances, and provides an aperture that allows highly accurate molding of a curved surface portion with holes even if there is a joint between the first member and the second member around the curved surface portion with holes. The purpose of the present invention is to provide a method for manufacturing a tea mask.

[Means for solving problems]

The method for manufacturing an aperture mask according to this invention is as follows:
forming a flat mask by overlapping the outer peripheral edge joint of the first member and the inner peripheral edge of the second member and welding the overlapping joint over the entire circumference; loading the flat mask into the press molding die so that the first member is oriented to abut against the convex curved surface of the punch of the press molding die over the entire surface; and an outer mold disposed around the outer periphery of the punch. holding the peripheral edge of the second member, and pushing out the punch to form the non-porous peripheral edge of the first member and the second member following it into a spherical surface, and facing the punch. a step of sandwiching the joint portion with the die; a step of releasing the holding of the peripheral edge of the second member; and a step of holding the joint portion between the punch and the die;
and a step of pushing the outer peripheral edge of the second member into the outer mold while holding the joint portion of the second member to form a skirt portion bent at a substantially right angle. shall be.

[Effect]

According to the manufacturing method of the present invention, the joint portion of the outer peripheral edge of the first member and the joint portion of the inner peripheral edge of the second member are overlapped, and the overlapped joint portions are welded over the entire circumference to form an integral piece. form a flat mask of
Thereafter, the first member forming the perforated curved surface portion is arranged so as to be in contact with the convex curved surface of the punch of the mold over the entire surface, and the joint portion of the first member and the second member is Since pressing is performed while being held between the punch and the die facing it, even if there is a joint between the first member and the second member around the perforated curved surface, the perforated High precision molding of curved surfaces can be achieved.

[Embodiments of the Invention] Hereinafter, a method for manufacturing an aperture mask according to the present invention will be explained with reference to FIGS. 4 and 5 using the bonded aperture mask shown in FIG. 1.

First, a flat mask 13 shown in FIG. 4 is manufactured.

The flat mask 13 includes a flat first member 11 in which a through hole 10 is formed in a surface area forming the perforated curved surface portion 5, a joint 11a of the outer peripheral edge of the first member 11, and a width. A flat second plate-shaped second frame is formed on the picture frame and has a large through hole that forms the joint 12a of the inner peripheral edge that overlaps with the W, and has a width that forms the non-porous peripheral edge part 7 and the skirt part 9 that follows this. The members 12 are overlapped at their joint portions 11a and 12a, and the joint portions 11a and 12a are welded over the entire area by a method such as seam welding to form an integral plate.

This flat mask 13 is formed using a mold shown in FIG. 5a. The mold 20 is composed of a punch 21, a die 22, an outer upper mold 23, and an outer lower mold 24, and is configured to be able to move up and down in the direction of arrow A using a pressing device and a slide mechanism (not shown). The lower surface of the punch 21 is formed into a convex curved surface 21a that has a spring back in addition to the spherical shape of the aperture mask to be formed.
The outer shape of the die 22 matches the outer shape of the punch 21, and only its peripheral edge is formed into a concave curved surface 22a that rubs against the convex curved surface 21a of the punch 21 over the entire circumference. In addition, an outer upper mold 23 and an outer lower mold 2
4 is formed into a curved surface with opposing peripheral edges rubbed together.

First, as shown in FIG. 5a, the flat mask 13 is loaded into the mold 20. In this case, the first
The joint portions 11a and 12a of the second member are connected to the die 22.
It is placed on the concave curved surface 22a of the peripheral edge of.

Next, as shown in FIG. 5b, the outer upper mold 2
3 in the direction of arrow B, flat mask 13
The second member 12 at the peripheral edge of the outer lower mold 2
Hold firmly between 4 and 4.

After this clamping, as shown in Figure 5c, punch 2
1 in the direction of arrow C, flat mask 1
3 along the convex curved surface 21a of the punch 21, the perforated curved surface portion 5 is formed into a spherical surface by the first member 11, and the non-perforated peripheral portion 7 is formed into a spherical surface by the second member 12, and joined. Parts 11a, 12a
is firmly held between the peripheral edge of the convex curved surface 21a of the punch 21 and the concave curved surface 22a of the peripheral edge of the die 22.

Furthermore, as shown in FIG. 5d, the outer upper mold 2
The pressing force applied to the punch 21 is loosened, and a stronger pressing force is applied to the punch 21 to push it down in the direction of arrow D. In this process, the punch 21 and die 22
moves in the direction of arrow E while holding the flat mask 13, is pushed into the outer lower mold 24, and is squeezed from the bending line 8 to form the skirt portion 9.

Finally, the pressing force of the punch 21 and the outer upper mold 23 is released, and the punch 21 is pulled upward.
The molded aperture mask 2 is taken out.

In this forming process, the joint parts 11a and 12a of the first and second members are held between the punch 21 and the die 22, and the convex curved surface 21a of the punch 21
Since the perforated curved surface part 5 of the member 11 and the peripheral edge following it contact over the entire surface and are molded into a spherical surface, it is difficult to mold a single flat mask despite the presence of the joint parts 11a and 12a. It can be molded with similar curved surface accuracy.

Note that if the joint parts 11a and 12a are firmly welded over the entire area, the joint parts 11a and 12a
It is not necessary that the die be sandwiched between the punch 21 and the die 22.

Furthermore, in the molding step shown in FIG. 5c, the flat mask 13 may slip at the portion sandwiched between the punch 21 and the die 22, and in the molding step shown in FIG. 5d, when forming the skirt portion 9. In order to prevent the accuracy of the perforated curved surface portion 5 from being impaired due to the influence of , 22b are provided, and at the joint portions 11a and 12a of the flat mask 13,
An annular bead may also be formed.

Next, a method of manufacturing an aperture mask in which the second member as shown in FIG. 3 is partially disposed around the outer periphery of the first member will be described.

Also in this case, it has the width and length necessary to form the perforated curved surface part 5, the non-perforated peripheral part 7b on the short side following this, and the skirt part 9b, and forms the perforated curved surface part 5. The first member 11 has through holes 10 formed in a constant pattern in the surface area thereof, and is formed to have the width and length necessary to form the non-porous peripheral portion 7a on the long side and the skirt portion 9a following this. two second
A flat mask 13 is formed by overlapping the members 12 by the width W and welding them over the entire area by a method such as seam welding, and then molding the same using the mold 20. An aperture mask 2 as shown in FIG. 3 can be manufactured.

〔Effect of the invention〕

In the method for manufacturing an aperture mask according to the present invention, the entire curved surface with holes is brought into contact with the convex curved surface of the punch of the mold, and the joint portion is sandwiched between the punch and the die facing the punch. Since pressing is performed, a highly accurate aperture mask can be obtained even if there is a joint where the first and second members overlap.

[Brief explanation of the drawing]

FIG. 1 is a front view of an example of an aperture mask to which the manufacturing method of the present invention is applied, FIG. 2 is a sectional view taken along the - line in FIG. A front view of another example of the aperture mask, FIG. 4 is a plan view showing the shape of the flat mask in the middle of the process in the manufacturing method of the present invention, and FIGS. 5 a to d are presses forming a part of the manufacturing method of the present invention. FIG. 6 is an enlarged sectional view of essential parts for explaining the press molding process of another embodiment, and FIG. 7 is a partially cutaway perspective view of a conventional shadow mask. 2...Aperture mask, 5...Perforated curved surface part,
7, 7a, 7b... non-porous peripheral portion, 9, 9a, 9b
... Skirt part, 10 ... Through hole, 11 ... First member, 11a, 12a ... Joint part, 12 ... Second
members, 13...Flat mask, 21...Punch, 22...Die, 23...Outer upper mold, 24...
...Outer lower mold, 21b, 22b...Bead forming part. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first member in which through-holes through which electron beams pass are formed in a predetermined pattern and formed in a perforated curved surface portion having a predetermined shape, a skirt portion, and a skirt portion extending toward the center bent at an approximately right angle following the skirt portion. In the method for manufacturing an aperture mask, the overlapping portion with a second member formed with a non-porous peripheral portion is welded, wherein the joint portion of the outer peripheral edge of the first member and the second member are welded together. A step of forming a flat mask by overlapping the joined portions of the inner circumferential edges of the first member and welding the overlapping joined portions all around the circumference, and a step of making the first member entirely contact the convex curved surface of the punch of the press molding die. loading the flat mask into a press molding die so that they are in contact with each other; holding the peripheral edge of the second member with an outer die disposed around the outer periphery of the punch; Extrude the first member and the second member following this.
a step of forming a non-porous peripheral portion of the second member into a spherical surface and sandwiching the joint portion between the punch and a die opposing the punch; a step of releasing the holding of the peripheral portion of the second member; Pushing the outer peripheral edge of the second member into the outer mold while holding the joint portion of the first and second members between the punch and die to form a skirt portion bent at a substantially right angle. A method for manufacturing an aperture mask, comprising the steps of: