JP2523603B2 - High definition shed mask - Google Patents

Description

TECHNICAL FIELD The present invention relates to a mask material and a shadow mask used for a cathode ray tube for a color television or the like.

[Conventional technology]

Generally, the properties required for a shadow mask material are (1) low thermal expansion, (2) good etching properties, good shape of perforations, and no streaking on the etched surface, 3) The shape has a high flatness. On the other hand, conventional rimmed steel and low carbon with improved required properties described in (2) and (3) above.
Al-killed steel has been used as a material.

[Problems to be solved by the invention]

However, with the trend toward higher definition of color TV,
The shape, size, and amount of non-metallic inclusions (hereinafter referred to as inclusions) that adversely affect the shape of perforations on the mask surface photoetched at a small pitch are increasing due to the increasing demand for higher definition of shadow masks. Has become a problem.

This problem is that if there is an inclusion in the etched hole, the inclusion is preferentially corroded due to the relationship between the etching solution and the composition of the inclusion, or conversely, only the base is corroded and the inclusion remains. That is, irregularities are formed in the perforated portion.

When the defective portion is irradiated with the electron beam, irregular reflection occurs, causing color shift of the image. Further, for higher definition, in a shadow mask having a small hole pitch and a high etching area ratio, there is a concern that defects may increase due to inclusions.

The object of the present invention is to perform various studies on the shape, size, and amount of inclusions so as not to cause color misregistration required for a shadow mask for high-definition color television, and have found appropriate conditions. Based on the shadow mask, and its material is to provide.

[Means for solving problems]

The present inventor has examined the relationship between the shape, size and amount of inclusions with respect to the shape of the etching perforated surface and the color shift of the image, and as a result, if the inclusions are within the ranges described below, the perforated part formed by the inclusions It was found that there is no adverse effect on the shape and the color shift of the image can be eliminated.

That is, the present invention provides a classification A of inclusions according to JIS G 0555 on the rolled surface and longitudinal section of the shadow mask.
The width of non-metallic inclusions is 5.0 μm or less and the length is 50 μm or less,
The width of the granular inclusions of the B-based non-metallic inclusions is 5.0 μm or less, the length is 50 μm or less, the average diameter of the single inclusions of the C-based non-metallic inclusions is 5.0 μm or less, and the A-based, B-based The value of the total cleanliness d (A + B + C) 60 × 400 of the system and C system is
A high-definition shadow mask having a perforation pitch of 0.5 mm or less, which is manufactured from an Fe-Ni-based Invar alloy steel sheet having a cleanliness of 0.01% or less.

In A-type non-metallic inclusions, when a group of inclusions that are continuous in the rolling direction is discontinuous, and when the interval is 5 times or more the size of the larger width of the two groups, two independent groups are formed. If it is less than 5 times, it is regarded as one group.

In the case of B type inclusions, when the distance between two inclusion aggregates continuous in the rolling direction is 5 times or more the size of the larger width of each aggregate, it is regarded as two independent groups,
When it is less than 5 times, it is regarded as one group.

In addition, the average diameter of a C-based single inclusion means a diameter obtained by converting the cross section of the inclusion into a perfect circle. As a result of investigating the relationship between the property of the inclusions and the color misregistration, a shadow mask having a perforation pitch of 0.5 mm or less, which belongs to high definition, was found to be as follows.

In the above inclusions, when the average diameter of the C-based single inclusions or the width of the A-based inclusions exceeds 5 μm, and even when the length of the A-based inclusions exceeds 50 μm, the shape of the perforated portion due to the inclusions Unevenness is harmful, and color misregistration occurs in the image. Further, when the width of the B-type inclusion group exceeds 5.0 μm and the length in the rolling direction exceeds 50 μm, the irregularities of the shape of the perforated portion due to the inclusions are harmful and cause color shift of the image.

In addition, in the result of measuring the amount of inclusions by microscopic observation based on JIS method, the area ratio d (A + B + C) 60 × 40
It was found that when the value of 0 is large, the uneven shape of the perforated part causes color misregistration of the image. Therefore, as a result of research and study, the area ratio d (A + B + C) 60 × 400 ≦ 0.0 as the cleanliness.
If it is 1%, it was found that the color shift of the image due to the defect in the shape of the perforated part can be ignored in practical use. In the present invention, the Invar alloy, Ni30-40%, desirably Ni34-37%, the balance of the alloy consisting essentially of Fe, or for these alloys, the purpose of increasing the strength or lowering the yield strength after annealing. The alloy containing a small amount of the third element is included.

〔Example〕

 Next, the present invention will be described in detail with reference to examples.

The test material is a vacuum melting and refining furnace, and C: 0.
01% or less, Si: 0.5% or less, Mn: 0.5% or less, S: 0.01% or less, Ni: 35 to 38%, Cr: 1.5 to 2.5%, V: 0.6 to 1.5%, balance
19 kinds of steel ingots shown in the table were obtained by adjusting the shadow mask material consisting of Fe and unavoidable impurities by combining high-purity material, thorough blowing of the bottom of argon gas, and expansion of ingot size. . The steel ingot was subjected to the steps of hot rolling → pickling → cold rolling → annealing → cold finish rolling to obtain a steel sheet for a shadow mask with a sheet pressure of 0.15 mm.

From this steel plate, we take a microscopic sample of the longitudinal section and surface,
The inclusions were measured, and at the same time, the steel plate was etched using a shadow mask to investigate the shape of the perforations and evaluated in accordance with the inclusion measurement results.

Two microscopic specimens, a longitudinal section and a surface, were taken, but since almost the same measurement results were obtained for both, the values of the longitudinal section are shown in the table.

Further, the shadow mask was incorporated into a color cathode ray tube and irradiated with an electron beam to confirm the presence or absence of color misregistration.

As a result, as shown in the table, by satisfying the conditions of the claims of the present invention, satisfactory results were obtained regarding the shape of the perforated portion and the color shift.

In the examples, the shadow mask having the above-mentioned component composition was melted and tested, but the present invention can be applied to other component compositions as long as it is a Fe-Ni-based low expansion material. Needless to say.

[Effects of the Invention] As described above, according to the present invention, the shape and size of the inclusions of the shadow mask, which requires high definition, and the amount thereof are not more than the specified values, so that the shape of the perforated portion is This is an industrially very useful invention because a shadow mask that is smooth and has no color shift can be obtained.

Claims (1)

(57) [Claims] 1. The width of a non-metallic inclusion A based on JIS G 0555 on the rolled surface and longitudinal section of a shadow mask is 5.0.
μm or less Length is 50 μm or less, width of granular inclusions of B type non-metallic inclusions is 5.0 μm or less Length is 50 μm or less, average diameter of single inclusion of C type non-metallic inclusions is 5.0 μm or less Yes, and the total cleanliness d of A system, B system and C system
(A + B + C) Fe-Ni whose value of 60 × 400 is 0.01% or less
High-definition shadow mask with a perforation pitch of 0.5 mm or less, manufactured from Invar alloy steel plate.