JPH0594767A - Original plate for shed mask and shed mask - Google Patents

Abstract

(57) [Abstract] [Purpose] In a master plate for a shadow mask made of a metal alloy having a low thermal expansion property such as amber alloy, it is possible to eliminate the variation in the diameter and shape of the holes formed by etching and to transmit the permeation matrix Avoid streaks in the light. A metal original plate 1 used when manufacturing a shadow mask, and a shadow mask is obtained by forming electron beam transmitting holes. The plate thickness variation Δt between the width of the region where the electron beam transmitting hole is formed and the length thereof in the longitudinal direction of 50 mm is 1.5 μm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal original plate used for producing a shadow mask for a color picture tube and a shadow mask using the same.

[0002]

2. Description of the Related Art In general, a shadow mask having a large number of apertures, which is formed in a matrix in accordance with a predetermined design standard, is arranged immediately in front of a fluorescent screen of a color picture tube. Then, the electron beam emitted from the rear electron gun passes through the aperture of the shadow mask and is applied to the fluorescent dot at a predetermined position on the fluorescent screen, so that a color image appears. However, not all of the electron beams emitted at this time pass through the aperture, and the electron beam that passes through the aperture is about 1/3 or less of the whole, and the rest of the electron beams hit the shadow mask directly. This is heated. as a result,
Since the shadow mask is thermally expanded and the positions of the openings are displaced from the design standard, the shadow mask may cause a color shift phenomenon on the fluorescent screen. Therefore, recently, it has a low thermal expansion property.
Fe-Ni alloy, for example 36wt% Ni-Fe alloy (Amber alloy)
It has been attempted to prevent the color shift phenomenon by configuring the shadow mask itself.

By the way, as a method for producing a shadow mask original plate from such an Fe--Ni alloy, first, forging, rolling, etc. are carried out by a conventional method on a melt-cast material mass adjusted to a predetermined alloy composition. A method of applying a treatment to a predetermined thickness and cutting into a required width dimension is adopted. And conventionally, the plate thickness of the original plate thus obtained is defined as a variation value measured in the range of the total length in the rolling direction and the completed width in the width direction, for example, 3 μm in the width direction (direction orthogonal to the rolling direction).
Hereinafter, it is set to 7 μm or less in the longitudinal direction (rolling direction). Further, in order to manufacture a shadow mask by etching the opening positions of such an original plate, first, a photoresist is applied to the original plate to form a resist film, and then a shadow mask pattern is printed on a glass plate. The negative (negative) is placed on the plate provided with the resist film and brought into close contact by vacuuming. Next, after irradiating light (UV light) from a mercury lamp or the like to expose the resist film, the resist film is developed, dried and baked in order, and then corroded by an etching solution to form an opening.

[0004]

However, in the conventional shadow mask original plate, even if the above-mentioned plate thickness standard is sufficiently satisfied, the opening hole (electron beam transmitting hole) formed by etching is formed. In some cases, the diameters and shapes were non-uniform, and when irradiating the apertures with light and observing the transmitted light, streak-like unevenness was observed in some of the width and length directions. Under these circumstances, it is difficult to say that the recent demand for high definition in color picture tubes has been sufficiently satisfied.

The present invention has been made to address such a problem, and a first object of the present invention is to suppress variations in hole diameter and hole shape when forming openings. A second object of the present invention is to provide a high-quality original plate for a shadow mask, and a second object of the present invention is to provide a shadow mask in which streaks are prevented from occurring when light is transmitted through the openings.

[0006]

The shadow mask original plate of the present invention is a metal original plate having electron beam transmitting holes formed therein and used for manufacturing a shadow mask, wherein the electron beam transmitting holes are formed. The feature is that the plate thickness variation between the widthwise and longitudinal directions of the region of 50 mm is 1.5 μm or less.

The shadow mask of the present invention is characterized by using the above-mentioned shadow mask original plate.

In the metal alloy original plate for a shadow mask of the present invention, as shown in FIG. 1, in addition to the regulation of the plate thickness variation Δt ₀ as a whole of the original plate 1, the plate thickness variation Δ in a short range of 50 mm in length Δ t is specified to be 1.5 μm or less. In this way, by making the plate thickness variation Δt in the short range of 50 mm in both the width direction and the longitudinal direction to be 1.5 μm or less, the diameter and shape of the holes formed by etching can be made uniform. ..

That is, the part where the plate thickness variation is locally large
If (1.5 μm or more / 50 mm) is present, the time required to open the specified aperture diameter by etching changes when forming the electron beam transmission aperture, and the aperture diameter of the adjacent portion is extremely different. Is. On the other hand, when the plate thickness variation with respect to the length of a short range such as 50 mm is gentle, the diameter and shape of the holes in the adjacent portions can be made substantially uniform, so that the transmitted light has uneven streaks. It can be prevented from occurring. Above short range thickness variation △
A more preferable value of t is 1 μm or less / 50 mm. Further, this short range plate thickness variation Δt is evaluated for the entire region in which the electron beam transmission hole is formed, and the plate thickness variation Δt ₀ as a whole conforms to the conventional regulation. ..

The material constituting the original plate for the shadow mask of the present invention is not particularly limited, and various alloys can be applied, for example, Ni-Fe type alloy, Ni-Cr-Fe.
Examples include series alloys, Ni-Co-Fe series alloys, Ni-Co-Cr-Fe series alloys, and the like.

In the present invention, attention is paid to the fact that even if the conventional width direction plate thickness variation is controlled to 3 μm or less and the longitudinal direction plate thickness variation is controlled to 7 μm or less, there is often a streak unevenness. As a result of careful examination, it became possible to distinguish between the plate thickness fluctuation Δt ₀ as a whole and the plate thickness fluctuation Δt in a short range.

The streak is a region where the hole diameter of the electron beam transmitted light formed by etching is abruptly larger than the surrounding area (a bright area of the transmitted light) or an area where the hole diameter is abruptly smaller than the surrounding area (of the transmitted light). Dark areas) occur in stripes. Moreover, this contrast is symmetrical, and if the difference with respect to the surroundings is abrupt, it is distinguished as streaks. If this difference is gradual, it is not a problem in practice.

Here, the hole diameter of the electron beam transmitted light formed by etching is greatly influenced by the plate thickness, and for example, a fluctuation of the plate thickness of 1 μm results in a fluctuation of the hole diameter of 2 μm to 3 μm. For this reason, in the present invention, it has been found for the first time that if the thickness variation Δt in the short range is 1.5 μm or less, it is possible to prevent streaking, which is a problem in practical use, and it is within the scope of the present invention. It was defined.

The shadow mask original plate of the present invention is manufactured, for example, as follows.

That is, first, a molten mass adjusted to have a desired alloy composition is cast to produce a mass of material. Then, for example, 10
Hot rolling is performed at 50 ° C to 1250 ° C, and after descaling, cold rolling and annealing are repeated to obtain desired dimensions. On this occasion,
A polishing process is performed in the middle to improve the surface quality.The surface of the polishing roll used in this polishing process, wheel grinder, etc. Management of abrasives and control of polishing conditions. Further, during cold rolling, roll stop, chattering due to imbalance between tension and reduction ratio cause abrupt dimensional variation in a short range, and therefore it is necessary to control the balance between tension and reduction.

By adopting such a manufacturing method,
Short range (50 mm) thickness variation can be 1.5 μm or less.

[0017]

EXAMPLES Examples of the present invention will be described below.

Examples 1 to 3 First, a 36 wt% Ni-Fe alloy having a predetermined composition, a so-called amber alloy, is melted, cast, hot-rolled, surface-ground, cold-rolled and annealed repeatedly, and finally dull-rolled. Each step of slitting was performed in order to manufacture three kinds of shadow mask original plates. The thickness of each original plate was 0.25 mm, and the conditions of surface grinding and cold rolling in the manufacturing process were changed. In Example 1, the reduction of the surface abrasive (wheel grinder) was made uniform, and the surface of the wheel grinder was dressed to prevent the occurrence of local unevenness, and in Example 2, the balance between the reduction pressure and the tension during cold rolling. Then, roll slip and roll stop were prevented, and Example 3 was a combination of Examples 1 and 2 above. By these, the local thickness variation was variously changed. The variation (μm / 50 mm) in the width direction and the length direction of each shadow mask original plate was as shown in Table 1. At the same time, the variation of the plate thickness as a whole was also measured.

Further, as a comparison with the present invention, the conditions of surface grinding and cold rolling in the manufacturing process are set as ordinary steel plate rolling conditions, and the variation of the plate thickness in the width direction and the longitudinal direction is outside the range of the present invention. A master plate was prepared. The variation of the plate thickness in the poles in the width direction and the longitudinal direction was as shown in Table 1.

Next, after degreasing the surface of each of the shadow mask original plates obtained in the above Examples and Comparative Examples, a photosensitive solution was applied to both surfaces to form a resist film. Next, a negative having large and small hole patterns was placed on the resist films on both sides, and after being brought into close contact with each other by evacuation, the resist film was exposed to light from behind the negative by an ultrahigh pressure mercury lamp. After that, after development, drying, baking and curing,
Etching was performed using a ferric chloride solution to form electron beam transmission holes.

The shadow mask manufactured in this manner was observed with transmitted light in a dark room to evaluate the uneven quality. The results are shown in Table 1. As for the unevenness quality, there is no unevenness, and particularly good quality is A. If there is little unevenness, good quality is B. If there is some unevenness but there is no problem in practical use, there is unevenness and it is not practical. The thing was designated as D.

[0022]

[Table 1]

As is clear from Table 1, the shadow mask original plates according to the respective examples have a slight variation in plate thickness locally, and therefore, a shadow mask of good quality without streaks is obtained. On the other hand, in the shadow mask original plate according to each comparative example, since the plate thickness variation at the extreme part is large, the obtained shadow mask has strong streak unevenness and cannot be put to practical use.

[0024]

As described above, according to the original plate for a shadow mask of the present invention, since the variation of the plate thickness is suppressed locally, the variation in the diameter and shape of the holes formed by etching is small. Therefore, it is possible to obtain a high-quality shadow mask having no streaks. Therefore, it is possible to obtain a shadow mask that meets the design criteria and is excellent in performance, and it is possible to sufficiently satisfy the recent demand for higher definition of the color picture tube.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a shadow mask original plate of the present invention.

[Explanation of symbols]

 1 ... Shadow mask original plate

Claims (2)

[Claims] 1. A metal original plate having electron beam transmitting holes formed therein, which is used for manufacturing a shadow mask, wherein a plate having a length of 50 mm in a width direction and a longitudinal direction of a region where the electron beam transmitting holes are formed. Thickness variation
An original plate for a shadow mask, which has a thickness of 1.5 μm or less. 2. A shadow mask using the original plate for a shadow mask according to claim 1.