JPH05214490A - Stock for shadow mask - Google Patents

Abstract

PURPOSE:To provide stock for a shadow mask having a low thermal expansion coefficient as well as capable of forming a required fine electron beam passing hole with high accuracy and bringing many advantages in the respect of cost or the like. CONSTITUTION:This stock is obtd. by melting, e.g. aluminum killed steel components substantially consisting of iron and whose crystalline grains have >=8, preferably >=12 size number (by JISG0551), subjecting it to rapid cooling (by a double roll method) into a thin sheet or a thin strip and thereafter subjecting it to cold rolling into a one having about 0.13 to 0.25mm thickness. It is based on this knowledge that this kind of thin sheet or thin strip assumes the form of being constituted of fine crystalline grains having >=8 size number (by JISG0551) and its thermal expansion coefficient is reduced to about 5 to 10X10<-6>/ deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for a shadow mask, for example, a material for a shadow mask having a low coefficient of thermal expansion and fine workability suitable for a shadow mask structure of a color television.

[0002]

2. Description of the Related Art Generally, a shadow mask of a color television set is made of aluminum killed steel, but recently, a large-sized color television set of, for example, 29 inches or more is required to have a high definition image quality. Then, in response to such a demand, for example, 36 wt% nickel-iron (36% Ni-F
It has been attempted to construct a shadow mask using an amber alloy centered on e) as a material. That is, the amber alloy is a conventional aluminum kid steel (coefficient of thermal expansion 1
Its thermal expansion coefficient (1.2 × 10 ^-6 ) is smaller than that of 2.1 × 10 ^-6 ) by an order of magnitude, so even when the shadow mask is heated by electron collision, it can pass through the electron beam when used as a shadow mask. This is because it is difficult to cause positional deviation of the holes, and as a result, it is easy to reliably prevent color misregistration. The shadow mask is made of a thin plate having a thickness of, for example, about 0.25 μm, and crystal grains such as amber alloy are used to form fine electron beam passage holes (holes) almost uniformly by so-called photo-etching. Is desired to be fine.

By the way, the material for the shadow mask such as the aluminum killed steel or the amber alloy system is manufactured as follows. That is, it is manufactured through the steps of melting the raw material, hot forging, hot rolling, cold rolling, annealing, and adjusting rolling, and in the case of the aluminum-killed steel thus obtained, the grain size is 30 μm or more ( The grain size number specified in JIS G0551 is 7 or less), and in the case of adjusted rolling of amber alloy, it is 6 μm or more even if the crystal grains are fine (12 or less in the grain size number specified in JIS G0551). ..

[0004]

However, with the development and practical use of a large-sized and high-definition color TV, the shadow mask is also formed with high precision and fine electron beam passage holes (open holes). ) Is required, the cost aspect is also attracting attention. In other words, it is desirable that the shadow mask material not only has a small coefficient of thermal expansion, but that it can also be formed with the required fine electron beam passage holes with high precision, and that the processing cost for the material or for the shadow mask is low. The ability to hold down is also required. From this point of view, the finer the crystal grains, the finer the openings having the inner wall surface with good smoothness can be formed by photoetching, but in the case of the conventional amber alloy, the required fine electron There are problems that the steps such as press molding after forming the line passing holes (shading into a shadow mask), blackening treatment are complicated, or the yield is poor. On the other hand, aluminum-killed steel is superior to Amber alloy in terms of press molding (shaping of shadow mask) after forming electron beam passage holes, blackening treatment, etc. There are problems such as the formation of various electron beam passage holes and the occurrence of color shift due to the coefficient of thermal expansion. The present invention has been made in view of the above circumstances, and not only has a small coefficient of thermal expansion, but also enables the formation of required fine electron beam passage holes with high accuracy, which brings many advantages in terms of cost and the like. The purpose is to provide materials for use.

[0005]

The material for a shadow mask according to the present invention is essentially composed of iron and has a grain size of 8 or more, preferably 12 or more (according to JIS G0551). ..

According to the present invention, for example, an aluminum-killed steel component consisting essentially of iron is melted and rapidly cooled (by the twin roll method) to form a thin plate or strip,
When cold-rolled to a thickness of about 0.13 to 0.25 mm, the obtained sheet or strip takes the form of fine crystal grains with a grain size number (according to JIS G0551) of 8 or more, and has a thermal expansion coefficient of 5 It was made based on the finding that it is reduced to about 10 × 10 ^-6 / ° C.

Here, the material being substantially composed of iron means
For example, C: 50 pp or less, Si: 200 ppm or less, Mn: 4000 ppm or less, P: 300 ppm or less, S: 300 ppm or less, N: 300 ppm or less, O (oxygen): 1000 ppm or less, so-called inevitable impurity components, or Cr: 50 It means that the content of about 3000 ppm and Al: 50 to about 3000 ppm may include the allowable components. That is, in addition to the unavoidable impurity component, when used as a shadow mask, a Cr component may be added to facilitate formation of a blackened film (oxide film) for improving thermal conductivity. N and O in the inside may promote the reduction of crystal grains due to the bond with Al.

In the present invention, it is required that the crystal grains of the material essentially consisting of iron are fine grains having a grain size number (according to JIS G0551) of 8 or more. The reason for this is that the coefficient of thermal expansion cannot be sufficiently reduced, and therefore when mounted on a color TV as a shadow mask, the electron beam passage hole is displaced due to the temperature rise due to the collision of electrons, and the internal smoothness is good. This is because it has been experimentally confirmed that the electron beam passage hole having the wall surface cannot be formed with high accuracy. In addition,
According to the present invention, the present inventors have also confirmed that in the shadow mask material, the coefficient of thermal expansion decreases by about 10% when the grain size of the crystal grains (according to JIS G0551) increases by 1 (increases by 1). For example, inevitable impurities by weight
A book obtained by quenching a metal melt containing substantially 0.4% iron by the twin roll method to make a sheet or strip with a thickness of several mm and then cold rolling to a specified thickness. The following relationship was observed between the grain size number (grain size μm) and the thermal expansion coefficient of the shadow mask material according to the invention.

[0009]

[0010]

Since the material for the shadow mask according to the present invention is a low thermal expansion alloy having a thermal expansion coefficient of about 10 × 10 ^-6 / ° C or less, the electron beam passage hole formed even when the temperature is increased by the collision of electrons. This not only eliminates the risk of misalignment, but also keeps the crystal grains in a fine state, so it is possible to easily and accurately form the required fine electron beam passage holes by photoetching. It will be possible.

[0011]

EXAMPLES Examples of the present invention will be described below.

A molten metal prepared by melting a metal substantially composed of iron (Fe) containing 0.4% by weight or less of inevitable impurities at a temperature equal to or higher than its melting point is poured onto a twin roll rotating at a high speed and rapidly cooled. A thin plate having a thickness of 2.5 mm and a width of 800 mm was obtained. This thin plate was annealed at 700 ° C. for 1 hour and then cold rolled at a reduction rate of 94% to obtain a material for a shadow mask having a thickness of 0.15 mm. With respect to the shadow mask material thus obtained, the coefficient of thermal expansion was measured by a conventional method to find that it was 7.1 × 10 ^-6 / ° C, and the result of measuring the crystal grains according to JIS GO551 was
The particle size was No. 12 (particle size about 7 μm) or less.

On the shadow mask material (Example 1) obtained above, required electron beam passage holes were formed (opened) by so-called photoetching. Observation of the shadow mask material in which the electron beam passage hole was formed (opened) revealed that the inner wall surface of the electron beam passage hole had good smoothness as a whole, and the hole of a predetermined size was formed with high accuracy. Was there. In addition, since this shadow mask material exhibits excellent mechanical strength due to the small crystal grains, it was easy to handle in various operations.

Next, the electron beam passage hole is formed (open hole).
The above shadow mask material was press-molded, and then a blackening film was attached to form a shadow mask, and a color television was constructed using this shadow mask. Then, when the color television configured as described above was operated, a finely detailed image without color misregistration was obtained. In other words, it functioned as a color television that provided high-quality images with no discernible color shift.

In the above, the conditions for quenching the molten metal by flowing it on a twin roll rotating at a high speed are changed, and the crystal grains according to JIS GO551 have a grain size No. 14 (grain size about 3 μm.
), Coefficient of thermal expansion 7.1 × 10 ⁻⁶ / ° C .... Example 2, grain size number No. 7 (grains produced through the steps of melting raw material, hot forging, hot rolling, cold rolling, annealing, and adjusting rolling) Diameter about 12 μm
), Coefficient of thermal expansion 12.1 × 10 ⁻⁶ / ° C .... Each shadow mask material of the comparative example was obtained, and a shadow mask was created by the same processing and processing as described above. The results of the evaluations are shown in the following table together with the case of the first embodiment.

Table Thermal expansion coefficient Grain size number of crystal grains Presence or absence of color misalignment Example 1 7.1 × 10 ^-6 / ° C No.12 Very slight Example 2 5.6 × 10 ^-6 / ° C No.14 No Comparative example 12.1 × 10 ^-6 / ℃ No. 7 Yes In the above example, C, Si, and M are unavoidable impurities.
Although an example of using substantially iron as a raw material containing about 4000 ppm in total such as n, P, N, O was shown, it was added to the system including N, etc. As a component added to, for example, iron, which contains several thousand ppm or less in the form of single or mixed Cr, Al, etc., is used in the same way when the crystal grains constituting it are grain size number 8 or more. When applied to a TV, a fine-grained image with no color shift was obtained. In other words, it functioned as a color television that provided high-quality images with no discernible color shift.

[0017]

As described above, the shadow mask material substantially composed of iron according to the present invention has not only a small thermal expansion coefficient, but also the crystal grains are fine particles having a grain size number No. 8 or more according to JIS G0551. It has a grain shape. Therefore, the electron beam passage hole is formed (opened) by, for example, photoetching.
In addition, it is possible to form an electron beam passage hole with a uniform hole diameter with high accuracy, and to prevent the position shift of the electron beam passage hole due to the temperature rise due to the collision of electrons. , Clear and fine (high quality) images can be obtained without causing color shift. Moreover, the material for the shadow mask is not only excellent in howling resistance because the crystal grains are also fine-grained with a grain size number No. 8 or more,
It can be easily manufactured by the so-called twin roll quenching method,
In addition, the formation and processing of the shadow mask is easy, and there are advantages such as mass productivity and good yield.

[0018]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiichi Akiyoshi, No. 50, Kamimayube, Yobu District, Himeji City, Hyogo Prefecture, Ltd. Inside the Himeji Plant, Toshiba Corporation (72) Yoshikazu Oda, Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture No. 1 Incorporated company Toshiba Research Institute

Claims (1)

[Claims] 1. A material for a shadow mask, which is essentially composed of iron and has a grain size of 8 or more (according to JIS G0551).