JPS6282630A - Shadowmask member - Google Patents

Abstract

PURPOSE:To reduce the coefficient of thermal expansion of shadowmask thus to eliminate the color shift by employing a three layer structure where the opposite faces of an inner layer section composed of invar alloy are held between an outer layer section composed of soft steel while setting specific volume ratio between the inner and the outer layer sections. CONSTITUTION:A shadowmask member is formed into three-layer structure where invar alloy (for example, 36% Ni-Fe) at the inner layer section is held between soft steel at the outer layer section from the opposite faces. The volume ratio between the inner and the outer layer sections is set to 0.15-0.5. The modulus of elasticity and the durability will deteriorate for the volume ratio lower than 0.15 while the coefficient of thermal expansion will increase excessively for the volume ratio higher than 0.5. With such arrangement, color shift will never occur because of low coefficient of thermal expansion while good pressing performance is realized because of limited durability and the mask is never deformed because of high modulus of elasticity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Ordinary Application] The present invention relates to a shadow mask member provided in a color cathode ray tube, and more particularly to a composite shadow mask member in which different materials are laminated.

[Conventional technology]

The shadow mask member has a large number of regularly arranged openings, and the electron beam emitted from the electron gun passes through these openings and irradiates the phosphor dots to reproduce a color image. It plays an extremely important role in dignity.

This shadow mask material is mainly required to have the following properties.

■The coefficient of thermal expansion is small.□Of the electron beam irradiated by the electron gun, less than 1/3 of the total passes through the opening, and the remaining electron beam collides with the shadow mask member without passing through. As a result, the shadow mask member is heated and thermally expanded, causing the opening to shift from its normal position, resulting in color shift in the color image. Therefore, the shadow mask member needs to be made of a low thermal expansion material, which is desirable.

This can be said to be the most basic required characteristic of a Yado mask member. 0 ■ Low yield strength □ Shadow mask members are molded into a specified shape by press processing, so good moldability is desired.

■The elastic modulus is large.□If the elastic modulus is small, the mask will be deformed during handling or use during the manufacturing of shadow masks and color cathode ray tubes, causing color misregistration.

However, although the mild steel conventionally used for shadow mask members satisfies the above characteristics in terms of yield strength and elastic modulus, it has a large coefficient of thermal expansion and is subject to significant color shift due to electron beam collisions. Ta.

In addition, attempts have been made to use an invar alloy with a small coefficient of thermal expansion, but this has poor press formability due to its high yield strength, and has a low elastic modulus, so it is usually 0.1 to 0.2 W.
There has been a problem in that it is extremely difficult to accurately maintain the shape of a shadow mask member having a high density of openings in a thin plate material of about 100 mL.

Recently, a shadow mask (4'! 157949/1983, 59861/1983, etc.) in which various alloying elements are added to a Fe-Ni based invar alloy for the purpose of improving strength has been disclosed, but the above-mentioned required characteristics are not met. The reality is that this has not yet been completely satisfied.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a shadow mask member that satisfies three characteristics required of a shadow mask member: (1) a low coefficient of thermal expansion, (2) a low yield strength, and (2) a large elastic modulus. It is something to do.

[Means for solving problems]

The present invention provides a shadow mask member with a 6-layer structure in which the inner layer is made of invar alloy and the outer layer sandwiching the inner layer is made of mild steel. ) is set to 0.15 to 0.5 to achieve the above object.

The specific numerical value of the characteristics of the shadow mask member according to the present invention is that the average coefficient of thermal expansion from 20°C to 100°C is 6. OX10
-'/'C or less 1 or less 1 numerosity coefficient 15,000 proboscis fj or more.

0.2% yield strength after annealing at 1000℃ for 1 hour is 23kf
f/*J or less, which satisfies the required characteristics as a shadow mask. In addition, in the shadow mask member of the present invention, it is desirable that the volumes of both outer layer parts sandwiching the inner layer part are equal to each other.

In addition, the thermal expansion coefficient and yield strength are 4 and OX 10, respectively.
It is more desirable to set it to -'/℃ or less and 20 kff/Ij or less.

[Effect]

Considering that the most basic requirement for shadow mask members is low thermal expansion as mentioned above,
In the present invention, an invar alloy is used to satisfy the requirements, while a mating material is soft steel in order to satisfy the requirements in terms of yield strength and elastic modulus.

When using a two-layer structure using Invar alloy and mild steel,
Warpage occurs during cold rolling due to the difference in mechanical strength between the two, making it impossible to put it into practical use as a shadow mask member that requires severe surface modification. Therefore, in the present invention, invar alloy is used for the inner layer and mild steel is used for the outer layer. It has a three-layer structure.

In the present invention, as described above, 6
The above object can be achieved by having a layered structure and by setting the ratio of the volume of the outer layer made of mild steel to the volume of the inner layer made of invar alloy to be 0.15 to 0.5. Specifically, such a shadow mask member has an average coefficient of thermal expansion of 6 at 20 to 100°C, and a coefficient of elasticity of 1 or less of OX 10-'/°C.
It has excellent properties such as 5,000 kff/mj or more and a 0,2 multi-yield strength of 23 kIlIf/J or less when annealed at 1000°C for 1 hour. (If the average coefficient of thermal expansion from 20 to 100℃ exceeds 6.oxlo-'/℃, it will not be effective in preventing color shift, and the elastic modulus will be 15,000kyf/w.
If it is less than J, the strength is insufficient and shadow mask deformation becomes a problem. Moreover, if the yield strength exceeds 23 kp/-, press formability tends to deteriorate. ) Outer layer volume to inner layer volume # (sum of both outer layer volumes)
When the ratio is less than 0.15, the elastic modulus decreases.

The yield strength tends to decrease, and when it exceeds 0.5, the thermal expansion coefficient increases, making it impossible to satisfy the required properties.

In addition, in the present invention, if the ratio is in the range of 0.15 to 0.5, the objective is achieved, but if the volumes of both outer layer parts are significantly different from each other, there is a problem that warpage occurs during cold rolling. Therefore, it is desirable that the volumes of both outer layers be equal.

〔Example〕

The present invention will be explained below based on examples.

The invar alloy and mild steel shown in Table 1 were each melted by a normal melting method, and shadow mask members having the volume ratios shown in Table 2 were obtained by hot rolling and cold rolling. In addition, both outer layer parts were made to have the same volume, and the total thickness was unified to 0.15 square meters.

Table 1 Table 2 These shadow mask members were measured for their average coefficient of thermal expansion from 20 to 100°C and 0.2 inch yield strength 2 modulus of elasticity after annealing at 1000°C for 1 hour. The results are also shown in Table 2.

In Table 2, the shadow mask members of the present invention with flatness 1 to JFL6 all have an average coefficient of thermal expansion of 6 and OXl 0''-'
/℃ or less, 0.2% proof stress is 23hf/J or less, and elastic modulus is 15,000ktif/Ij or more.

In other words, the strength of the shadow mask member of the present invention is dramatically improved compared to those using conventional invar alloys, and the average coefficient of thermal expansion at 20 to 100°C is less than one-third that of mild steel. It has excellent properties.

In this example, the Invar alloy shown in Table 1 was used, but the present invention is not limited to this, and it is also possible to use an Invar alloy to which the sixth component is added as necessary. Conceivable.

〔Effect of the invention〕

As mentioned above, the present invention has (1) a small coefficient of thermal expansion, which does not cause color shift, and (0) low proof stress, which makes press formability easy and easy, and (2) a high elastic modulus. Therefore, it satisfies the three characteristics that could not be simultaneously satisfied in the past, namely, that the shadow mask does not deform, and is very beneficial.

...Two-nee! −n'

Claims (3)

[Claims] (1) In a shadow mask member with a three-layer structure in which the inner layer is made of invar alloy and the outer layer sandwiching the inner layer is made of mild steel, the volume ratio of the outer layer to the inner layer is 0.15 to 0.5.
A shadow mask member characterized by: (2) Average thermal expansion coefficient between 20 and 100℃ is 6.0×10
^-^6/℃ or less, elastic modulus 15,000kg/mm^
2 or more, 0.2% proof stress annealed at 1000℃ for 1 hour is 23
The shadow mask member according to claim 1, which has a particle diameter of kgf/mm^2 or less. (3) The shadow mask member according to claim 1 or 2, wherein the volumes of both outer layer portions sandwiching the inner layer portion are equal to each other.