JPS6282631A - Shadowmask member - Google Patents

Abstract

PURPOSE:To reduce the coefficient of thermal expansion of shadowmask thus to eliminate the color shift by employing such three layer structure as the inner layer composed of soft steel is held by the outer layer composed of invar alloy from the opposite sides while setting specific volume ratio between the inner and the outer layers. CONSTITUTION:A shadowmask member is formed with three layer structure where the soft steel inner layer is held by the invar alloy outer layer (Ni 36%, the remainder is Fe and the impurities) from the opposite sides. Here, the volume ratio of the inner layer against the outer layer is set to 0.15-0.5. The modulus of elasticity will deteriorate for the volume ratio lower than 0.15 to increase the durability 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 pressing performance is good because of limited durability and the mask will never deform because of high modulus of elasticity.

Description

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

[Conventional technology]

The shadow mask member has a large number of regularly arranged apertures, and the electron beam emitted from the electron gun passes through the apertures and is irradiated with a phosphor (drum) to reproduce a color image. It plays an extremely important role in image quality.

The following characteristics are mainly required for this shadow mask material.

■The coefficient of thermal expansion is small.□Of the electron beam irradiated by the electron gun, less than 1/6 of the total passes through the opening, and the remaining electron beam collides with the shadow mask member without passing through. Because the shadow mask is heated,
Thermal expansion causes the aperture to shift from its normal position, causing color shifts in the color image.To prevent this, the shadow mask member must be made of a low thermal expansion material, which is the most basic form of a shadow mask member. This can be said to be a required characteristic.

■Low yield strength□Shadow mask member Since it is formed into a specified shape by press processing, it is desired that it has good formability.

■Has a large elastic modulus□If the elastic modulus is small, mask deformation occurs during handling and use during shadow mask manufacturing and color cathode ray tube manufacturing, causing color shift. Although the mild steel used in this study satisfies the above-mentioned characteristics in terms of yield strength and elastic modulus, it has a large coefficient of thermal expansion and significant color shift due to electron beam collision.

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

Recently, a shadow mask (Unexamined Japanese Patent Publication No. 58-118), which is made by adding various alloying elements to Fe-Ni-based invar alloy for the purpose of improving strength, has been developed.
-157949, 59-59861, etc.), but the reality is that they do not completely satisfy the above-mentioned required characteristics.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a shadow mask member that satisfies six properties required of a shadow mask member, namely: ■ A low coefficient of thermal expansion; ■ A low yield strength; and ■ A large modulus of elasticity. It is something.

[Failure to solve the problem]

The present invention provides a shadow mask member with a six-layer structure in which the inner layer is made of mild steel and the outer layer sandwiching the inner layer is made of invar alloy. The above objective is achieved by setting the volume ratio to 0.15 to 0.5.

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 6.0X10/
'C or less 1 elastic modulus 15.000 and 9f/Q or more.

0.2% yield strength is 23 fe when annealed at 1000℃ for 1 hour
d 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 coefficient of thermal expansion and proof stress are 4.0X10-'/
It is more desirable to set the temperature to 20 kf/- or less.

[Effect]

Considering that low thermal expansion is the most basic requirement for shadow mask members as mentioned above, the present invention attempts to satisfy this requirement by using an invar alloy, while using an invar alloy as a counterpart material. Mild steel was used to satisfy the requirements in terms of yield strength and elastic modulus.

When creating a two-layer structure using Invar alloy and mild steel, warping occurs during cold rolling due to the difference in mechanical strength between the two.
Since this would not be suitable for practical use as a shadow mask member that requires strict surface precision, the present invention adopts a six-layer structure in which the inner layer is made of mild steel and the outer layer is made of invar alloy.

The present invention has a three-layer structure using an invar alloy and mild steel as described above, and the volume ratio of the inner layer made of mild steel to the outer layer made of invar alloy is 0.15 to 0.5. The above objective can be achieved. Specifically, the shadow mask member has an average coefficient of thermal expansion of 6.0 x 10''/4C or less at 20 to 100°C, and a modulus of elasticity of 15,00
The yield strength of 0 and 2 chips after annealing at 1000℃ for 1 hour is 23 for the 0 anus f layer and above? It has excellent characteristics of less than f/IJI. (The average thermal expansion coefficient from 20 to 100℃ is 6.0
If it exceeds X10-'/l, it will not be effective in preventing color misregistration, and if the elastic modulus is less than 15,000 mmf/J1, the shadow mask will deform immediately due to insufficient strength, and the yield strength will be 23 ki.
If it exceeds j, press formability tends to deteriorate. ) If the ratio of the inner layer volume to the outer shoulder volume (total volume of both outer layer parts) is less than 0.15, the elastic modulus will decrease and the yield strength will increase, and if it exceeds 0.5, the thermal expansion coefficient will increase, It becomes impossible to satisfy the required characteristics.

In addition, in the present invention, the objective can be achieved if the front ratio is in the range of 0.15 to 0.5, 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 preferable to make the volumes of both outer layer parts 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. The volumes of both outer layers were the same, and the total thickness was unified to 0.15 mm.

Table 1 Table 2 For these shadow mask members, the average coefficient of thermal expansion from 20 to 100°C and the 0.2 mm yield strength and elastic modulus after annealing at 1000°C for 1 hour were measured. The results are also shown in Table 2.

The shadow mask members of the present invention labeled 1 to 6 in Table 2 all have an average coefficient of thermal expansion of 6.0X10-', /'C or less 0
．． 2% proof stress is 23 Ume f/j or less 2 Elastic modulus is j5,00
0 to 9f/Ij or higher. 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 strength is 20 to 1
It has an excellent property that the average coefficient of thermal expansion at 00°C is less than one-third that of mild steel.

In this example, the Invar alloy shown in Table 1 was used, but the present invention is not limited to this, and it is of course possible to use an Invar alloy to which the sixth component is added, etc. It will be done.

〔Effect of the invention〕

Claims (3)

[Claims] (1) In a shadow mask member with a three-layer structure in which the inner layer is made of mild steel and the outer layer sandwiching the inner layer is made of invar alloy,
The ratio of the volume of the inner layer to the volume of the outer layer is 0.15 to 0.
5. A shadow mask member characterized in that: (2) The average coefficient of thermal expansion of the shadow mask member at 20 to 100°C is 6.0 x 10^-^6/°C or less, and the elastic modulus is 1.
The shadow mask member according to claim 1, which has a 0.2% yield strength of 5,000 kg/mm^2 or more and 23 kgf/mm^2 or less when annealed at 1000°C for 1 hour. (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.