JPS61183846A - Shadow mask member - Google Patents

Abstract

PURPOSE:To inhibit the deformation of a shadow mask by making it by the use of a complex plate which is prepared by superimposing upon each other a thin plate having a low Young's modulus and a low thermal expansion coefficient and a thin plate having a high Young's modulus and a high thermal expansion coefficient. CONSTITUTION:First, a complex plate is formed by superimposing upon each other a thin plate (A) made of an Invar alloy composed of 25-50% Ni, Fe and unavoidable impurities and a thin plate (B) with a Young's modulus of at least 20,000kg/mm<2> made of a mile steel composed of at most 0.1% C, at most 0.5% Mn, at most 0.5% Si and Fe. Next, the thermal expansion coefficient and the Young's modulus of the complex plate are adjusted to at most 8.0X10<-6>/ deg.C and at least 15,000kg/mm<2> respectively, thereby making a shadow mask for a color cathode-ray tube. This shadow mask favorably has both a low thermal expansion coefficient and high physical strength which are opposite properties. Therefore, it is possible to effectually prevent any color nonuniformity of images.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shadow mask member used in a cathode ray tube of a color television.

[Conventional technology]

A shadow mask has many openings, and the electron beam emitted from the electron gun passes through these openings and irradiates the phosphor dots, thereby reproducing a color image. It plays a role. As the material of this shadow mask, mild steel is mainly used.

However, not all of the electron beam irradiated by the electron gun passes through the opening, and the shadow mask is heated by the electron beam that strikes the shadow mask without passing through. This heating causes thermal expansion of the shadow mask, and at the same time, the position of the opening is shifted, causing color shift in the color image.

To prevent this, for example, invar alloy (Ni36%,
A method has been adopted in which a bimetal made of stainless steel and the remaining Fe is used as a support spring for the shadow mask, and the shadow mask is moved closer to the phosphor surface by utilizing the curvature of the bimetal due to temperature changes to prevent color shift.

Furthermore, if the coefficient of thermal expansion of the shadow mask is sufficiently small, there is no need to employ a troublesome mechanism such as a support spring, so attempts have been made to form the shadow mask itself with an invar alloy having a small coefficient of thermal expansion.

However, invar alloy has low mechanical strength, specifically a low Young's modulus, so it is difficult to accurately maintain the shape of a shadow mask that has a high density of openings in a thin plate material of about 0.1 to 0.2 fl111. is extremely difficult and is an obstacle to practical application. In order to improve the strength, attempts have been made to increase the plate thickness as much as possible, but there is a problem that increasing the plate thickness makes it difficult to process high-density openings.

Furthermore, as a means to solve these problems,
In Publication No. 7949, C0,0 is added to 25 to 50% Ni.
Disclosed is a shadow mask formed of a material containing iron in an amount of 1% to 1%, with the remainder substantially consisting of iron.
It has been shown that the hardness is improved and the coefficient of thermal expansion is not significantly increased.

However, in this method, since the hardness is improved by adding C, there is a problem in the workability of the shadow mask itself. Further, the Young's modulus, which is the most important mechanical strength of a shadow mask, has not been improved.

[Problem that the invention seeks to solve]

As described above, conventional shadow masks have various problems, and it has become difficult to meet the image quality that has been increasingly demanded in recent years.

The present invention provides a shadow mask member that satisfies the contradictory characteristics of a low coefficient of thermal expansion and high mechanical strength, particularly Young's modulus, which are required for a shadow mask.

[Means for solving problems]

The present invention uses Ni25 to 50 as a shadow mask member.
% (weight %, the same applies in this specification), balance F
at least one PtfJ1 thin plate material made of e and unavoidable impurities, and a Young's modulus of 20.000 kg/
A small piece of steel with ma+2 or more (both 1 or more pieces! @
It is a composite body in which two thin plate materials are stacked alternately, and
Thermal expansion coefficient 8.0x10-6/℃ or less, Young's modulus 15,
The above-mentioned problem has been solved by using a material having a density of 000 kg/mm2 or more.

In other words, the required characteristics of a shadow mask are satisfied by alternately stacking thin plate materials with a low Young's modulus and a low thermal expansion coefficient and thin plate materials with a high Young's modulus and a high thermal expansion coefficient to form a composite. .

[For production]

In the first thin plate material, if Ni is less than 25%, low thermal expansion cannot be obtained, and if it exceeds 50%, low thermal expansion cannot be obtained and it becomes expensive.

Ni is desirably 30 to 43%.

The @2 thin plate material has a Young's modulus of 20 to maintain strength.
Any steel can be used as long as it is +000kg/ma+2 or more, but considering workability and economic efficiency, C001%
Below, Mn 0.5% or less, SiO, 5% or less, balance F
Generally referred to as mild steel, consisting of e and cine inevitable impurities, or C001% or less, C25% or less, Ni
It is preferable to use what is generally called stainless steel, which is composed of 10% or less, Mo 5% or less, W 5% or less, and the balance being Fe and unavoidable impurities.

A composite of the first thin plate material and the second thin plate material may have four or more layers, but considering the manufacturing process and other issues, a composite of two or three layers is preferable.

In addition, the thickness of each plate and the stacking arrangement in the case of three layers have a thermal expansion coefficient of 8°OX 10-6/
℃ or less and a Young's modulus of 15,000 kg/LI1m2 or more may be used.

The coefficient of thermal expansion is 8. If it exceeds OX 10-'/” (:
Not effective in preventing color shift, Young's modulus is 15°000
If the thermal expansion coefficient is less than 12 kg/mff, the strength will be insufficient and it will be difficult to maintain the shape of the shadow mask.The thermal expansion coefficient is preferably 6. OX 10-6/℃ or less, Young's modulus 16.000
kg/mm2 or more.

The object of the present invention is achieved through a synergistic effect when a thin plate material having a low Young's modulus but a low thermal expansion coefficient and a thin plate material having a high thermal expansion coefficient but a high Young's modulus are combined into a composite.

〔Example〕

The first thin plate material is Invar alloy A (Ni 36% balance Fe and inevitable impurities), and the tJS2 thin plate material is C0908%, Mn003%, S + 10-3%.
, the balance was Fe and unavoidable impurities.

(Example 1) The above Invar alloy A and mild steel B were combined to form a three-layer shadow mask member as shown in FIG. The plate thickness for both Invar alloy A and mild steel B is 0°05mm, and the overall plate thickness is 0.
．． It is 15mm.

(Example 2) The above Invar alloy A and mild steel B were combined to form a three-layer shadow mask member as shown in FIG. Invar alloy A has a plate thickness of 0.11m5. Mild steel B has a plate thickness of 0.02 mm, and the overall plate thickness is 0015 so- as in Example 1.

(Example 3) The above-mentioned Invar alloy A and mild steel B were combined to form a two-layer shadow mask member as shown in FIG. Invar alloy A has a plate thickness of 0.08III+1, and mild steel B has a plate thickness of 0.07
The overall plate thickness is also 0°15 mm.

Table 1 shows the thermal expansion coefficient and Young's modulus of the members of the present invention of Examples 1 to 3 and of the Invar alloy and mild steel having a plate thickness of 0.15 m+++ as a comparative material.

Table 1 As is clear from Table 1, according to this example, the coefficient of thermal expansion was kept low, the Young's modulus was improved, and the strength was also improved.

Considering that the thermal expansion coefficient of mild steel, which has been conventionally used as a shadow mask member, is 11.3×10-'/°C, the shadow mask member of this example has sufficient practicality. .

In this example, the case of a composite of invar alloy and mild steel has been described, but as mentioned above, the invention is not limited to this. Good results can also be obtained.

〔Effect of the invention〕

The shadow mask member of the present invention has an extremely small coefficient of thermal expansion compared to conventional mild steel, has sufficient strength as a shadow mask member, and is free from deformation.

Therefore, when using the shadow mask member of the present invention,
It is possible to widen the operating range of the conventional bimetal support spring, prevent color shift in color images, and provide stable images.

[Brief explanation of drawings]

1 to 3 are partial sectional views of a shadow mask member showing an embodiment of the present invention. A: 1st thin sheet material, B: 2nd thin sheet material agent Takashi Honma, patent attorney Figure 1 B: 2nd floor handling waste (soft damage) Figure 2 Figure 3

Claims (4)

[Claims] (1) At least one first thin plate material made of 25 to 50% Ni, balance Fe and unavoidable impurities, and at least one second thin plate material made of steel with a Young's modulus of 20,000 kg/mm^2 or more. It is a composite body in which these are alternately layered, and the coefficient of thermal expansion is 8.0 x 10^-^6/°C.
Hereinafter, a shadow mask member characterized by having a Young's modulus of 15,000 kg/mm^2 or more. (2) The composition of the second thin plate material is C0.1% or less, Mn0.
5% or less, Si 0.5% or less, the balance being Fe and unavoidable impurities. (3) The composition of the second thin plate material is C0.1% or less, Cr25
% or less, Ni 10% or less, Mo 5% or less, W 5% or less,
2. The shadow mask member according to claim 1, wherein the remainder consists of Fe and unavoidable impurities. (4) The shadow mask member according to any one of claims 1 to 3, wherein the composite has two or three layers.