JPH09199015A - Method for surface treatment of support frame for shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for surface treatment of support frame for shadow mask, which can form an oxide film having the equal characteristic with a photographic film and which can eliminate the photographic film so as to simplify the work, in a support frame made of the stainless steel material. SOLUTION: An oxide film of Cr2 O3 is produced on the surface of a support frame 1 in annealing for improvement of the magnetic characteristic of a color cathode-ray tube. For example, in annealing for elimination of the distortion due to the working in pressing the support frame 1 and for lowering of the concentration of the contained carbon, the mixture gas of H2 +N2 , in which a small quantity of moisture is contained, is supplied into an annealing surface so as to produce the oxide film of Cr2 O3 on the surface of the support frame 1. This support frame 1, to which the surface treatment is performed, is welded to a shadow mask 2 and a spring 3 for assembling, and assembled as a shadow mask structure in a color cathode-ray tube. A color deflection error of the shadow mask 2 is thereby reduce so as to obtain the image of high quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for a support frame which is a member of a shadow mask structure of a color cathode ray tube.

[0002]

2. Description of the Related Art In general, a support frame is made of iron material, and a blackening treatment (Fe ₂ O ₃ ) is applied to the surface of the material in order to avoid the influences of the manufacturing process of the color cathode ray tube, the oxidation in the tube, and the heat radiation characteristics. I am doing it. By the way, in recent years, a stainless steel support frame has been adopted in order to improve the doming characteristics, and the stainless steel support frame is also subjected to blackening treatment with the same specifications as the conventional iron support frame.

[0003]

In the iron support frame, 99% of the components are iron, and the blackening treatment (Fe ₂ O ₃ )
Is easy. However, the stainless steel support frame is composed of 86% of iron and other components such as Cr and Mn.
The conventional blackening treatment cannot produce a sufficient oxide film.

An object of the present invention is to provide a shadow mask for a support frame made of stainless steel, which can form an oxide film having characteristics equivalent to those of a blackening film and can eliminate the blackening process to simplify the work. It is to provide a surface treatment method for a support frame.

[0005]

The first means of the present invention for solving the above-mentioned problems is to provide a surface treatment method for a support frame made of a stainless material, in which the surface of the support frame is annealed during the annealing treatment of the support frame. C
It is characterized by forming an oxide film of r ₂ O ₃ .

A second means of the present invention for solving the above-mentioned problems is to provide a surface treatment method for a support frame made of a stainless steel material, wherein H ₂ + N ₂ containing a small amount of water is added when the support frame is annealed. The mixed gas was supplied into the annealing furnace to deposit Cr _{2 on} the surface of the support frame.
It is characterized by producing an oxide film of O ₃ .

A third means of the present invention for solving the above-mentioned problems is the second means, wherein the water content is Dp =
The temperature is 17 to 25 ° C.

The fourth means of the present invention for solving the above-mentioned problems is characterized in that, in the second means, the temperature in the annealing furnace is 800 to 900 ° C.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Among color cathode ray tubes, a color display tube needs to have a high image quality, and a support frame has a low expansion in order to reduce an electron beam landing error (color misregistration) due to doming of a shadow mask. The stainless steel material that is now used. However, the landing error due to the influence of geomagnetism also has a high influence on the quality, and as a solution to this problem, annealing is performed to remove the processing strain during press molding of the support frame or to reduce the carbon content in the material. . In this annealing process, an H ₂ + N ₂ gas atmosphere furnace is used.

In this embodiment, when this annealing process is performed, a small amount of water having a Dp (due point) of 17 to 25 ° C. is included in the mixed gas of H ₂ + N _{2 and} the temperature inside the furnace is set to 8
It was supplied into the annealing furnace at 00 to 900 ° C. As a method of making the mixed gas contain water, the mixed gas of H ₂ + N ₂ is made to contain water, or the H ₂ gas and the N ₂ gas are made to contain water respectively, and then the two gases are mixed.

FIG. 1 shows the component distribution of the stainless steel support frame by laser Raman analysis. FIG. 1 is before the annealing treatment, FIG. 2 is after the annealing treatment according to the present embodiment, and FIG. 3 is after the annealing treatment according to the present embodiment. The results of further blackening processing are shown. In the figure, the horizontal axis is the wave number (cm
^-1 ), the vertical axis shows the peak intensity. The measurement content specifies the chemical species present by measuring the Raman light generated by irradiating the material surface with laser light. The peak value represents the ratio of the peak intensity of the detected chemical element to the plasma line.

As is clear from comparing FIGS. 1 and 2,
Cr precipitated from the grain boundaries on the surface of the stainless steel treated at high temperature reacted with O _{2 in} the water of the mixed gas containing water, and the peak intensity ratio of the black Cr ₂ O ₃ coating was greatly increased. . If Dp is small, the effect of oxidation is weakened. As a result of the experiment, favorable results were obtained in the range of Dp = 17 to 25 ° C.

Further, as is clear from comparison between FIG. 2 and FIG. 3, even if the blackening treatment is further performed, Cr ₂ O ₃ in the blackening treatment furnace is increased.
The effect of film formation is very small. That is, after reducing the impurities on the surface of the material only by annealing,
It is possible to form an oxide film similar to the blackening film by reacting with ₂ under the above-mentioned conditions, and the blackening treatment can be performed instead.

FIG. 4 shows the shadow mask structure. That is,
The support frame 1 processed by the above-described method is assembled by welding the shadow mask 2 and the spring 3 and assembled as a shadow mask structure into a color cathode ray tube or a color display tube.

[0015]

According to the present invention, when the support frame is annealed for removing molding strain, a black oxide film is simultaneously formed and a surface treatment having the same effect as the blackening treatment is performed. The chemical treatment process can be omitted, and the work can be simplified.

[Brief description of drawings]

FIG. 1 is a diagram showing a component distribution on a surface of a stainless steel support frame before annealing treatment.

FIG. 2 is a diagram showing a component distribution on a surface of a stainless steel support frame after an annealing treatment according to an embodiment of the present invention.

FIG. 3 is a diagram showing the component distribution on the surface of the stainless steel support frame that has been further blackened after the annealing treatment according to the present embodiment.

FIG. 4 is a side view of a shadow mask structure.

[Explanation of symbols]

 1 Support frame

Claims (4)

[Claims] 1. A surface treatment method for a support frame made of a stainless steel material, wherein a Cr ₂ O ₃ oxide film is formed on the surface of the support frame during the annealing treatment of the support frame. Surface treatment method. 2. A surface treatment method for a support frame made of a stainless steel material, wherein a H ₂ + N ₂ mixed gas containing a small amount of water is supplied into an annealing furnace during the annealing treatment of the support frame. A surface treatment method for a support frame for a shadow mask, characterized in that a Cr ₂ O ₃ oxide film is formed on the surface. 3. The surface treatment method for a shadow mask support frame according to claim 2, wherein the water content is Dp = 17 to 25 ° C. 4. The temperature in the annealing furnace is 800 to 9
The surface treatment method for a shadow mask support frame according to claim 2, wherein the temperature is 00 ° C.