JPS5932859B2 - Shadow mask and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a shadow mask for television and a method for manufacturing the same.

[Technical background of the invention and its problems]

A shadow mask tube is a picture tube that has been widely used as a color television picture tube.

As shown in perspective in FIG. 1, this shadow mask tube has a shadow mask 1 having a large number of electron beam passage holes, and a three-color fluorescent surface 2 formed corresponding to each electron beam passage hole. The color is selected based on the incident angle of each of the three electron beams from the electron gun 3 that enter the electron beam passage hole. The shape of the electron beam passage hole is such as to avoid the generation of scattered electrons, as shown in cross section in FIG. 2, for example.

However, with the photo-etching method currently used to form electron beam passage holes, it is difficult to form electron beam passage holes uniformly and accurately as shown in Figure 2, and it is easy to cause a decrease in color purity called a doming phenomenon. There was a drawback. Particularly recently, the general demand for "fine detail" on television screens has increased, and the transmission method is being changed to a method called a high-definition television method. Correspondingly, it is desired that the performance of picture tubes be further improved so that they can reproduce clear and fine-grained images without the doming phenomenon. Therefore, there is an urgent need to develop a shadow mask with a high density and high precision electron beam passage hole and a small pitch. Furthermore, the cause of the doming phenomenon is that 80 to 85% of the electron beam generated from the electron gun impinges on the shadow mask, causing the shadow mask to thermally expand due to the temperature rise.
Another drawback was that the relative positional relationship between the electron beam passage hole and the phosphor mosaic on the electron beam trajectory changed, resulting in a doming phenomenon.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a shadow mask and a method for manufacturing the same, which can provide a picture tube in which electron beam passing holes are provided in a shadow mask with high density and high precision and do not cause doming. Furthermore, by selecting a shadow mask material, it is possible to suppress thermal expansion due to electron beam impact and obtain a high performance product.

[Summary of the invention]

The present invention provides a method for manufacturing a shadow mask in which at least 35% of {100} crystal planes are aggregated on the surface facing the fluorescent surface of the shadow mask, and an electron beam passing hole is formed by etching, after forging the shadow mask material. a step of performing hot rolling so that {100} crystal planes gather on the rolling surface, and a step of performing cold rolling and heat treatment to obtain a shadow mask original sheet, and a step of performing cold rolling and heat treatment, and the step of obtaining a shadow mask original sheet, {100}
This method of manufacturing a shadow mask includes a step of etching the crystal plane side to form an electron beam passage hole.

In other words, the present invention provides high-density and high-precision etching when forming electron beam passing holes in a shadow mask by photo-etching. This provides an electron beam passage hole.

More specifically, when forming electron beam passage holes in a shadow mask by photo-etching, in order to make the size and shape fine and uniform over the entire surface, the etching speed must be constant over the entire surface of the shadow mask. This is achieved by defining the crystal plane of the etching surface. In other words, if the crystal grains on the etched surface are irregular and the directions of the {100} crystal planes are different, the etching speed will be different between the crystal grains that are easily etched and the crystal grains that are difficult to etch, resulting in fine electron beam passage holes. It becomes difficult to obtain with high density and high precision. Therefore, the shadow mask according to the present invention has 35% or more of {100} crystal planes gathered on the surface facing the fluorescent surface, that is, the surface to be etched.

A shadow mask in which the electron beam passing holes are controlled with high accuracy and density can be obtained by concentrating 35% or more of {100} crystal planes, but it is more preferable to use {100} crystal planes.
00} It is desirable to aggregate 40% or more of the crystal faces. Here, the degree to which {100} crystal planes are gathered on the surface facing the fluorescent surface (hereinafter referred to as "mask surface") is defined as follows.

That is, the component of the {100} crystal axis direction of each polycrystalline grain in the direction perpendicular to the mask surface is defined as the following amount, which is the summed ratio for all crystallinities. ″ Here, Vφ is the grain volume ratio, and φ is the direction perpendicular to the mask surface and {1
00} is the angle formed with the crystal axis.

Further, the manufacturing method according to the present invention is a manufacturing method in which the etched plane is aligned with the {100} crystal plane as described above.

First, after forging the shadow mask material, {100} crystal planes are gathered on the rolled surface in a step of hot rolling, which is preferably the main thickness reduction step. Next, cold working at a rolling rate of 50% or less and heat treatment are repeated multiple times as necessary to form a shadow mask original plate. The reason why the cold working is performed at a rolling rate of 50% or less per time is to prevent the crystal direction of the rolled surface from being deviated from the {100} plane when strong working is performed. Further, the rolling ratio during the above-mentioned cold rolling is preferably set to 10% to 30% in practical terms. As described above, it is preferable to use a face-centered cubic lattice structure or a body-centered cubic lattice structure as the shadow mask material used in the present invention in order to align the crystal planes, and in practical use, an invar type alloy is used. This Invar alloy is one that hardly expands despite the temperature rise due to the impact of electron beams, so long as it has a coefficient of thermal expansion close to zero. Specifically, Invar alloy (3
6-SNp-63.5Fe), ultra-constant steel (32Ni-5
C0-63Fe), stainless steel (54C0-9.
3Cr-36.5Fe), 43Pd-57Fe alloy, etc. can be used. Further, in the present invention, the heat treatment performed after the cold rolling is performed to perform strain relief annealing to stabilize the {100} crystal plane.

In addition, in the process of obtaining a shadow mask original plate by performing predetermined cold rolling and heat treatment, for example, a rolling rate of 50% or less/
After one cold rolling is performed multiple times, the final heat treatment may be performed, or the operation of performing the heat treatment after each cold rolling may be repeated multiple times. [Embodiments of the Invention] Example 1 An Invar alloy having a composition of 36% Ni-Fe was melted, and the ingot was made into a wire rod with a diameter of 6 mm through a continuous hot wire making process.

This wire rod is forged at right angles to the longitudinal direction, and has a thickness of 1mm and a width of 1mm.
The plate body had a cross section of 00 mm. Next, after hot rolling at 900°C to a thickness of 0.5 mm, a thin plate of 0.3571 tm thickness and 286 mm width was obtained by cold rolling at a rolling rate of 30%, which was wound into a roll and heated in a vacuum for heat treatment. 55'C, strain annealing was performed for 2 hours. Furthermore, this thin plate was cold rolled at a rolling ratio of 30% to a thickness of 0.245, 408
After it was made into a thin plate with a wide width, it was similarly subjected to strain relief annealing.
Such cold rolling and heat treatment operations were repeated several times, and the result was 0.17! T7! A shadow mask original plate having a thickness of L and a width of 1000 mm was obtained. In addition, when examining the surface condition after hot rolling in the above process by X-ray diffraction, it was found that 40% of {100} crystal faces were aggregated, and even after subsequent cold rolling and heat treatment, stable {100} crystals remained. The surface was maintained.

Next, as a comparative example, a shadow mask original plate having a surface in which {100} crystal planes are assembled by the method described above was subjected to the same hot rolling, and then cold rolling and heat treatment at a rolling rate of 80% once. A comparison was made between the shadow masks that were subjected to etching treatment to provide electron beam passage holes.

For example, using an aqueous solution of 6% ferrous chloride and 0.1% hydrochloric acid,
65℃ using an aqueous solution of 6% ferrous chloride and 0.1% hydrochloric acid,
Etching was performed at a temperature of 65° C. to provide electron beam passage holes. Note that the electron beam passage holes were formed into the shape shown in FIG. 2 by sequentially photoetching on both sides of the shadow mask original plate.

The pinch of the electron beam passing holes was about 0.3 mm, and about 520,000 electron beam passing holes were formed as a shadow mask for a 14-inch television. The electron beam passing holes on the surface of the shadow mask at this time were examined, and a partially enlarged plan view of the mask according to the above-mentioned Example-1 is shown in FIG. 3, and a partially enlarged plan view of the mask according to the above-mentioned Comparative Example is shown in FIG. Note that 9 in the figure indicates an electron beam passage hole. As is clear from these results, it is clear that electron beam passing holes are formed uniformly and with high precision in the shadow mask according to the present invention.

Example 2 In Example-1 above, the rolling rate at one time during cold rolling was set to 2.
A shadow mask in which 42% of {100} crystal planes were assembled was manufactured in the same manner as above.

As a result, the same results as in Example-1 could be obtained.
Example 3 Forging and hot rolling were performed in the same manner as in Example-1 above, and 0
．． After obtaining a thin plate with a thickness of 5 mm and a width of 2007 nm, cold rolling is repeated multiple times at a rolling rate of about 8%.
Using the zero stage roll method, 0.1mm thickness, 1000m7!
A shadow mask original plate was obtained in which 43% of {100} crystal planes were assembled in L width.

Next, after applying strain relief annealing at 550℃ for 2 hours,
Photoetching was performed in the same manner as in Example-1.

As a result, it was possible to obtain a highly accurate and uniform electron beam passage hole as shown in FIG. [Effects of the Invention] As is clear from the above results, by using the manufacturing method of the present invention, it is possible to obtain a shadow mask original plate in which {100} crystal planes are assembled on the surface. Holes can be provided uniformly with high density and precision.

As a result, the width has been reduced by approximately 1 compared to conventional shadow masks.
/3, the number of electron beam passing holes can be increased to about 5 times, and high quality products without doming phenomena can be obtained. Furthermore, in the present invention, the doming phenomenon caused by thermal expansion can also be improved by selecting a shadow mask material.

[Brief explanation of drawings]

FIG. 1 is a needle perspective view showing the principle of a shadow mask tube, FIG. 2 is a sectional view showing an example of the shape of an electron beam passage hole, FIG. 3 is a partially enlarged plan view showing a shadow mask according to the present invention, and FIG.
The figure is a partially enlarged plan view showing a conventional shadow mask. 1...Shadow mask, 9...Electron beam passage hole.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a shadow mask in which an electron beam passage hole is formed by etching, including a step of forging a shadow mask material and then hot rolling it so that {100} crystal planes gather on the rolled surface; a step of cold rolling and heat treatment not exceeding 50%/time to obtain a shadow mask original plate, and a step of etching the {100} crystal plane side of the shadow mask original plate to form an electron beam passage hole. A method for manufacturing a shadow mask characterized by: 2. A shadow mask characterized in that 35% or more of {100} crystal planes are aggregated at least on the surface facing the fluorescent surface of the shadow mask. 3. A shadow mask according to claim 2, characterized in that the shadow mask is made of an alloy having a face-centered cubic lattice structure and a body-centered cubic lattice structure. 4. A shadow mask according to claim 2, characterized in that the shadow mask is made of an Invar alloy.