JP2966415B2 - Shadow mask structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a shadow mask structure in which a shadow mask having a large number of holes formed in a thin metal plate is stretched over a frame under tension, and an oxide film is formed on the frame. About the method.

[Conventional technology]

The shadow mask used for color cathode-ray tubes has the function of selecting the color of the phosphor applied in a mosaic pattern on the phosphor screen, but it is thermally expanded and deformed due to the collision of the electron beam, impairing its function. Sometimes.

Conventionally, as a solution to this, as shown in JP-A-62-133645, for example, a shadow mask is stretched over a frame in a state where tension is applied to absorb elongation due to thermal expansion generated by collision of an electron beam. To prevent deformation.

And, this technique aims to prevent the tension from drastically lowering when the shadow mask to which tension is applied is heated to around 450 ° C. in the manufacturing process, for example, using amber for the shadow mask and Kovar for the frame, Tension relaxation is caused by the difference between the two thermal expansion characteristics.

[Problems to be solved by the invention]

The above-mentioned prior art uses Ni or Ni on the shadow mask and the frame.
Since an expensive material such as Co must be used, there is a problem that the cost is extremely high.

An object of the present invention is to provide a shadow mask structure that can be manufactured at low cost.

[Means for solving the problem]

The purpose is to use mild steel for the shadow mask and to make the frame have an average thermal expansion coefficient from room temperature to around 450 ° C (8 to 1).
3) Achieved by using a material of × 10 ^-6 / ° C.

The main composition of the frame material having the above characteristics is Fe and
Stainless steel containing 10 to 32 wt% of Cr is preferable because it is an inexpensive material having high mechanical strength.

When stainless steel having the above composition is used as the material of the frame, it is preferable to form an oxide film as a blackening treatment on the surface. The method of forming an oxide film on this frame is as follows:
Oxidizing mixed atmosphere, for example, in H ₂ O-H ₂ or CO ₂ -CO in 60
This is achieved by heat treatment at 0 to 900 ° C.

[Action]

When manufacturing color cathode ray tubes, the shadow mask is
Pass through the process above 400 ° C. At this time, in the case of a shadow mask to which tension has been applied in advance, for example, when the most common mild steel is used for the shadow mask and the frame, the yield strength is reduced at high temperatures, and a partial plastic deformation may occur.
Also, during cooling from a high temperature, due to the difference in heat capacity between the shadow mask and the frame, the shadow mask having a small heat capacity tends to decrease in temperature and shrink faster than the frame, which may also lead to plastic deformation. When they are cooled to room temperature, they appear in a form of reduced tension compared to before passing through a high temperature.

As a result of the experiment, it was found that when mild steel was used for the shadow mask, it is desirable that the average thermal expansion coefficient of the frame from room temperature to about 450 ° C. be (8 to 13) × 10 ⁻⁶ / ° C.

In addition to the thermal expansion coefficient, the requirements for mechanical strength, workability, weldability, price, etc. are added to the frame material. As a material that meets these requirements, stainless steel containing 10 to 32 wt% of Fe and Cr as the main components Is appropriate.

Preferably, the frame is subjected to a blackening process. If the blackening of the frame is insufficient, light may be reflected at the time of exposure in the step of applying graphite or a phosphor to the inner surface of the panel, and uneven exposure may occur. However, when stainless steel comprising the above components is used for the frame, it is extremely difficult to perform a blackening treatment for oxidizing the surface. The stainless steel is a heat-resistant material and has extremely high oxidation resistance. Therefore, an oxide film can be easily formed by providing fine irregularities on the surface of stainless steel.

As a method of forming an oxide film on the frame, H ₂ O-H
_When heat treatment is performed at 600 to 900 ° C. in an oxidizing mixed atmosphere of ₂ or CO ₂ —CO, H ₂ O—H ₂ or CO ₂ —CO becomes H ₂ OH ₂ +1/2
The O ₂ release in response to O _2, the reaction formula of _{CO 2 CO + 1 / 2O 2} , Cr
Stainless steel containing Fe ₂ O ₃ , Fe ₃ O ₄ , Fe
Of O, forming a layer of _{FeO · Cr 2 O 3, Cr} 2 O 3.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, the frame 1 is made of Cr18wt%
So-called ferritic stainless steel containing Fe and Fe as main components
SUS430, L-shaped cross section, 5m width at the top end of the cross section
m, width 10 mm at the lower end side, height 10 mm, overall size is 279 mm in outside diameter and 210 mm in length. The outer surface of the frame 1 is provided with fine irregularities of about 10 to 50 μm by sandblasting or the like, which is heated at 600 ° C. for 20 minutes in an oxidizing atmosphere, for example, CO ₂ —CO. An oxide film is formed on the surface. When the oxide film is formed in this manner, the reflection on the surface is significantly reduced. Generally, the reflectance is 1% or less with respect to the wavelength of light used at the time of exposure. A spring 2 having a pin hole 2a is fixed to the frame 1 thus formed.

The shadow mask 3 is made of mild steel plate and has a thickness of 0.025 mm.
The holes 3a having a hole diameter of 0.12 mm are arranged at intervals of about 0.26 mm on the entire surface except for the peripheral edge so that the mutual angle of the rows is 60 degrees. Then, in a state where tension is applied to the shadow mask 3, the periphery of the shadow mask 3 is welded over the entire circumference at a welded portion 1b shown by a two-dot chain line that connects substantially the center of the upper end 1a of the frame 1.

Next, a method for manufacturing such a shadow mask structure will be described with reference to FIG. First, the shadow mask 3 having the holes 3a formed therein as shown in FIG. 1 and having a larger size as shown in FIG. 1 is fixed flatly to the mask pulling frame 5 by welding 4 over the entire circumference. At this time, the shadow mask 3
Can be easily flattened by using a spring or a spring (not shown) and fixing it while pulling it lightly from the center to the outside. As the material of the mask pulling frame 5, SUS304 of austenitic stainless steel or the like is used.

The shadow mask 3 fixed flat on the mask pulling frame 5 in this manner is placed in a furnace and heated to 90 ° C. Thereafter, this is taken out of the furnace, and air 6 whose temperature has been adjusted to 30 ° C. is blown over the entire shadow mask 3, and only the shadow mask 3 is cooled to 30 ° C. At this time, since the shadow mask 3 is very thin, having a thickness of 0.025 mm, it is cooled to 30 ° C. in about 10 seconds. On the other hand, the temperature of the mask pulling frame 5 hardly drops because of its large heat capacity. Since the SUS304 used as the material of the mask pulling frame 5 has a coefficient of thermal expansion of about 17.3 × 10 ⁻⁶ / ° C., as described above, the shadow mask 3 contracted by decreasing the temperature by 60 ° C. from 90 ° C. to 30 ° C. Is applied uniformly with a tension of 20 kg / mm ² or more.

As described with reference to FIG. 1, the frame 1 on which the oxide film is formed is moved to a predetermined position under the shadow mask 3 in a state where the uniform tension is applied, and the frame 1 is moved and fixed to the base 7. Then, the shadow mask 3 and the frame 1 are fixed by welding 8 such as spot welding or seam welding over substantially the entire center of the upper end 1a of the frame 1 over the entire circumference. After welding, the shadow mask 3 is cut along the outer periphery of the frame 1. This work is a mask pulling frame 5
May be performed after cooling to room temperature.

Thereby, the shadow mask structure shown in FIG. 1 in which uniform tension is applied to the shadow mask 3 is completed. Then, as shown in FIG. 3, the shadow mask structure is inserted into the pin holes 2a of the springs 2 in the stud pins 10 embedded in the panel 9, and held and fixed inside the panel 9, and the subsequent processing is performed.

The shadow mask structure manufactured in this way does not decrease in tension even after passing through a heating step of 400 ° C or more in the process of manufacturing a cathode ray tube, and also has a problem when exposing graphite or phosphor. Absent.

Thus, since the shadow mask 3 is made of mild steel and the frame 1 is made of ferrite stainless steel SUS430, it can be manufactured at very low cost. The material of the frame 1 is not limited to SUS430, and the same effect can be obtained if the concentration of Cr is stainless steel of 10 to 32 wt%. When the stainless steel having the above composition contains less than 1 wt% of Ti, workability and weldability are improved. The frame 1 is not limited to stainless steel having the above composition, but may be any material having an average coefficient of thermal expansion from room temperature to about 450 ° C. (8 to 13) × 10 ⁻⁶ / ° C. Here, those having an average coefficient of thermal expansion of less than 8 × 10 ⁻⁶ / ° C. are not preferable because the shadow mask is easily broken at room temperature or lower. However, as for the material of the frame 1, in addition to the coefficient of thermal expansion, there are added requirements such as mechanical strength, workability, weldability, and price.
The above-mentioned stainless steel containing Fe and Cr in an amount of 10 to 32 wt% as a main component is most suitable.

Also, the shape of the frame 1 does not need to have an L-shaped cross section,
For example, it may be a complicated shape formed by press molding. Further, in the above embodiment, the tension is applied to the shadow mask 3 by using the mask pulling frame 5, but the present invention is not limited to this, and the tension may be applied by other tension applying means.

FIG. 4 shows a method for forming an oxide film on the frame 1 mainly containing Fe and Cr of 10 to 32 wt%. In the figure, the inside of a furnace 11 is heated by a heating element 12 comprising a high-frequency power source for 600 minutes.
It is kept at a temperature of ~ 900 ° C. H ₂ O−
A gas 13 of H ₂ or CO ₂ —CO is supplied to form an oxidizing mixed atmosphere.

Therefore, the frame 1 is moved by the roller conveyor 14 to the furnace 11.
When it is put into the inside, it is heated to 600 to 900 ° C. in an oxidizing atmosphere, and an oxide film of Fe ₂ O ₃ , Fe ₃ O ₄ , FeO—Cr ₂ O ₃ , and Cr ₂ O ₃ is sequentially formed on the surface.

By performing such treatment, an oxide film can be easily formed on stainless steel, which is an oxidation-resistant alloy. Here, the frame 1 does not need to have fine irregularities in advance, but if irregularities are imparted in the same manner as in the above-described embodiment,
An oxide film is more easily formed.

〔The invention's effect〕

According to the present invention, since the shadow mask is made of mild steel, it can be manufactured at low cost. The frame is made of Fe and Cr10 ~ 32wt
By using stainless steel containing% as a main component, the frame can be manufactured at low cost. Further, by providing fine irregularities on a frame made of stainless steel which is an oxidation-resistant alloy, an oxide film is easily formed. Also, as a method of forming an oxide film on the frame, 600
An oxide film can be formed on stainless steel, which is an oxidation-resistant alloy, by performing a heat treatment at about 900 ° C.

[Brief description of the drawings]

FIG. 1 is a perspective view of a shadow mask structure according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a method of manufacturing the shadow mask structure shown in FIG. 1, and FIG. 3 is a diagram illustrating the shadow mask of FIG. FIG. 4 is a sectional view showing a method of forming an oxide film on a frame. 1 ... frame, 2 ... spring, 3 ... shadow mask, 3a ... hole, 9 ... panel, 10 ... stud pin, 11 ... furnace, 12 ... heating element, 13 ... gas.

Continuation of the front page (72) Inventor Kumada Politics 3300 Hayano, Mobara-shi, Chiba Pref. JP-A-59-173244 (JP, A) JP-A-63-13240 (JP) JP-A-57-134847 (JP, A) JP-A-55-64333 (JP, A) JP-A-59-152556 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB Name) H01J 27/07 H01J 9/14 C23C 8/18 C23C 38/00

Claims (6)

(57) [Claims] A frame, a spring fixed to the frame and engaged with a stud pin embedded in a panel, and fixed to the frame in a state where tension is applied;
In a shadow mask assembly comprising a metal plate and a shadow mask having a large number of holes formed therein, the frame may be at room temperature to 45 mm.
Fe with an average coefficient of thermal expansion up to 0 ° C (8-13) × 10 ^-6 / ° C
A shadow mask structure comprising stainless steel containing Cr in an amount of 10 to 32 wt% as a main component, wherein the shadow mask is made of mild steel. 2. The stainless steel as the material of the frame,
2. The shadow mask structure according to claim 1, wherein the content of Ti is less than 1 wt%. 3. The frame according to claim 1, wherein said frame has an oxide film formed on a surface thereof.
The shadow mask structure according to any one of the preceding claims. 4. The shadow mask structure according to claim 1, wherein said frame has fine irregularities on the surface and an oxide film is formed on the surface. 5. The method according to claim 1, wherein said oxide film is made of Fe ₂ O ₃ , Fe ₃ O ₄ , FeO-CrO ₃ , Cr ₂ O ₃ from the surface of stainless steel which is a material of the frame. 5. The shadow mask structure according to claim 3 or 4, wherein 6. The shadow mask structure according to claim 4, wherein said unevenness is 10 to 50 μm.