JPH10199439A - Shadow mask and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a hole shape even if the material of a shadow mask is a thin plate, conduct sufficient plastic work at the same time, and obtain sufficient strength against the outside shock by compression the hole formed part of a shadow mask in the plate thickness direction and forming a plurality of recesses. SOLUTION: A flat mask in which many electron beam passing through holes 18 are formed is press-molded to obtain a shadow mask 6 having a predetermined shape. The inner surface of the hole formed part 20 of the shadow mask 6, or a recesses surface is compressed with a impact force applying device in the plate thickness direction, and a plurality of recesses 22 having a depth of 10-40μm are formed. The recess 22 formed by compression is a dented and hardened impression, and increases mechanical strength of the shadow mask 6. Even if the material of the shadow mask 6 is a thin plate, the strength of the shadow mask 6 is increased without damaging the shape of the electron beam passing through hole 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a shadow mask used for a color cathode ray tube and a method of manufacturing the same.

[0002]

2. Description of the Related Art Generally, a color cathode ray tube has a shadow mask functioning as a color selecting means. This shadow mask is formed by integrally processing a thin metal plate as a whole, and has a curved surface portion formed into a substantially spherical convex curved surface, and a substantially perpendicular to the curved surface portion and the entire periphery of the curved surface portion. And a skirt portion provided so as to surround it. Also,
The curved surface portion includes a perforated portion provided with a large number of electron beam passage holes, and a non-perforated peripheral portion located on the outer periphery of the perforated portion.

[0003] Such a shadow mask is usually formed by press-forming a flat mask in which electron beam transmission holes are formed in a flat thin metal plate. That is, first,
After annealing the flat mask to facilitate molding,
Press forming into a predetermined shape using a press mold. After press molding, a blackening process is performed to form an oxide film on the surface of the shadow mask, thereby completing the shadow mask.

[0004]

In recent years, the thickness of this shadow mask has been reduced to, for example, about 0.12 to 0.13 mm due to various embeddings. As a result, the strength of the shadow mask after press molding has been reduced. However, deformation due to external impact is a problem.

[0005] Conventional press molding is performed by using a mold (especially a punch) having a mirror-finished surface, and subjecting the mask material to stretching in the surface direction.
For this reason, stress concentration occurs at the perforated portion and the peripheral portion of the shadow mask, and the shape of the hole, which is referred to as elongation, is likely to be broken in the electron beam passage hole. Therefore, there is a limit on the amount of plastic working of the shadow mask.

[0006] For this reason, it is difficult to perform uniform processing over the entire surface of the perforated portion of the shadow mask.
As a result, a part of the shadow mask which is insufficiently processed is partially generated, and the shadow mask is partially slackened (commonly referred to as a side drop). In such a molded state, the entire shadow mask does not reach the plastic region, and the shape cannot be maintained when a drop impact is applied to the formed shadow mask. Such a phenomenon becomes more remarkable as the thickness of the shadow mask is smaller.

Although the above problem can be solved by increasing the thickness of the shadow mask, it is contrary to the tendency to reduce the thickness of the shadow mask. There is a problem that it becomes difficult to control the shape into a predetermined shape.

The present invention has been made in view of the above points, and an object of the present invention is to enable a sufficient plastic working to be performed while maintaining a hole shape even when a mask material is a thin plate, and to prevent an external impact. And to provide a shadow mask having a sufficient strength and a manufacturing method thereof.

[0009]

In order to achieve the above object, a shadow mask according to the present invention includes a curved portion formed by processing a thin metal plate and having a curved shape, and surrounding the entire circumference of the curved portion. And a skirt portion provided. The curved surface portion has a perforated portion provided with a large number of electron beam passage holes, and a non-perforated peripheral portion located on the outer periphery of the perforated portion. A plurality of recesses are formed on one surface of the perforated portion by being compressed in the thickness direction.

In the above shadow mask, each of the electron beam passing holes has a large hole opened on the convex curved surface side of the perforated portion, and a small hole opened on the concave curved surface side of the perforated portion.
The recess is formed in a concave curved surface of the perforated portion.

Further, the plurality of recesses extend radially from substantially the center of the perforated portion to the periphery of the perforated portion. Alternatively, the plurality of recesses are provided so as to be distributed over substantially the entire area of the perforated portion, and are each formed in a substantially hemispherical shape.

Further, in the method of manufacturing a shadow mask according to the present invention, a flat mask made of a thin metal plate having a perforated portion provided with a large number of electron beam passage holes is prepared.
The perforated portion of the flat mask is formed into a predetermined curved shape by performing a curved surface overhang by press working, and the perforated portion of the press-formed metal plate is compressed in the thickness direction thereof, and one of the perforated portions is formed. Are characterized by forming a plurality of recesses on the surface thereof.

In the step of forming the recess, the surface of the perforated portion where the small hole of the electron beam passage hole is opened is formed by locally compressing the surface. Further, in the method of manufacturing a shadow mask according to the present invention, a flat mask made of a thin metal plate having a perforated portion provided with a large number of electron beam passage holes is prepared, and the perforated portion of the flat mask is formed into a predetermined shape. Curved surface is formed by press working using a punch having a predetermined curved surface shape, and at the same time, the perforated portion of the metal plate is compressed in its thickness direction, and a plurality of concave portions are formed on one surface of the perforated portion. It is characterized by forming a place.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a color cathode ray tube having a shadow mask. The color cathode ray tube includes a vacuum envelope having a face panel 3 made of glass and a funnel 4 having a funnel shape. The face panel 3 includes a substantially rectangular effective portion 1,
Four side walls 2 erected along the periphery of the effective portion;
And the fennel 4 is connected to the side wall 2. At the center of the inner surface of each side wall 2, a stud pin 14 is provided so as to protrude inward.

On the inner surface of the effective portion 1, a phosphor screen 5 composed of phosphor layers of three colors emitting blue, green and red light is formed. A substantially rectangular shadow mask 6 is arranged inside the face panel 1 so as to face the phosphor screen 5. A shadow mask 6 having a color selection function is fixed to a rectangular mask frame 7, and the mask frame is supported by stud pins 14 via a plurality of elastic holders 15.

On the other hand, in the neck 7 of the funnel 4, 3
An electron gun 9 for emitting an electron beam 8 is provided. Then, the three electron beams 8 emitted from the electron gun 9 are deflected by the deflection yoke 24 mounted outside the funnel 4, and are deflected by the phosphor screen 5 through the shadow mask 6.
Is scanned horizontally and vertically. Thereby, a color image is displayed on the phosphor screen.

As shown in FIGS. 1 to 4B, the shadow mask 6 is formed integrally by processing a thin metal plate having a thickness of 0.10 to 0.15 mm, for example, and is formed into a convex curved surface. It has a curved surface portion 16 and a skirt portion 17 which is substantially perpendicular to the curved surface portion and is provided so as to surround the entire curved surface portion. The curved surface portion 16 includes a substantially rectangular perforated portion 20 provided with a large number of electron beam passage holes 18 and a non-perforated peripheral portion 21 located on the outer periphery of the perforated portion.

Each electron beam passage hole 18 has a large hole 18a opened on the outer surface of the curved surface portion 16, that is, on the side of the convex curved surface 16a.
And a small hole 18 opened on the concave curved surface 16b side of the curved surface portion 16
b. When the shadow mask 6 is mounted inside the vacuum envelope of the color cathode ray tube, the large holes 18a of the electron beams 18 face the phosphor screen 5,
The small hole 18b faces the electron gun 9.

As shown in FIGS. 3 and 4B, the inner surface of the perforated portion 20 of the shadow mask 6, that is, the concave curved surface 16b is formed by compressing the shadow mask in the thickness direction. A plurality of recesses 22 are provided.

In the present embodiment, these recesses 22
Are formed as a plurality of elongated grooves and extend radially from substantially the center of the perforated portion 20 to the periphery of the perforated portion. Each recess 2
The recess amount of No. 2 is formed to be about 10 μm.

Next, a method of manufacturing the shadow mask 6 configured as described above will be described. In the present manufacturing method, first, a flat mask having a plate shape in which a large number of electron beam passage holes 18 are formed is prepared, and the flat mask is annealed, and then press-molded into a predetermined shape. Then, the press-molded shadow mask is compressed in the thickness direction to form a plurality of recesses 22, and then blackened to form a blackened film on the shadow mask surface.

The press forming step will be described in detail. As shown in FIG. 5, the press device used for this press forming includes a punch 10, a knockout 11, a blank holder 12, and a die 13, which are pressed by a pressing device 26 and slide mechanisms 27, 28, 29 in the direction of arrow C. It is driven up and down along.

The lower surface of the punch 10 is formed into a convex curved surface 10a in which the shape of the curved surface portion 16 of the shadow mask to be molded is added with springback, and is mirror-finished. The knockout 11 has a concave surface 11a whose outer shape matches the outer shape of the punch 10 and only its annular peripheral portion is rubbed with the convex curved surface 10a of the punch 10 over the entire circumference.
Is formed. The blank holder 12 and the die 13 are respectively formed on curved surfaces in which annular peripheral portions 12a and 13a facing each other are rubbed together.

When performing press molding, first, as shown in FIG. 6A, the flat mask 30 is set on the peripheral portion 13a of the die 13. Next, as shown in FIG. 6B, the blank holder 12 is pushed down, and the skirt portion 30 a, which is to be the skirt portion 17, is moved to the peripheral edge 13 a of the die 13 and the peripheral edge 12 a of the blank holder 12. Between the two. Thereafter, as shown in FIG. 6C, the punch 10 is pressed down, and the flat mask 30 is pressed.
Is extended along the convex curved surface 10a of the punch 10,
The perforated part 20 and the peripheral part 21 following this are formed in a predetermined curved surface. Next, the non-porous peripheral portion 21 is firmly held between the peripheral portion of the convex curved surface 10 a of the punch 10 and the concave curved surface 11 a of the peripheral portion of the knockout 11.

Further, as shown in FIG. 6D, the pressing force applied to the blank holder 12 is relaxed, and the punch 10 is further pressed down by applying a stronger pressing force.
In this step, the punch 10 and the knockout 11 move downward while sandwiching the periphery of the flat mask 30,
It is pushed into the die 13. Thereby, the skirt part 1
7 is formed.

Finally, when the pressing force of the punch 10 and the blank holder 12 is released and the punch 10 is pulled upward, the press forming of the shadow mask 6 is completed. After the above-described press molding, the shadow mask 6 is subjected to compression processing. As shown in FIGS. 7 and 8, a mold 32 used for compression working includes a first working mold 34 having a convex curved surface 36,
A second processing die 38 having a concave curved surface 40. The first processing die 34 is formed to have substantially the same shape as the punch when the shadow mask is press-molded as a whole. The convex curved surface 36 of the first processing die 34 corresponds to the concave curved surface 16b of the curved surface portion 16 of the shadow mask 6, and the convex curved surface 36 has a plurality of elongated projections 4 extending radially.
2 are formed. The height of each projection 42 is 3 to 50 μm.
Is set to The concave curved surface 40 of the second processing die 38 is formed in a smooth shape corresponding to the convex curved surface 16a of the shadow mask curved surface portion 16, and has no projection.

The compression working process using the above mold 32 is as follows. First, as shown in FIG. 9A, the shadow mask 6 formed by pressing is placed on the convex curved surface 3 with the concave curved surface 16b thereof facing the convex curved surface 36 of the first processing die 34.
6. Place on top. Then, the second processing die 38 is placed on the shadow mask 6 with the concave curved surface 40 facing downward from above, and the first and second processing dies 34 and 38 sandwich the shadow mask.

Thereafter, as shown in FIG. 9 (b), an impact force F is applied to the second working die 38 from above toward the first working die 34 by an impact force applying device (not shown). When the impact force F is applied, the surface of the shadow mask 6 on the side of the convex curved surface 16a, that is, the surface on the side of the large hole 18a is concave concave surface 40 of the second processing die 38.
And no local stress is applied.

On the other hand, the concave curved surface 16b of the shadow mask 6,
That is, since the surface on the small hole side is in line contact with the protrusion 42 of the first processing die 34, a local stress is applied to the contact portion with the protrusion 42, and is compressed in the thickness direction of the shadow mask. As a result, a plurality of recesses 22 extending radially are formed on the inner surface of the perforated portion 20 of the shadow mask 6. In addition, the depth of the recess 22 is formed to be 10 to 40 μm.

As described above, in the present embodiment, the projections 42 are provided on the first processing die 34 located on the small hole 18b side of the shadow mask 6, for the following reason.

That is, the electron beam passage hole 18 of the shadow mask 6 is formed in the small hole 1 on the electron gun side of the color cathode ray tube.
8b is formed by connecting the large holes 18a on the phosphor screen side by etching, and the convex curved surface 16a in which the large holes 18a of the shadow mask 6 are formed.
Are more etched than the concave curved surface 16b where the small holes 18b are formed. Therefore, the surface on the side of the small hole, that is, the concave curved surface 16b of the curved surface portion 20 has a larger portion that remains without being etched, and the contact portion with the projection 42 can be increased.

Finally, the oxide film is formed on the surface of the shadow mask by performing blackening treatment in the same manner as in the prior art, thereby completing the shadow mask. According to the shadow mask 6 manufactured as described above, as described above, the surface 16b of the curved surface portion 16 on the side of the small hole 18b is indented by depression in the thickness direction and hardened, that is, an elongated shape. A groove-shaped recess 22 is formed. The mechanical strength of the shadow mask 6 is improved by forming the indentations by such compression processing. The thickness of the shadow mask is 0.12 m.
m, if the depression amount of the recess 22 is about 10 μm,
The strength can be improved without impairing the shape of the electron beam passage hole 18.

The shadow mask 6 manufactured by the above method
As a result of measuring the strength of the shadow mask, even when the conventional shadow mask was subjected to an external impact that had been deformed, the shadow mask was not deformed and could withstand a larger impact. Further, according to the present manufacturing method, it is possible to form even a shadow mask having a thickness that is difficult to form due to insufficient strength after press forming by the conventional manufacturing method.

In the above manufacturing method, since the shadow mask is subjected to compression in the thickness direction after press molding, there is an advantage that the press molding itself can use the same apparatus as before.

In the above-described embodiment, the impact is applied from the side of the second working die with the first working die down, but a method of disposing the second working die downward may be used. .
In addition, indentations provided on the small hole side surface of the shadow mask,
That is, the recess 22 is not limited to the above-described elongated groove shape, and can be variously changed as needed. For example, as shown in FIG. 10, the recess 22 may have a substantially hemispherical shape.

As shown in FIGS. 11 to 12B, the mold 32 used for manufacturing such a shadow mask 6 includes first and second working dies 34 and 38. A large number of metal spheres, for example, steel balls having a diameter of 4 mm, are densely embedded almost over the entire surface of the convex curved surface 36 to form a large number of substantially hemispherical projections 42. And projection 4
The convex curved surface formed by connecting the tops of the two corresponds to the concave curved surface 16b of the curved surface portion 16 of the shadow mask 6. In addition, the concave curved surface 40 of the second processing die 38 has a smooth shape corresponding to the convex curved surface 16a of the curved surface portion 16 of the shadow mask, and has no metal spheres embedded therein and no projection on the surface.

Then, the shadow mask 6 is press-formed in the same manner as described above, and then is compressed using the mold 32. With such a shadow mask and its manufacturing method, the same operation and effect as those of the above-described embodiment can be obtained.

Further, in the above-described embodiment, after the curved surface is formed by the press, the compression process is performed by using the mold 32. However, a projection is provided on the punch surface of the press device, and the curved surface is formed by the press and the metal surface is formed. The compression working in the thickness direction of the board may be performed simultaneously.

That is, in this case, the convex curved surface 10a of the punch 10 of the press device shown in FIG. 5 is not made a mirror surface, and the convex curved surface 10a is provided with a projection 42 as shown in FIG. 8 or FIG. 12 (b). Alternatively, as shown in FIG. 13, the convex curved surface 10a of the punch 10 is not mirror-finished, but the machining trace 46 by cutting is left as it is, so that the protrusion of about 3 to 50 μm formed by the mechanical trace is regularly formed on the convex curved surface. It may be formed in a targeted or random manner to have fine irregularities.

When the shadow mask 6 is formed by using the punch 10, first, the flat mask 30 is set on the peripheral portion 13 a of the die 13, similarly to the steps shown in FIGS. 6A to 6 D. I do. Next, the blank holder 12 is pushed down in the direction of arrow C, and the skirt portion 30 a, which is to become the skirt portion 17, is sandwiched between the peripheral portion 13 a of the die 13 and the peripheral portion 12 a of the blank holder 12.

Thereafter, the punch 10 is pushed down to extend the flat mask 30 along the convex curved surface 10a of the punch 10 to form the perforated portion 20 and the peripheral portion 21 following the perforated portion 20 into a predetermined curved surface. At the same time, the flat mask 30 is compressed in the thickness direction by the irregularities of the convex
Form 2

Next, the non-perforated peripheral portion 21 is firmly clamped between the peripheral portion of the convex curved surface 10a of the punch 10 and the concave curved surface 11a of the peripheral portion of the knockout 11. Further, the pressing force applied to the blank holder 12 is loosened, and a stronger pressing force is applied to the punch 10 to push the punch 10 downward.
In this step, the punch 10 and the knockout 11 move downward while sandwiching the periphery of the flat mask 30,
It is pushed into the die 13. Thereby, the skirt part 1
7 is formed.

Finally, when the pressing force of the punch 10 and the blank holder 12 is released and the punch 10 is pulled up, the press forming and the compressing of the shadow mask 6 are completed. Thereafter, the shadow mask is completed by performing blackening treatment to form an oxide film on the surface of the shadow mask.

In the case where the above-described manufacturing method is used, as in the above-described embodiment, even if the mask material is a thin plate, sufficient plastic working is performed while maintaining the shape of the electron beam passage hole. Thus, a shadow mask having sufficient mechanical strength against external impact can be obtained. In addition, it is not necessary to mirror-finish the convex curved surface of the punch, and it is possible to reduce the mold manufacturing cost.

[0045]

As described above in detail, according to the present invention, even if the mask material is a thin plate, sufficient plastic working can be performed while maintaining the shape of the hole, and sufficient resistance to external impact can be obtained. A shadow mask having a high strength and a method for manufacturing the same can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a color cathode ray tube having a shadow mask according to an embodiment of the present invention.

FIG. 2 is a perspective view of the shadow mask.

FIG. 3 is a plan view showing an inner surface side of the shadow mask.

4A is a cross-sectional view taken along a line AA in FIG. 3, and FIG. 4B is an enlarged cross-sectional view of a portion B in FIG. 4A.

FIG. 5 is a cross-sectional view of a press device used for manufacturing the shadow mask.

FIG. 6 is a cross-sectional view schematically showing a shadow mask press molding process using the above press apparatus.

FIG. 7 is a sectional view of a mold used for compression processing of the shadow mask.

FIG. 8 is a perspective view showing a first processing die of the die.

FIG. 9 is a cross-sectional view schematically showing a compression processing step of the shadow mask using the mold.

FIG. 10 is an enlarged sectional view showing a part of a shadow mask according to another embodiment of the present invention.

FIG. 11 is a cross-sectional view of a mold used for compressing a shadow mask according to another embodiment.

FIG. 12 is a perspective view showing a first processing die of the die shown in FIG. 11;

FIG. 13 is a perspective view showing a modified example of the punch used in the press device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Face panel 6 ... Shadow mask 9 ... Electron gun 10 ... Punch 10a ... Convex surface 16 ... Curved surface part 17 ... Skirt part 18 ... Electron beam passage hole 18a ... Large hole 18b ... Small hole 20 ... Perforated part 21 ... Peripheral part 22 ... recess 30 ... flat mask 32 ... mold 34 ... first mold 36 ... convex curved surface 38 ... second mold 40 ... concave curved surface 42 ... protrusion

Claims (15)

[Claims] 1. A curved surface portion formed by processing a thin metal plate and having a curved shape, and a skirt portion provided around the entire circumference of the curved surface portion, wherein the curved surface portion includes a large number of electron beams. It has a perforated portion provided with a through-hole, and a non-perforated peripheral portion located on the outer periphery of the perforated portion. The perforated portion is formed by compressing the perforated portion in the thickness direction. A shadow mask comprising a plurality of recesses formed on one surface of a portion. 2. Each of the electron beam passage holes has a large hole opened on the convex curved surface side of the perforated portion, and a small hole opened on the concave curved surface side of the perforated portion. The shadow mask according to claim 1, wherein the shadow mask is formed on a concave curved surface of the perforated portion. 3. The shadow mask according to claim 1, wherein the plurality of recesses extend radially from substantially the center of the perforated portion to the periphery of the perforated portion. 4. The shadow mask according to claim 1, wherein the plurality of recesses are provided in a substantially entire area of the perforated portion, and are each formed in a substantially hemispherical shape. . 5. The metal plate has a thickness of 0.10 to 0.15 mm,
The shadow mask according to claim 1, wherein each of the recesses has a depth of 3 to 50 μm. 6. A flat mask made of a thin metal plate having a perforated portion provided with a large number of electron beam passage holes is provided, and the perforated portion of the flat mask is subjected to a curved surface overhang by press working to obtain a predetermined curved surface. Formed into a shape, compressing the perforated part of the press-formed metal plate in its thickness direction,
A method of manufacturing a shadow mask, comprising forming a plurality of recesses on one surface of the perforated portion. 7. The method according to claim 1, wherein the step of forming the recess is performed by locally compressing the surface of the perforated portion where the small hole of the electron beam passage hole is opened. Item 6
3. The method for manufacturing a shadow mask according to 1., 8. The step of forming the concave portion includes a convex curved surface facing the concave curved surface of the perforated portion in which the small hole of the electron beam passage hole is opened, and a plurality of protrusions provided on the convex curved surface. The press-formed metal plate is interposed between a first mold and a second mold having a smooth concave curved surface facing the convex curved surface of the perforated portion where the large hole of the electron beam passage hole is opened. The method for manufacturing a shadow mask according to claim 6, wherein the hole is sandwiched and compression processing is performed. 9. The plurality of projections of the first type are constituted by a plurality of elongated projections extending radially, and the projections radially extend from the center of the aperture to the periphery of the aperture. 9. The method according to claim 8, wherein a plurality of recesses extending in a direction are formed. 10. The shadow mask according to claim 8, wherein the first type projections are constituted by a large number of substantially hemispherical projections provided over the entire convex curved surface. Production method. 11. A perforated portion of the flat mask is press-formed by press working using a punch having a shape corresponding to the curved surface shape of the perforated portion, and a plurality of projections are formed on the surface in substantially the same shape as the punch. The press-formed hole is sandwiched between a first mold provided and a second mold having a curved shape corresponding to the hole, and compression processing is performed. 7. The method for manufacturing a shadow mask according to item 6. 12. A flat mask made of a thin metal plate having a perforated portion provided with a large number of electron beam passage holes is prepared, and the perforated portion of the flat mask is pressed by using a punch having a predetermined shape. Forming a predetermined curved surface shape by performing a curved surface overhang, simultaneously compressing the perforated portion of the metal plate in the thickness direction thereof, forming a plurality of recesses on one surface of the perforated portion. Shadow mask manufacturing method. 13. The concave portion is formed by locally compressing one surface of the effective portion by a plurality of projections provided on the surface of the punch.
3. The method for manufacturing a shadow mask according to 1., 14. A height 3 to 3 provided on the surface of the punch.
13. The shadow mask according to claim 12, wherein one surface of the effective portion having a thickness of 0.10 to 0.15 mm is locally compressed by a plurality of protrusions of 50 μm to form the recess. Production method. 15. The concave portion is formed by compressing one surface of the effective portion with a punch having a surface having irregularities formed by machining marks.
3. The method for manufacturing a shadow mask according to item 2.