JPH0536359A - Shadow mask for color picture tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the rigidity of a flat type shadow mask with a large radius of curvature by making the curvature of the effective region of a front wall smaller than the curvature of the peripheral region, and optimizing the shape. CONSTITUTION:The curvature R2 of the peripheral region 3 is made larger than the curvature R1 of the effective region 1, and the rigidity of a whole shadow mask is increased. The region 1 is a nonspherical face on which the curve center C of the shadow mask is used as an origin, the axis perpendicular to the long axis X-X and the short axis Y-Y is set to the Z-Z axis, and Z is the preset polynomial. The correction quantity DELTAZn is added on a group of points consisting of intersections of a virtual mesh on a curved face with the same curvature as the curvature R1 of the region 1 in the region 3 set at the distance Z from the virtual plane passing through the center C. The region 3 with the curvature R2 larger than the curvature R1 is obtained. If DELTAZ is made larger toward the periphery of the region 3, the curvature outside the effective face is made larger than the curvature inside the effective face, and the rigidity of the whole shadow mask is improved. The rigidity of the flat shadow mask with a large radius of curvature can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask for a color picture tube, and more particularly to a shadow mask for a color picture tube in which rigidity is increased to improve manufacturing accuracy and so-called doming phenomenon caused by temperature rise during operation is reduced. And the manufacturing method thereof.

[0002]

2. Description of the Related Art Shadow masks for color picture tubes (hereinafter referred to as
A shadow mask) is a color selection electrode peculiar to a shadow mask type color picture tube, and has a function of correctly landing electron beams corresponding to, for example, red, green, and blue phosphors.

7A and 7B are views for explaining a conventional shadow mask, FIG. 7A is a front view, FIG. 7B is a side view seen from a short axis direction, and FIG.
FIG. 8 is a side view seen from the long axis direction, and FIG. 8 is an enlarged cross-sectional view taken along line XX of FIG. 7. As shown in the figure, this type of shadow mask is composed of a front wall 11 which is a curved surface having a uniform curvature R _0, and a side wall 2 which is bent at a substantially right angle so as to surround the front wall 11. It has a deep dish shape. The entire curved surface area a of the front wall 11 is connected to the side wall 2 with the uniform curvature R ₀ , and the effective curved surface area a of the front wall 11 has an electron beam passage hole through which an effective electron beam actually passes. There is a region b. The shape of the front wall is usually a rectangular shape having a long axis XX and a short axis YY. When the shadow mask is mounted in the picture tube, it is fixed to a support frame (not shown) and suspended on the face panel wall of the picture tube via the spring means.

In general, the curved surface of the front wall 11 of the shadow mask has its origin at the center C of the curved surface of the shadow mask (center of the front wall), the major axis X--X axis direction position is x, and the minor axis Y is.
If the position in the −Y axis direction is y, and the position in the ZZ axis direction perpendicular to the X axis and the Y axis is z, then a polynomial expression z = f (x, y) is used. In order to solve the doming phenomenon when the curvature of the front wall of the shadow mask is made small (that is, the radius of curvature is made large) to flatten the whole, it is disclosed in, for example, Japanese Patent Laid-Open No. 59-163737. As described above, it is known that the curvature along the major axis is larger in the side portion than in the central portion.

By the way, in this shadow mask, a flat material plate having an effective area b of a curved surface portion is formed into a curved surface by press working. The thickness of the shadow mask material plate is
For example, it is an iron-nickel-based plate material that is as thin as about 0.1 to 0.3 mm. On the other hand, the curvature radius of the shadow mask curved surface portion is as large as about 600 to 1,500 R, and the curved surface portion has a large area. Springback occurs in the shadow mask after press molding.

Therefore, in the press molding of a shadow mask, a press molding die is used in which the springback rate is expected on the curved surface of the shadow mask (Japanese Patent Laid-Open No. 56-173).
No. 9).

[0007]

In response to the recent trend toward larger color image receivers, the flatness of the face panel of the color picture tube has progressed, and accordingly, as described above, the front wall of the shadow mask has been flattened. There is a tendency that the radius of curvature of the curved surface is increased to bring the curved surface closer to a flat surface. However, a shadow mask with a large radius of curvature has a problem in that it cannot obtain sufficient workability in press molding of a curved surface, and the rigidity of the shadow mask structure becomes low due to its curved shape close to a flat surface. is there.

Attempts have been made to reduce the plate thickness as much as possible in order to reduce the cost of the shadow mask material. However, the ultrathin shadow mask in which the plate material is thin has the problem of low rigidity as in the above case. . Further, in a shadow mask having a large radius of curvature and a shadow mask made of a thin plate material, there is a problem that a reproduced image is distorted due to severe doming caused by a temperature rise during operation of the color picture tube.

As described above, in a shadow mask having a large radius of curvature and a thin plate material, the dynamic performance of the color picture tube is often deteriorated and defects are often increased in the manufacturing process. The shadow mask disclosed in JP-A-59-163737, in which the curvature along the major axis is larger in the side portion than in the central portion, has a curved shape of two smooth cylindrical shapes having axes perpendicular to each other. For a face panel that has a curved surface that is formed by the surface and has such two cylindrical surfaces contacting each other at the center of the face panel, the curvature along the major axis is larger in the peripheral portion than in the central portion. However, the basis for setting the curvature is not considered, and the setting of the curved surface of the entire front wall including the minor axis is not mentioned.

The object of the present invention is to optimize the curved surface shape of the entire front wall in both the major axis direction and the minor axis direction of the curved surface so that the rigidity is sufficiently high even in an extremely thin shadow mask and a shadow mask having a large radius of curvature. And a shadow mask having a structure in which the doming phenomenon is less likely to occur, and a method for manufacturing the shadow mask.

[0011]

In order to achieve the above object, the present invention uses a predetermined three-dimensional formula to determine the curvature of the peripheral region in both the major axis and the minor axis of the front wall of the shadow mask. This is achieved by making it larger than the curvature of the effective area. That is, the present invention provides a shadow mask for a color picture tube having a front wall composed of an effective area and a peripheral area surrounding the effective area, in which the effective direction in both the major axis XX and the minor axis YY of the front wall. When the curvature of the region is R ₁ and the curvature of the peripheral region is R ₂ , R ₁ <R ₂ is set, and the curved surface of the front wall is at the boundary between the effective region and the peripheral region. It is characterized by forming a bead that intersects with.

Further, in the shadow mask manufacturing method according to the present invention, the curvature of the point group consisting of the intersection points of the mesh set on the same curved surface as the curvature of the effective area in the peripheral area is larger than that of the curved surface of the effective area. It is characterized in that the peripheral part curvature is made larger than the curvature of the effective region by taking another point group to which such a correction amount is added and forming a curved surface obtained by curve-fitting these point groups.

[0013]

By increasing the curvature of the peripheral area surrounding the effective area with respect to the curvature of the effective surface, sufficient tension can be obtained in forming the curved surface of the shadow mask, so that the entire curved surface is stretched. In addition, the rigidity of the shadow mask structure can be strengthened while keeping the average curvature of the shadow mask curved surface small, the strength can be improved, the occurrence of doming due to the temperature rise during the operation of the color picture tube can be reduced, and the thin plate material is used to reduce the weight. Moreover, a flat shadow mask having high strength can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view (A) illustrating a configuration of an embodiment of a shadow mask according to the present invention, (B) a cross-sectional view in the X-X axis direction, and (C) a cross-sectional view in the Y-Y axis direction. In the figure, 1 is an effective area (a), 2 is a side wall, 3 is a peripheral area (b), 4 is a boundary between the effective area and the peripheral area, R ₁ is a curvature of the effective area, and R ₂ is a peripheral area. Indicates curvature.

As shown in the figure, in this embodiment, the curvature R ₂ of the peripheral area is larger than the curvature R ₁ of the effective area (R ₁
By setting <R ₂ ) the rigidity of the shadow mask as a whole is increased. The curved surface of the effective area 1 may be a spherical surface or a cylindrical surface, but in the present embodiment, the curved surface center C of the shadow mask is normally set as the origin, and the major axis XX, the minor axis YY, and the major axis X. -Z is the axis perpendicular to the X and the minor axis Y-Y.
The Z-axis is an aspherical surface represented by a polynomial Z = f (X, Y).

For example, to give an example of the product to which the shadow mask of the present invention is applied, in the case of a 51 cm (21 type) color picture tube, the shadow mask used for it is the major axis XX and the minor axis in the effective area. The relationship between an arbitrary point (x, y) on Y-Y and the height z between the center point of the front wall is expressed as follows: z = a ₁ x ² + a ₂ x ⁴ + b ₁ y ² + b ₂ y ⁴ + c ₁ x ² y ² + c ₂ x ⁴ y ² + c ₃ x ² y ⁴ + c ₄ x ⁴ y ⁴ ± 0.2 where a ₁ , a ₂ , b ₁ , b ₂ , c ₁ , c ₂ , c ₃ , c ₄ is a constant,
These constants a ₁ , a ₂ , b ₁ , b ₂ , c ₁ , c ₂ , c ₃ , c ₄ are as follows: a ₁ ≈ 0.295 × 10 ³ a ₂ ≈ 0.253 × 10 ⁸ b ₁ ≈ 0 .182 × 10 ³ b ₂ ≈0.613 × 10 ⁸ c ₁ ≈0.259 × 10 ⁷ c ₂ ≈−0.607 × 10 ¹² c ₃ ≈−0.947 × 10 ¹² c ₄ ≈0.230 × 10 ¹⁶ and preferably a ₁ = 0.295064 × 10 ³ a ₂ = 0.252535 × 10 ⁸ b ₁ = 0.181801 × 10 ³ b ₂ = 0.612634 × 10 ⁸ c ₁ = 0.259415. × was _{^{10 7 c 2 = -0.606650 × 10}} 12 c 3 = -0.947074 × 10 12 c 4 = 0.230259 × 10 16. Note that the present embodiment is not limited to this, and shadow masks for color picture tubes of various kinds of sizes, for example, the relational expression between (X, Y) and Z described above is defined up to a sixth-order component, and the shadow mask curved surface is defined. It can also be applied to the one with higher flatness. Further, the curved surface constant can also be changed according to the difference in the electron beam landing function of the color picture tube.

Further, the effective region 1 and the peripheral region 3 may have different curvatures on the major axis XX and the minor axis YY. 2A and 2B are explanatory views of an embodiment of a method for manufacturing a shadow mask for a color picture tube according to the present invention. FIG. 2A is a front view, FIG. 2B is a side view, and FIG. 2C is a part B of FIG. FIG.

In the figure, the center C of the effective area 1
From the virtual plane 6 passing through (x ₀ , y ₀ ) the distance z (x
_n, y _n) is set to the curvature R ₁ and the intersection of the virtual mesh on the same curved surface 1 '7 the effective area 1 in the peripheral region 3 (x
_n, the point group consisting of y _n), taking the effective region 1 of the curved surface other point group obtained by adding the correction amount Delta] z _n as the curvature R ₂ greater than _{5 (x n ', yn'} ), By forming a curved surface 3 ′ obtained by curve-fitting these point groups, the curvature of the peripheral area 3 can be made larger than the curvature of the effective area.

Generally, the magnitude of Δz is increased toward the periphery of the peripheral region 3. Therefore, the height from the center of the shadow mask at each point is z (x _n, y _n ) +
Δz _n . Then, a curved surface that passes through these point groups 7 is defined by, for example, the least squares method, and a shadow mask full curved surface is formed from the two curved surface specifications of the curved surface 3 ′ of the peripheral area and the curved surface 1 of the effective area. As a result, the curvature outside the effective surface can be made larger than the curvature inside the effective surface, the rigidity of the entire shadow mask is increased, and the strength of a flat type shadow mask having an extremely thin and large radius of curvature is increased. You can

FIG. 3 is an explanatory view of another embodiment of the shadow mask for a color picture tube according to the present invention, (A) is a front view, (B) is a side sectional view, and (C) is D of (B). It is an expanded sectional view of a part. In the figure, the same reference numerals as in FIG. 1 correspond to the same portions, and 8 is a bead formed at the boundary between the effective area 1 and the peripheral area 3.

In this embodiment, a groove or bead 8 is formed at the boundary between the effective area 1 and the peripheral area 3 on the front wall of the shadow mask.
Since the above structure is provided, the rigidity can be further increased and the strength can be improved as compared with the shadow mask shown in FIG. In the present embodiment, the case where one beat is provided has been described, but the present invention is not limited to this, and it goes without saying that providing a plurality of beats further improves the strength.

FIG. 4 is an explanatory view showing the strength of the shadow mask according to the present invention in comparison with the strength of the shadow mask according to the prior art. In this strength comparison, as shown in FIGS. 5A and 5B, the shadow mask is welded and fixed to the support frame 20, a required number of suspension springs 30 are provided on the side wall of the support frame, and the suspension spring 30 is attached to the panel 40. The shadow mask assembly 10 is incorporated into the panel 40 by suspending it on a provided stud (not shown), and the corner portion of the flange portion of the shadow mask assembly is pushed in the F direction with a push gauge to be transformed into a shadow mask. The load (kg) of the push gauge at the time of occurrence of is measured. The number of test samples was 5 for the present invention and 3 for the conventional one.

As is clear from the figure, the shadow mask according to the present invention has an average load of deformation of 14.8 kg.
While the conventional shadow mask is 8.67k
The strength of the shadow mask of the present invention was about 70% of that of the conventional shadow mask. FIG. 6 is a schematic diagram of a color cathode ray tube having a shadow mask according to the present invention, in which 10 is a shadow mask assembly and 2 is a shadow mask assembly.
0 is a support frame, 30 is a suspension spring, 40 is a panel, 50 is a funnel, 60 is a neck portion, 70 is a phosphor screen (screen), 80 is a magnetic shield, 90 is a deflection yoke, 100 is a purity adjusting magnet, and 110 is a center. A beam static convergence adjustment magnet, 120 is a side beam static convergence adjustment magnet, 130 is an electron gun, Bc is a center beam, and Bs is a side beam.

A phosphor layer of three colors is formed on the inner surface of the panel 40, and if necessary, a thin film containing SnO ₂ , In ₂ O ₃ or the like for preventing reflection and electrification is formed on the outer surface in a single layer or multiple layers. Has been done. Further, an inner conductive film containing graphite, titanium dioxide, or the like is deposited on required portions of the inner surface of the funnel 50 and the inner surface of the neck portion. The three electron beams from the electron gun 130 are subjected to static convergence adjustment by the purity adjusting magnet 100, the center beam static convergence adjusting magnet 110, and the side beam static convergence adjusting magnet 120, and are applied by the deflection yoke 90 in the horizontal and vertical directions. , And the dynamic convergence magnetic field to scan the phosphor layer on the phosphor screen 70 to form an image. At this time, the landing position of the electron beam to each pixel forming an image is regulated by the shadow mask assembly 10 according to the present invention installed immediately before the phosphor screen 70.

By constructing a color picture tube using the shadow mask according to the present invention, it is possible to reduce the doming of the shadow mask that occurs during operation, and also to reduce the deformation of the shadow mask even if it is made lightweight and highly flat. .

[0026]

As described above, according to the present invention,
By making the curvature outside the effective surface, which is the peripheral portion of the shadow mask, larger than the curvature inside the effective surface, the average curvature of the curved surface of the entire shadow mask is reduced and flattening is facilitated. In addition, the curved surface shape with increased tension makes it possible to increase the mask strength by 70% or more compared with the conventional technique even when the thickness is extremely thin and the radius of curvature is large. A mask can be provided.

[Brief description of drawings]

FIG. 1A is a front view illustrating the configuration of an embodiment of a shadow mask according to the present invention, FIG.
(C) It is a YY axial direction sectional view.

2A and 2B are explanatory views of an embodiment of a method for manufacturing a shadow mask for a color picture tube according to the present invention, in which FIG. 2A is a front view, FIG. 2B is a side view, and FIG. 2C is a portion B of FIG. FIG.

3A and 3B are explanatory views of another embodiment of the shadow mask for a color picture tube according to the present invention, in which FIG. 3A is a front view and FIG.
Is a side sectional view, and (C) is an enlarged sectional view of a portion D of (B).

FIG. 4 is an explanatory diagram showing the strength of a shadow mask according to the present invention in comparison with the strength of a shadow mask according to a conventional technique.

FIG. 5 is a front view of a shadow mask assembly using a shadow mask according to the present invention.

FIG. 6 is a schematic configuration diagram of a color CRT equipped with a shadow mask according to the present invention.

FIG. 7A is a front view illustrating a shadow mask according to a conventional technique, FIG. 7B is a side view seen from a minor axis direction, and FIG.
It is the side view seen from the long axis direction.

8 is an enlarged cross-sectional view of the shadow mask according to the related art shown in FIG. 7, taken along the line XX.

[Explanation of symbols]

1 ... Effective area, 2 ... Side wall, 3 ... Peripheral area, 4 ... Boundary between effective area and peripheral area.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshihiro Takahashi             Hitachi, Ltd. 3300 Hayano, Mobara-shi, Chiba             Mobara Factory

Claims (3)

[Claims] 1. A shadow mask for a color picture tube having a front wall composed of an effective region and a peripheral region surrounding the effective region, wherein the effective region is present in both the major axis XX and the minor axis YY of the front wall. Where R ₁ is R ₁ and the curvature of the peripheral region is R ₂ , R ₁ <R ₂ is set. 2. The shadow mask for a color picture tube according to claim 1, wherein a bead that intersects with a curved surface of the front wall is formed at a boundary between the effective area and the peripheral area. 3. A method of manufacturing a shadow mask for a color picture tube having a front wall in which curvatures of an effective region and a peripheral region surrounding the effective region are different from each other, and a mesh having the same curved surface as the curvature of the effective region in the peripheral region. For the point group consisting of the intersections of, take another point group to which a correction amount that makes the curvature larger than that of the curved surface of the effective area is added, and form a curved surface obtained by curve approximation for these point groups, A method of manufacturing a shadow mask for a color picture tube, characterized in that a partial curvature is made larger than a curvature of an effective area.