JP2002063854A - Shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an impact resistance of a shadow mask used for a flat picture tube by making the area of a hole opened on a front side change, coping with the location where a through-hole is formed. SOLUTION: For the shadow mask 1 having through-holes 2a, 2b formed with back side hole parts 4a, 4b into which electron beam is emitted, and front side hole parts 3a, 3b from which electron beam is traveling outside, forming beam spots into a prescribed shape on a surface to be irradiated, the opening area of front side hole part 3b of the through-hole 2b located at peripheral part of the shadow mask is made smaller than the opening area of front side hole part 3a of the through-hole 2a located at the middle part of the shadow mask. This shadow mask 1 is effective, especially when it is used for flat picture tube.

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 cathode ray tube, and more particularly to a shadow mask excellent in impact strength which is preferably used for a flat type cathode ray tube.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a sectional form of a general shadow mask 51. As shown in FIG. The shadow mask 51 is mounted in a cathode ray tube, and is used for a magnetic shield and for forming a circular beam spot on a fluorescent screen of the cathode ray tube. In such a shadow mask 51, through holes having a predetermined shape are formed in a predetermined pattern. The through holes are formed by etching a thin metal plate.

[0003] The through hole is formed by a back side hole on the side where the electron beam is incident and a front side hole on the side where the electron beam is emitted. The front side hole is formed with a larger area than the back side hole. The area of the front side hole and the area of the back side hole are substantially the same in each part of the shadow mask 51.

More specifically, as shown in FIG. 5, a through-hole 52a provided in the center of the shadow mask 51 and a through-hole 52b provided in the periphery of the shadow mask 51 have a back side hole 54a. , 54b for the front side holes 53a,
The formation position of 53b is different. However, the opening area of each of the front side holes 53a and 53b is substantially the same regardless of the formation position. Also, the opening area of each of the back side holes 54a and 54b is formed to have substantially the same size regardless of the formation position. Further, in the through hole 52b in the peripheral portion, the opening area of the front side hole portion 53b is set to be smaller than the opening area of the surface hole portion 53a in the central portion so that the electron beam is not blocked by the outer peripheral side wall 55b of the front side hole portion 54b. In some cases, it is formed slightly larger.

[0005]

When such a type of shadow mask is used for a general cathode ray tube having a curved display surface, no significant problem occurs even if a drop impact or the like is applied to the cathode ray tube. Was.

However, if the shadow mask is used for a flat cathode-ray tube whose display surface is flat and the radius of the phosphor screen is larger than that of a general cathode-ray tube, the central portion of the shadow mask may be dented due to a drop impact or the like. This was confirmed (see FIG. 6).

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to improve the impact strength of a shadow mask after being used in a flat-type cathode-ray tube. Is changed in accordance with the formation position of the through-hole.

[0008]

According to a first aspect of the present invention, there is provided an array of through holes formed by a back side hole on a side where an electron beam is incident and a front side hole on a side where the electron beam is emitted. In the shadow mask that forms a beam spot of a predetermined shape on the surface to be irradiated, the opening area of the front side hole of the through hole provided in the periphery of the shadow mask is provided in the center of the shadow mask. It is characterized in that it is smaller than the opening area of the front side hole of the through hole.

According to the present invention, the opening area of the front side hole of the through hole provided in the periphery of the shadow mask is larger than the opening area of the front side hole of the through hole provided in the center of the shadow mask. Therefore, the metal portion that is not etched is larger in the peripheral portion of the shadow mask than in the central portion of the shadow mask. Therefore, the central part of the shadow mask is relatively lighter than its peripheral part, and the central part is supported by the relatively heavy, high-strength peripheral part. Even when a stress such as an impact is applied, the shadow mask is not deformed such as a dent.

According to a second aspect of the present invention, in the shadow mask according to the first aspect, the opening area of the front side hole of the through hole is continuously changed at a predetermined rate according to the distance from the center of the shadow mask. Alternatively, it is characterized in that it changes stepwise.

According to the present invention, the opening area of the front side hole portion of the through hole changes continuously or stepwise at a predetermined rate according to the distance from the center of the shadow mask. The shadow mask has a concentric intensity distribution, and the intensity of the shadow mask can be gradually increased from the center toward the periphery. Since such a shadow mask has a regular intensity balance, even if a stress such as a drop impact is applied after the shadow mask is mounted on the cathode ray tube, the shadow mask is not deformed such as a dent.

According to a third aspect of the present invention, in the shadow mask according to the first aspect, a through hole provided in an outer periphery of the shadow mask is formed with the same opening area over the entire periphery. It is characterized in that the opening area of the front side hole of the through hole located between the through hole and the through hole at the center of the shadow mask changes continuously or stepwise at a predetermined change rate.

According to the present invention, since the through-holes formed on the outer periphery of the shadow mask are formed with the same opening area over the entire periphery, the shadow mask having the same strength of the through-hole on the outer periphery can be provided. can do. Further, the through-hole located between the through-hole on the outer periphery and the through-hole at the center of the shadow mask changes such that the opening area of the front side hole portion decreases continuously or stepwise at a predetermined change rate. So
The strength of the shadow mask can be gradually changed from the outer periphery toward the center. Such shadow masks have a very regular intensity balance,
Even if a stress such as a drop impact is applied after being mounted on the cathode ray tube, the shadow mask is not deformed.

The invention according to claim 4 is the invention according to claims 1 to 3.
The shadow mask according to any one of the above, is characterized in that the shadow mask is used for a flat type cathode ray tube.

According to the present invention, when used in a flat cathode-ray tube having a large radius on the fluorescent screen side, the shadow mask is not deformed even when a stress such as a drop impact is applied.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of a shadow mask 1 according to the present invention. FIG. 1A shows a sectional shape of a through hole 2a formed at the center of the shadow mask 1, and FIG. 1 shows a cross-sectional shape when the through hole 2b formed on the outer periphery of the shadow mask 1 is cut by a virtual line extending from the center of the shadow mask 1. FIG. 2 is a schematic front view illustrating the shape and positional relationship of the through holes formed in each part of the shadow mask 1.

In the shadow mask 1 of the present invention, a through hole of a predetermined shape is formed in a predetermined pattern by etching a thin metal plate. The pattern is usually formed by arranging through holes in a substantially close-packed structure or a structure similar thereto. The shadow mask 1 having such a shape is mounted on a cathode ray tube, and is used for a magnetic shield and for forming a beam spot of a predetermined shape on a phosphor screen of the cathode ray tube. The shape of the beam spot may be any of a circular shape or a substantially rectangular slot shape, and the present invention can be applied to any case.
In the following, for convenience, a shadow mask that forms a circular beam spot will be described as an example.

The through holes 2a and 2b are formed as shown in FIG.
Back holes 4a and 4b on the electron beam incident side and front side holes 3a and 3b on the fluorescent screen side of the cathode ray tube and on the side from which the electron beam is emitted are formed. Front side hole 3a,
3b is formed with an area larger than the back side holes 4a and 4b. These through holes 2a and 2b can shield a part of the electron beam from the end portions 9 and the side walls 10 of the back side holes 4a and 4b, and can place a circular beam spot at a predetermined position on the fluorescent screen of the cathode ray tube. Can be formed.

The positional relationship between the front side holes 3a, 3b of the through holes 2a, 2b and the back side holes 4a, 4b differs between the peripheral portion 21 and the central portion 22 of the shadow mask 1, as shown in FIG. I have. Furthermore, the front side hole 3 in the peripheral portion 21
a, 3b and the back side holes 4a, 4b are in the X axis,
It is different in each part of the Y axis and the diagonal axis. Such a difference in the peripheral part 21 prevents the electron beam from being blocked by the outer peripheral side wall 5b of the front side hole part 3b. With such a positional relationship, a circular beam spot can be formed at a predetermined position on the phosphor screen of the CRT with a predetermined size.

More specifically, the central portion 2 of the shadow mask 1
In 2, the electron beam is irradiated almost straight toward the shadow mask 1, so that the center position of the back side hole 4a and the center position of the front side hole 3a may be almost the same. However, in the peripheral portion 21 of the shadow mask 1, since the electron beam is irradiated obliquely toward the shadow mask 1, the center position of the back side hole 4b and the center position of the front side hole 3b are as shown in FIG. The through hole 2b
Needs to be changed depending on the position where is formed. That is, the surface hole 3b is formed so that the position where the through hole 2b is formed is shifted outward as compared with the rear hole 4b as the position toward the peripheral portion 21 is approached.

At this time, the shape of the front side hole portion 3b is gradually flattened from a circular opening shape as going from the central portion 22 to the peripheral portion 21 so as not to shield an electron beam more than necessary, and an elliptical shape or an elliptical shape. It can also be formed so as to transition to an opening shape approximating the shape (see FIG. 7).

Next, the opening area of the front side hole of the through hole will be described.

In the present invention, the opening area T of the front side hole portion 3b of the through hole 2b provided in the peripheral portion 21 of the shadow mask 1 is set to the front side hole portion 3a of the through hole 2a provided in the central portion 22 thereof. The intended purpose is achieved by making the opening area S smaller than the opening area S. Here, the central portion 22 of the shadow mask 1 is a portion including the center of the shadow mask 1 as shown in FIG.
Are portions exemplified by A to H including the outer peripheral portion.

The opening area S of the front side hole 3a in the central part 22 and the opening area T of the front side hole 3b in the peripheral part 21 are shown.
Depends on the size of the cathode ray tube on which the shadow mask 1 is mounted, the size of the radius on the fluorescent screen side of the cathode ray tube, the thickness of the shadow mask 1, the shape of the through hole formed in a circular or slot shape, and the supporting member. It is arbitrarily designed depending on the mounting form of the shadow mask to be supported, processing conditions at the time of press molding, the magnitude of a drop impact, and the like. For example, the opening area S of the front side hole 3a in the central portion 22 is 1
When it is set to 00, the opening area T of the front side hole portion 3b in the peripheral portion 21 is preferably in the range of 80 to 96. At this time, it is more preferably 84 to 92, and still more preferably 86 to 90.

The shadow mask 1 having such a relationship
The peripheral portion 21 has more unetched metal portions than the central portion 22. Therefore, the central portion 22 of the shadow mask 1 is relatively lighter than the peripheral portion 21, and the central portion 22 is supported by the relatively heavy high-strength peripheral portion 21. As a result, even if a stress such as a drop impact is applied after the shadow mask is mounted on the cathode ray tube, the shadow mask 1 is not deformed such as a dent.

The opening area T of the front side hole 3b in the peripheral portion 21 is adjusted by reducing the etching amount of the side wall of the front side hole 3b. Specifically, by changing the etching mask pattern or adjusting the etching conditions,
The side wall 6b on the center side of the shadow mask 1 is
b. By doing so, the opening area T can be further reduced (see FIGS. 1 and 7). Further, by the same means, the side walls 6c and 6d on the side orthogonal to the imaginary line connecting the through hole 2b and the center of the shadow mask 1 are directed toward the center of the surface hole 3b, and the opening area T is further increased. It can also be reduced (see FIG. 7). In the present invention, such adjustments can be employed simultaneously or separately.

When the side wall 6b is directed toward the center of the surface hole 3b, the surface hole 3b
If the length V between the coordinate position of the end 7b and the coordinate position of the ridge 8b of the through-hole 2b is shortened more than necessary, the positional accuracy of the ridge 8b deteriorates. As a result, the hole diameter of the through hole 2b may vary. Therefore, the length V is preferably set in consideration of such points.

On the other hand, even when the side walls 6c and 6d are directed toward the center of the surface hole 3b, the surface hole 3
b, the coordinate positions of the ends 7c and 7d and the ridge 8 of the through hole 2b
If the length W between the coordinate positions c and 8d is shortened more than necessary, the positional accuracy of the ridge portions 8c and 8d deteriorates. As a result, the size of the through hole 2b varies,
The electron beam passing through b may be shielded more than necessary. Therefore, it is preferable to set the length W in consideration of these points.

From the above, the significance of the upper limit of the range of the opening area T when the above-described opening area S is set to 100 is that even if a stress such as a drop impact is applied to the shadow mask after being attached to the cathode ray tube, the shadow mask is not affected. Open area S where deformation does not occur
Is defined. Further, the meaning of the lower limit value defines the limit value of the opening area T at which the center side wall can be shifted in the outer circumferential direction of the shadow mask 1 so as not to hinder the passage of the electron beam.

Further, the front side hole 3a in the central portion 22
With respect to the relationship between the opening area S and the opening area T of the front side hole portion 3b in the peripheral portion 21, the following two modes can be adopted. 3 and 4 are schematic front views illustrating an example in which the opening area of the shadow mask is changed continuously or stepwise.

In the first mode, as shown in FIG. 3, the opening area of the front side hole portion of the through hole is continuously or stepwise at a predetermined change rate according to the distance from the center of the shadow mask 31. It is a changing aspect.

In this embodiment, the through-holes on or near the concentric circle having the same distance from the center of the shadow mask 31 have the same opening area of the front side hole. The rate of change of the opening area that changes according to the distance from the center of the shadow mask 31 may be linear (primary expression) or secondary (secondary expression), and is not particularly limited. The preferable rate of change in the case of a 17-inch shadow mask is the opening area A of the through hole at the center of the shadow mask.
Expressed in relation to (mm ^2), in accordance with the distance R (mm) from the center of the shadow mask, open area (mm ²⁾ is
A-1.06659 × 10 ⁻⁷ × R ² . Where R
Is the distance (mm) from the center. The opening area of the shadow mask other than the 17-inch shadow mask changes in the same tendency.

The shadow mask 31 in such an embodiment has a concentric intensity distribution. Therefore, shadow mask 3
The intensity balance of 1 becomes extremely regular, and the intensity of the shadow mask 31 can be gradually increased from the center toward the outer periphery. The shadow mask 31 is not deformed such as a dent even if stress such as a drop impact is applied after the shadow mask 31 is mounted on the cathode ray tube.

In the second embodiment, as shown in FIG. 4, the through holes provided on the outer periphery of the shadow mask 41 are formed with the same opening area over the entire periphery. Then, the opening area of the front side hole portion of the through hole located between the through hole and the center through hole of the shadow mask 41 changes continuously or stepwise at a predetermined change rate.

In this embodiment, the rate of change from the through-hole in the outer peripheral portion having the same opening area toward the center through-hole can be linear (primary) or secondary (secondary). ) May be used without any particular limitation. When a preferable rate of change in the case of a 17-inch shadow mask is expressed in relation to the opening area A (mm ² ) of the through hole at the center of the shadow mask, a plane for specifying the position from the center of the shadow mask. Hole area (mm ² ) at coordinates (x, y)
Is A-1.96884 × 10 ⁻¹⁰ × x ² −3.660.
68 × 10 ⁻¹⁰ × y ² + 1.62342 × 10 ⁻¹⁴ × (x
× y) It becomes ² . Here, the plane coordinates (x, y) are the coordinate length (mm) from the center. The opening area of the shadow mask other than the 17-inch shadow mask changes in the same tendency.

The intensity balance of the shadow mask 41 in such an embodiment becomes extremely regular, and the intensity of the shadow mask 41 is gradually increased from the center of the shadow mask 41 toward the outer peripheral portion formed with the same intensity. Can be. The shadow mask 41 does not deform, such as a dent, even when stress such as a drop impact is applied after being mounted on the cathode ray tube.

Next, an embodiment in which the shadow mask of the present invention is mounted in a cathode ray tube will be described. FIG. 6 is an explanatory view showing a mode in which the shadow mask is mounted on the flat type cathode ray tube 63. In FIG. 6, a solid line represents the shadow mask 61 of the present invention after a drop impact or the like is applied, and a broken line represents a conventional shadow mask 62 after a drop impact or the like is applied.

The shadow mask 61 of the present invention can be preferably used for a flat-type cathode-ray tube 31 having a flat display surface side and a larger radius on the phosphor screen side than a general cathode-ray tube. Then, even after a drop impact or the like is applied, deformation such as a depression of the central portion of the shadow mask 61 does not occur.

Next, an example of a method for manufacturing the above-described shadow mask will be described. Needless to say, the shadow mask of the present invention is not limited to the following manufacturing method.

The shadow mask 1 can be formed by a conventionally known method. Usually, it is performed in each step of photo etching, and is manufactured by a continuous in-line device. For example, a water-soluble colloid-based photoresist or the like is applied to both surfaces of a thin metal plate and dried. Thereafter, a photomask having the above-described front side hole shape pattern is adhered to the surface thereof, and a photomask having the back side hole shape pattern is closely adhered to the back surface thereof. And develop with water. The positional relationship between the photomask on which the pattern of the front side hole is formed and the photomask on which the pattern of the rear side hole is formed and the shape thereof are determined by the positions of the front side hole and the rear side hole formed on the obtained shadow mask. Designed in consideration of the relationship and their size,
Be placed. The exposed portion of the metal whose periphery is covered by the resist film image is formed in each of the shapes described above based on the difference in the etching progress rate of each portion. In addition,
The etching process is performed by spraying a ferric chloride solution from both sides after heat treatment or the like. Thereafter, a shadow mask is manufactured by continuously performing post-processes such as washing and peeling.

[0042]

The present invention will be described more specifically below with reference to examples and comparative examples.

(Example 1) Fe-N having a thickness of 0.13 mm
A shadow mask 1 for a 17-inch cathode ray tube made of an i-alloy was manufactured by the above-described general shadow mask manufacturing method.

This shadow mask is a shadow mask of a type that forms a circular beam spot on the fluorescent screen of a cathode ray tube.
The density of a and 2b was 2498 / cm ^2, and the opening area of the back side holes 4a and 4b in each part of the shadow mask 1 was about 0.00887 mm ² . Also, the front side hole 3a,
The opening area of 3b is about 0.03398 mm ² at the center of the shadow mask 1, and E,
The outer circumference of each part of F, G and H was about 0.02955 mm ² . Further, the opening area of the front side hole portion of the through hole formed between the center and the outer periphery of the shadow mask was changed so as to be continuously reduced in a linear relationship according to the distance from the center.

The obtained shadow mask has E, F, and F, assuming that the opening area S of the central front side hole 3a is 100.
The opening area T of the front side hole 3b on the outer periphery of each part of G and H is 8
6.97, which is smaller than the central one.
In the through hole 2b provided with such a front side hole 3b,
The side wall 6b constituting the front side hole 3b is formed so as to face the center of the front side hole 3b. The through-hole 2b provided with the front side hole 3b has a metal amount of about 0.1 / per metal compared to the through-hole 2a provided with the central front side hole 3a.
002165 μg more.

The shadow mask was mounted on a flat cathode ray tube, and thereafter, an impact load of 30 G or more was applied to the cathode ray tube. No deformation such as a dent was observed in the shadow mask mounted in the cathode ray tube.

(Example 2) Fe-N having a thickness of 0.13 mm
A shadow mask 1 for a 19-inch cathode ray tube made of i-alloy was manufactured in the same manner as in Example 1.

In this shadow mask, as shown in Table 1, the density of the through holes 2a and 2b formed was 1768 /
cm ^2, and the opening area of the back side holes 4a and 4b in each part of the shadow mask 1 was about 0.01011 mm ² . Also, regarding the opening area of the front side holes 3a and 3b,
The center of the shadow mask 1 is about 0.03398 mm ^2, and the outer circumference of the shadow mask is about 0.3 mm over the entire circumference.
03024 mm ² . Further, the opening area of the front side hole portion of the through hole formed between the center and the outer periphery of the shadow mask was changed so that the distance between the center and the outer periphery was continuously reduced in a linear relationship.

In the shadow mask obtained, when the opening area S of the central front side hole 3a is 100, the opening area T of the front side hole 3b formed on the entire periphery thereof is 88.99, It is smaller than the center one. In the through hole 2b having the front side hole 3b, the side wall 6b constituting the front side hole 3b is formed so as to face the center of the front side hole 3b. The through hole 2b having the front side hole 3b is the same as the through hole 2b having the center front side hole 3a.
compared to a, the amount of metal is about 0.001829 per piece
μg more.

This shadow mask was mounted on a flat cathode ray tube, and thereafter, an impact load of 30 G or more was applied to the cathode ray tube. No deformation such as a dent was observed in the shadow mask mounted in the cathode ray tube.

(Comparative Examples 1 to 3) Shadow masks for cathode ray tubes of 17 inches to 21 inches were formed as shown in Table 1. At this time, for Comparative Examples 1 and 2,
The opening area of the front side hole is increased from the center of the shadow mask toward the outer periphery. Further, in Comparative Example 3, the opening area of the front side hole is the same over the entire shadow mask.

These shadow masks were mounted on a flat cathode-ray tube, and thereafter, an impact load of 30 G or more was applied to the cathode-ray tube. The shadow mask mounted in the cathode ray tube had a dent at the center as shown in FIG.

[0053]

[Table 1]

[0054]

As described above, according to the shadow mask of the present invention, the unetched metal portion is more in the peripheral portion than in the central portion. In addition, since the central portion is supported by the relatively heavy peripheral portion having high strength, no dent occurs in the central portion even when stress is applied due to a drop impact or the like.

Further, the intensity balance of the shadow mask is made extremely regular by changing the opening area of the surface hole of the through hole continuously or intermittently between the center and the outer periphery of the shadow mask. Can be. As a result, the strength of the shadow mask can be gradually increased from the center toward the outer periphery, and the shadow mask is not deformed even when a stress such as a drop impact is applied after the shadow mask is mounted on the cathode ray tube.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a shadow mask according to the present invention, in which (a) is a cross-sectional shape of a through hole formed at the center of the shadow mask, and (b) is formed on the outer periphery of the shadow mask. This is a cross-sectional shape when the through hole is cut by a virtual line extending from the center of the shadow mask.

FIG. 2 is a schematic front view illustrating a shape and a positional relationship of a through hole formed in each part of the shadow mask.

FIG. 3 is a schematic front view illustrating an example in which the opening area of a shadow mask is changed continuously or intermittently.

FIG. 4 is a schematic front view illustrating another example in which the opening area of the shadow mask is changed continuously or intermittently.

FIG. 5 is a sectional view showing an example of a sectional form of a general shadow mask.

FIG. 6 is an explanatory view showing a mode in which a shadow mask is mounted on a flat type cathode ray tube.

FIG. 7 is a front view showing an example of a shape of a through hole formed in each part when viewed from the front.

[Explanation of symbols]

1, 31, 41, 51, 61, 62 Shadow masks 2a, 2b, 52a, 52b Through holes 3a, 3b, 53a, 53b Front side holes 4a, 4b, 54a, 54b Back side holes 5b, 55b Outer side wall 6b, 6c, 6d Side wall 7b Edge of surface hole 8b, 8c, 8d Edge 9 Edge of back side hole 10 Side wall of back side hole 21 Peripheral part 22 Central part 63 Flat type cathode ray tube T, S Opening of front side hole Hole area V, W Length between coordinate position of edge and coordinate position of ridge

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Makita 1-1-1, Ichigaya-Kagacho, Shinjuku-ku, Tokyo Dai-Nippon Printing Co., Ltd. F-term (reference) 5C031 EE02 EF02 EF06 EG01 EH06

Claims (4)

[Claims] A back hole on a side where an electron beam is incident;
A through-hole formed from a front side hole on the side from which the electron beam is emitted is arranged, and a shadow mask for forming a beam spot of a predetermined shape on an irradiated surface is provided at a peripheral portion of the shadow mask. A shadow mask, wherein the opening area of the front side hole of the through hole is smaller than the opening area of the front side hole of the through hole provided at the center of the shadow mask. 2. The method according to claim 1, wherein the opening area of the front side hole of the through hole changes continuously or stepwise at a predetermined change rate according to the distance from the center of the shadow mask. The described shadow mask. 3. A through hole provided on the outer periphery of the shadow mask is formed with the same opening area over the entire periphery thereof, and between the through hole and the through hole at the center of the shadow mask. The shadow mask according to claim 1, wherein the opening area of the front side hole of the located through hole changes continuously or stepwise at a predetermined change rate. 4. The shadow mask according to claim 1, wherein the shadow mask is used for a flat type cathode ray tube.