JP2002093340A - Shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shadow mask of which, the opening width of front side hole parts are made to change corresponding to the position where the through hole is formed, for improving the shock resistant strength of the shadow mask after used for a flat-shaped cathode ray tube. SOLUTION: The shadow mask is formed by arranging through holes 2a, 2b having back side hole parts 4a, 4b formed at the side that electron beam comes in, and front side hole parts 3a, 3b formed at the side that electron beam goes out, and forms beam spots with prescribed shape on an irradiated surface. For the front side hole part 3b formed at the peripheral part of the shadow mask in elliptic shape, the opening width T in the direction P perpendicular to an imaginary line extending from the center of the shadow mask is formed smaller than the opening width S of the front side hole part 3a formed at the center of the shadow mask, and the opening width T of the front side opening 3b is made less than 1.46 times the wall thickness of the shadow mask.

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. 8 shows an example of a cross section of a general shadow mask 51. As shown in FIG. The shadow mask 51 is mounted in a cathode ray tube and is used to form 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. 8, 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 size and the opening area of each of the front side holes 53a and 53b are substantially the same size regardless of the formation position. Also, the opening dimensions and the opening areas of the back side holes 54a and 54b are formed to have substantially the same size regardless of the formation position. Furthermore, the peripheral through-hole 52b
In order to prevent the electron beam from being shielded from the side wall 55b of the shadow mask 51 on the side wall of the front side hole portion 54b, the opening size and the opening area of the front side hole portion 53b are set at the central portion. There is an actual example in which the opening size and the opening area of the front side hole portion 53a are formed slightly larger than the opening size and the opening area.

[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 the broken line in FIG. 7).

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 a shadow mask that forms a beam spot of a predetermined shape on the irradiated surface, the front side hole formed in the periphery of the shadow mask has an opening width in a direction orthogonal to a virtual line extending from the center of the shadow mask. Has a substantially elliptical shape formed smaller than the opening width of the front side hole formed in the center of the shadow mask.

According to the present invention, the front side hole formed in the peripheral portion of the shadow mask has an opening width in a direction orthogonal to an imaginary line extending from the center of the shadow mask, the front side formed at the center of the shadow mask. It has a substantially elliptical shape formed smaller than the opening width of the hole. In the peripheral portion of the shadow mask thus formed, the metal portion that has not been etched is larger than in the central portion. 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 of the first aspect, the opening width of the front side hole formed in the peripheral portion is 1.46 times or less the plate thickness of the shadow mask. It has a special feature.

According to the present invention, the opening width of the front side hole formed in the peripheral portion is set to 1.46 times or less the thickness of the shadow mask. A shadow mask having an opening width in this range does not undergo deformation such as dents even when stress such as a drop impact is applied after being mounted on a cathode ray tube.

According to a third aspect of the present invention, in the shadow mask according to the first or second aspect, the opening width of the front side hole portion of the entire shadow mask including the front side hole portion formed in the peripheral portion is set to the width. It is characterized in that it changes continuously or stepwise at a predetermined change rate according to the distance from the center of the shadow mask.

According to the present invention, the opening width of the front side hole portion over the entire shadow mask including the front side hole portion formed in the peripheral portion is continuously changed at a predetermined rate according to the distance from the center of the shadow mask. Alternatively, since the shadow mask changes so as to be gradually reduced, the shadow mask has a concentric intensity distribution, and the intensity of the shadow mask can be gradually increased from the center toward the peripheral portion. 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 fourth aspect of the present invention, in the shadow mask according to the first or second aspect, the opening width of the front side hole portion of the entire shadow mask including the front side hole portion formed in the peripheral portion is as described above. The opening width of the front-side hole located between the front-side hole and the center front-side hole of the shadow mask is the same at the outermost front-side hole of the shadow mask. Alternatively, it is characterized in that it changes stepwise.

According to the present invention, since the opening width of the front side hole portion at the outermost periphery of the shadow mask is the same, the shadow mask can be formed so that the outermost periphery has the same strength. Further, the opening width of the front side hole located between the outermost outer side hole and the center front side hole of the shadow mask changes continuously or stepwise at a predetermined change rate. Can be gradually changed from the outermost periphery toward the center. Such a shadow mask has an extremely regular strength balance, so that 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.

[0016]

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

FIG. 1 is a front view showing an example of a through hole 2 formed in a shadow mask 1 of the present invention. FIG. 1A shows a through hole formed in the center of the shadow mask 1.
(B) is a through hole formed on the outer periphery of the shadow mask 1. FIG. 2 is a cross-sectional view showing an example of the through holes 2a and 2b of each section shown in FIG. 1, and FIG. 3 is a cross-sectional view showing another example of the through holes 2a and 2c of each section shown in FIG. FIG. 4 is a schematic front view illustrating the 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 a circular shape or a substantially rectangular slot shape, and the technical idea of 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.

First, the shape of the through hole will be described.

As shown in FIGS. 1 and 2, the through holes 2a and 2b are formed on the back side holes 4a and 4b on the side where the electron beam is incident.
And the front side holes 3a and 3b located on the fluorescent screen side of the cathode ray tube and emitting the electron beam. The front side holes 3a and 3b are formed with a larger area 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.

Front side hole 3 forming through holes 2a, 2b
As shown in FIGS. 1 and 2, the positional relationship between the a and 3b and the back side holes 4a and 4b is different between the peripheral portion 21 and the central portion 22 of the shadow mask 1 shown in FIG. Further, even in the same peripheral portion 21, the positional relationship between the front side holes 3a, 3b and the back side holes 4a, 4b is different between the X axis, the Y axis, and the diagonal axis. Such a difference is that the electron beam is prevented from being shielded from light on the side wall 5b on the outer peripheral side of the shadow mask on the side wall of the front side hole 3b.
With such a positional relationship, a circular beam spot can be formed at a predetermined position on the phosphor screen of the cathode ray tube with a predetermined size. 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. Further, the peripheral portion 21 of the shadow mask 1 is a portion exemplified by A to H including the outer peripheral portion, and here, 10 m from the outermost through hole.
It indicates a range including a part which is inside by about m.

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. On the other hand, in the peripheral portion 21 of the shadow mask 1,
Since the electron beam is obliquely irradiated 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 determined by the positions A to H (see FIG. 4) where the through holes 2b are formed. )). That is,
Depending on the direction in which the through hole 2b is formed from the center of the shadow mask, the front side hole portion 3b of the through hole 2b
It is formed so as to shift toward the outer peripheral side of the shadow mask with respect to the back side hole 4b. Further, as the position where the through hole 2b is formed goes from the central part 22 to the peripheral part 21 side,
The front side hole 3b of the through hole 2b is formed so as to be gradually shifted toward the outer periphery of the shadow mask as compared with the back side hole 4b. At this time, the shape of the front side hole portion 3b is flattened so as to gradually transition from a circular shape to an elliptical shape or an opening shape approximating to an elliptical shape as going from the central portion 22 to the peripheral portion 21. Shape "is preferred.
By doing so, the front side hole portion 3b of the through hole 2b is
It is possible to prevent the electron beam from being shielded more than necessary.

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

In the present invention, the front side hole 3b formed in the peripheral portion 21 of the shadow mask 1 is formed with an opening width T in a direction P orthogonal to an imaginary line extending from the center of the shadow mask 1.
The desired object is achieved by forming a substantially elliptical shape in which is formed smaller than the opening width S of the front side hole portion 3a formed at the center of the shadow mask 1.

The relationship between the opening width T of the front side hole 3b in the peripheral portion 21 and the opening width S of the front side hole 3a formed at the center depends on the size of the CRT on which the shadow mask 1 is mounted, the CRT. Size of the fluorescent screen side, the thickness of the shadow mask 1, the shape of the through hole having a circular or slot shape, the mounting form of the shadow mask supported by the support member, the processing conditions during press molding, the drop impact It is arbitrarily designed depending on the size, etc.

In particular, in the present invention, the opening width T of the front side hole portion 3b in the peripheral portion 21 is preferably not more than 1.46 times the plate thickness of the shadow mask. At this time, it is more preferably 1.40 times or less, and still more preferably 1.3 times.
6 times or less.

The through-hole of the peripheral portion 21 having the opening width T in such a range reduces the spatial volume of the front side hole 3b. Such a decrease in the space volume of the front side hole 3b is as follows.
Since the space volume in the entire through hole of the peripheral portion 21 is reduced, the metal portion of the through hole of the peripheral portion 21 that is not etched is relatively larger than that of the through hole 2a of 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 size of the opening width T can be adjusted to the above-mentioned preferable range by changing the etching mask pattern and the etching conditions.

At this time, for example, the opening width T of the front side hole portion 3b in the peripheral portion 21 is set to be 1.4 times the plate thickness of the shadow mask.
In the case where the size is 6 times or less, the end 7 of the front side hole 3b is used.
If the length W between the coordinate positions of c and 7d and the coordinate positions of the ridge portions 8c and 8d of the through hole 2b 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 may vary, or the electron beam passing through the through hole 2b may be shielded more than necessary. The length W and the opening width T including the length W are preferably set in consideration of such points. In addition,
The “ridge line portion 8e” is a portion formed by the side wall 10e of the back side hole 4b and the side wall 5b of the front side hole 3b.

The opening width T is set to 1.4 of the thickness of the shadow mask.
The reason why the size is set to 6 times or less is to prevent the shadow mask from being deformed even when a stress such as a drop impact is applied after the shadow mask is mounted on the cathode ray tube. On the other hand, the lower limit of the opening width T is to prevent the size of the through-hole 2b from being varied and the electron beam passing through the through-hole 2b from being unnecessarily blocked. If the opening width T is specifically defined in comparison with the plate thickness of the shadow mask, it is 1.20 times or more, preferably 1.2 times, the plate thickness.
It is 4 times or more, more preferably 1.26 times or more. Strictly speaking, this value is slightly affected by the shadow mask standard, for example, the size of the shadow mask, the size and shape of the through-hole, and the like. It is preferable to set T in the above range.

Further, in the shadow mask of the present invention, in addition to the method of reducing the opening width T, as shown in FIG. 3, the center side wall 6b of the shadow mask 1 is positioned at the center of the front side hole 3b. By facing, the metal portion of the front side hole 3b can be relatively increased, which is convenient for increasing the strength of the peripheral portion 21 (FIGS. 2 and 3).
See and compare. ). When the above-mentioned side wall 6b is directed toward the center of the front side hole 3b, the end 7b of the front side hole 3b is set.
If the length V between the coordinate position of the ridge line portion 8b and the coordinate position of the ridge line portion 8b of the through hole 2b is shortened more than necessary, the positional accuracy of the ridge line portion 8b will be deteriorated, and the hole diameter of the through hole 2b may vary. Therefore, the length V is set in consideration of these points, but in actual production, the length V at which the appearance quality is maintained.
Is about 10 μm.

The length U between the coordinate position of the end 7e of the front side hole 3b and the coordinate position of the ridge 8e of the through hole 2b.
Are the angle at which the electron beam is incident based on the coordinate position where the through hole 2b is formed, the sectional height (the height from the end 9 of the back side hole 4b to the ridge 8e), the plate thickness t, and the like. It is a design item that is automatically determined by

Next, an embodiment in which the opening width is changed continuously or stepwise will be described.

The front side hole formed in the shadow mask is
It is preferable that the opening width is formed so as to change continuously or stepwise at each part on the shadow mask, and the following two modes can be adopted.

FIGS. 5 and 6 are schematic front views illustrating an example in which the opening width of the front side hole is changed continuously or stepwise.

In the first mode, as shown in FIG. 5, the opening width T of the front side hole 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 an aspect which changes to.

In this embodiment, the through-holes on or near the concentric circles having the same distance from the center of the shadow mask 31 have the same opening width T of the front side hole. The rate of change of the aperture width T that changes according to the distance from the center of the shadow mask 31 may be linear (primary equation) or secondary (secondary equation), and is not particularly limited. For example, in the case of a 17-inch shadow mask, when the preferable change rate is expressed in relation to the thickness t (mm) of the shadow mask, the opening width T (mm) is (α-0.
000183 × R) × 0.130 ÷ t. Here, α is the opening width (mm) of the front side hole formed at the center of the shadow mask, and R is the distance (mm) from the center.
It is. At this time, it is preferable to adjust the opening width T of the front side hole portion in the peripheral portion 21 defined as a region that enters 10 mm inside from the outermost periphery so as to be 1.46 times or less the plate thickness. The above relationship is the same for shadow masks other than those for 17 inches, and it is preferable to change and set the opening width with the same tendency.

The shadow mask 31 of 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 mode, as shown in FIG. 6, the opening width T of the front side hole portion of the through hole is formed to be the same in the outermost outer side surface hole portion. Then, the opening width T of the front side hole formed between the front side hole and the front side hole at the center of the shadow mask 41 changes continuously or stepwise at a predetermined change rate.

In this embodiment, the opening width T of the front side hole is
Changes from the outermost through hole having the same opening width toward the center through hole, and the rate of change is linear (primary expression) or secondary (secondary expression). There is no particular limitation. For example, when a preferable change rate of a 17-inch shadow mask is expressed in relation to the thickness t (mm) of the shadow mask, the plane coordinates (x, y) for specifying the position from the center of the shadow mask Is the opening width T (mm) of (α-1.570 × 10 ⁻⁶ × x ² −
2.727 × 10 ^-6 × y ² + 1.361 × 10 ^-10 ×
(X × y) ² ｝ × 0.130 ÷ t. Here, α is the opening width (mm) of the front side hole formed at the center of the shadow mask, and the plane coordinates (x, y) are the coordinate length (mm) from the center. At this time, it is preferable to adjust the opening width T of the front side hole portion in the peripheral portion 21 defined as a region that enters 10 mm inside from the outermost periphery so as to be 1.46 times or less the plate thickness. The above relationship is the same for shadow masks other than those for 17 inches, and it is preferable that the aperture width be changed and set in a similar tendency. Nari, shadow mask 4
1 can be gradually increased from the center of the shadow mask 41 toward the outer peripheral portion formed with the same intensity. 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. This second aspect can be more preferably applied to the shadow mask of the present invention than the first aspect described above.

Next, an embodiment in which the shadow mask of the present invention is mounted in a cathode ray tube will be described. FIG. 7 is an explanatory diagram showing a mode in which a shadow mask is mounted on a flat-type cathode ray tube 63. In FIG. 7, 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 in which a dent occurs after the 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.

[0045]

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

(Example 1) Fe-
The shadow mask 1 for a 17-inch cathode ray tube made of a Ni alloy was manufactured by the above-described shadow mask manufacturing method.

This shadow mask is of a type in which a circular beam spot is formed on the fluorescent screen of the cathode ray tube.
The density of a, 2b is 2498 / cm ² , the opening area of the back side holes 4a, 4b in each part of the shadow mask 1 is about 0.00887 mm ^2, and the opening area of the front side holes 3a, 3b is: At the center of the shadow mask 1, about 0.
03398 mm ^2, and about 0.02955 mm ² at the outermost periphery of the shadow mask over the entire week.

The front side holes 3a, 3b of this shadow mask
Is about 0.175 mm at the outermost periphery of the shadow mask 1 and 1.35 times the plate thickness t. Then, the opening width T of the front side hole portion of the through hole formed between the center of the shadow mask and the outermost periphery changes so as to continuously decrease in a quadratic relation according to the distance from the center. I let it. Specifically, it was changed by a relational expression of -0.0000001019 × R ² . At this time, 1
The opening width T of the area (each part of A to H) into which 0 mm has entered
The thickness was set within a range of 1.35 times to 1.40 times the thickness t.

At this time, the through hole 2b provided with the front side hole 3b has a metal amount about 3 μg larger per unit than the through hole 2a provided with the central front side hole 3a.

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.

(Example 2) Fe-Fe of thickness t0.13 mm
A shadow mask 1 for a 19-inch cathode ray tube made of a Ni 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 / hole.
cm ^2, and the opening area of the back side holes 4 a and 4 b in each part of the shadow mask 1 is about 0.00887 mm ² ,
The opening area of the front side holes 3a and 3b is about 0.03398 mm ² at the center of the shadow mask 1 and about 0.0302 over the entire outer circumference of the shadow mask.
4 mm ² .

The front side holes 3a, 3b of this shadow mask
Is about 0.175 mm at the outermost periphery of the shadow mask 1 and 1.35 times the plate thickness t. Then, the opening width T of the front side hole portion of the through hole formed between the center of the shadow mask and the outermost periphery changes so as to continuously decrease in a quadratic relation according to the distance from the center. I let it. Specifically, it was changed by the relational expression of -0.000000748 × R ² . At this time, 1
The opening width T of the area (each part of A to H) into which 0 mm has entered
The thickness was set within a range of 1.35 times to 1.40 times the thickness t.

At this time, the through-hole 2b provided with the front side hole 3b has a larger amount of metal by about 2.5 μg per piece than the through-hole 2a provided with the central front side hole 3a.

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.

(Comparative Examples 1 to 3) Shadow masks for cathode ray tubes of 17 inches to 21 inches were formed as shown in Table 1 according to Example 1.

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.

[0058]

[Table 1]

[0059]

As described above, according to the shadow mask of the present invention, the metal portion which is not etched in the peripheral portion is larger than that in the central portion, so that the central portion of the shadow mask is higher than the peripheral portion. Is relatively light, and its central part is supported by the relatively heavy, high-strength peripheral part, so even if stress such as a drop impact is applied after the shadow mask is mounted on the CRT, it will dent into the shadow mask. No deformation such as occurs.

Further, the opening width of the front side hole formed in the peripheral portion is defined within a predetermined range with respect to the thickness of the shadow mask, and the opening width T of the front side hole is set at the center of the shadow mask. The intensity balance of the shadow mask can be made extremely regular by changing continuously or stepwise between the outer periphery and the outer periphery. 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 is not deformed.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a through-hole formed in a shadow mask of the present invention. FIG. 1 (a) is a through-hole formed at the center of the shadow mask, and FIG. It is a formed through hole.

FIGS. 2A and 2B are cross-sectional views illustrating an example of a through hole formed in a shadow mask of the present invention. FIG. 2A is a through hole formed in the center of the shadow mask, and FIG. The formed through hole is cut by a virtual line extending from the center of the shadow mask.

3A and 3B are cross-sectional views illustrating another example of a through hole formed in the shadow mask of the present invention, wherein FIG. 3A is a through hole formed at the center of the shadow mask, and FIG. The through hole formed in the outer periphery is cut by a virtual line extending from the center of the shadow mask.

FIG. 4 is a schematic front view illustrating the positional relationship of through holes formed in each part of the shadow mask.

FIG. 5 is a schematic front view illustrating an example in which the opening width of the shadow mask is changed continuously or stepwise.

FIG. 6 is a schematic front view illustrating another example in which the aperture width of the shadow mask is changed continuously or stepwise.

FIG. 7 is an explanatory view showing a mode in which a shadow mask is mounted on a flat type cathode ray tube.

FIG. 8 is an explanatory diagram showing an example of a cross-sectional form of a general shadow mask.

[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, 7e Edge of front side hole 8b, 8c, 8d, 8e Ridge line 9 End of back side hole 10 Side wall of back side hole 21 Peripheral part 22 Central part 63 Flat type cathode ray tube P shadow mask Direction perpendicular to the virtual line extending from the center TP Opening width in the P direction S Opening width of the front side hole formed at the center of the shadow mask V, W Between the coordinate position of the edge and the coordinate position of the ridgeline length

Continuation of 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 EF03 EG02 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 that forms a beam spot of a predetermined shape on an irradiated surface is formed around the shadow mask. The front side hole has a substantially elliptical shape in which an opening width in a direction orthogonal to a virtual line extending from the center of the shadow mask is formed smaller than the opening width of the front side hole formed in the center of the shadow mask. A shadow mask, characterized in that: 2. The shadow mask according to claim 1, wherein an opening width of the front side hole formed in the peripheral portion is 1.46 times or less a plate thickness of the shadow mask. 3. An opening width of a front side hole portion of the entire shadow mask including a front side hole portion formed in the peripheral portion is continuously or stepwise at a predetermined change rate according to a distance from a center of the shadow mask. The shadow mask according to claim 1, wherein the shadow mask changes. 4. An opening width of a front side hole portion of the entire shadow mask including a front side hole portion formed in the peripheral portion is the same at an outermost periphery of the shadow mask. 3. The shadow mask according to claim 1, wherein an opening width of the front side hole located between the center of the shadow mask and the front side hole changes continuously or stepwise at a predetermined change rate. The described shadow mask.