JPH07192644A - Shadow mask for color cathode-ray tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a shadow mask having sufficient mechanical strength with no collision of an electron beam against a side wall by forming a large hole in one face side into a peanut shape with an electron beam deflecting direction serving as the major diameter, and forming a small hole in the other face side into a circular shape. CONSTITUTION:In a shadow mask for a color cathode-ray tube wherein many electron beam passing holes are provided with a prescribed arranging pitch in a plate-shaped member, the electron beam passing hole is constituted of a large hole 25 formed in one face side of the plate-shaped member and a small hole 24 formed in the other face side. Further in the large hole 25, in accordance with approaching the periphery from the center of the shadow mask, a deflecting direction of an electron beam is formed into a major diameter, and further this major diameter is increased larger, in accordance with a deflecting angle of the electron beam, into peanut shape, oval shape, potbelly shape, etc. On the other hand, the small hole 24 is formed in a circular shape of positioning its center on a major axis of the large hole 25. This large hole 25 is formed by double-punch etching by using a resist film to displace the center position of a circular dot from the one face side of the plate-shaped member.

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 cathode ray tube, and more particularly to a shadow mask for a color cathode ray tube which is effective for a color cathode ray tube for a display and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 10, a color cathode ray tube has an envelope made up of a panel 1 and a funnel 2 integrally joined to the panel 1, and the inside of the panel 1 has a blue, A phosphor screen 3 including a three-color phosphor layer that emits green and red is formed, and a shadow mask 4 is arranged inside the phosphor screen 3 at a predetermined distance. On the other hand, inside the neck 5 of the funnel 2,
An electron gun 7 that emits three electron beams 6 is arranged.
Then, the three electron beams 6 emitted from the electron gun 7 are deflected by the magnetic field generated by the deflecting device 8 mounted outside the funnel 2, and the phosphor screen 3 is horizontally and vertically scanned through the shadow mask 4. As a result, a structure for displaying a color image is formed.

The shadow mask 4 has three electron beams 6
Is for selecting so as to properly land on the three-color phosphor layer, and comprises a mask body 10 and a mask frame 11 attached to the peripheral portion of the mask body 10 as shown in FIG. The mask body 10 has an effective surface in which a large number of electron beam passage holes are formed in a predetermined arrangement pitch, and the shadow mask 4 has a panel 1 so that the effective surface faces the phosphor screen at a predetermined distance.
Is located inside.

Among such color cathode ray tubes, particularly in the color cathode ray tube for display, the electron beam passage hole of the shadow mask 4 is formed in a circular shape, and correspondingly, the three-color phosphor layer of the phosphor screen 3 is formed. Are formed in a circular dot shape. FIG. 12 shows the sectional shape of the electron beam passage hole of the shadow mask. In general, the electron beam passage hole 13 of the shadow mask is an inclined side wall in which a large hole 14 formed on one surface side facing the phosphor screen and a small hole 15 formed on the other surface side (electron gun side) communicate with each other. A large hole 14 and a small hole 15
The communicating portion with and substantially determines the hole diameter and shape of the electron beam passage hole 13.

In a color cathode ray tube having such a shadow mask, the electron beam 6 incident on the center of the screen is
Crosses the electron beam passage hole 13 in the center of the shadow mask 4 vertically, but the electron beam 6 obliquely crosses the electron beam passage hole 13 in the periphery of the shadow mask 4 as it goes to the peripheral portion of the screen. become.

In order to prevent the electron beam 6 traversing the electron beam passage hole 13 from colliding with the side wall of the electron beam passage hole 13 and being reflected toward the phosphor screen, the electron beam passage hole 13 is provided with a shadow indicated by a point A0 in FIG. At the center of the mask 4, as shown in FIGS. 13 (a) and 13 (b), the large hole 14 and the small hole 15 are coaxial, but on the horizontal axis (H axis) shown by the point AH in FIG. In the peripheral portion, as shown in FIGS. 13C and 13D, the large hole 14 is eccentric to the small hole 15 outward in the horizontal direction. Further, in the peripheral portion on the vertical axis (V axis) indicated by the point AV in FIG. 11, as shown in FIG.
With respect to the small hole 15, the large hole 14 is located outside in the vertical direction, and in the peripheral portion on the diagonal axis (D axis) indicated by the point AD in FIG.
As shown in FIG. 13 (f), the large hole 14
Is eccentric to the outside in the diagonal direction. That is, in the electron beam passage hole of the shadow mask, the large hole 14 is made smaller than the small hole 15 so that the electron beam does not collide with the side wall of the electron beam passage hole and is reflected in the phosphor screen direction. It is eccentric in the deflection direction.

With respect to color cathode ray tubes for displays, the angle of the electron beam crossing the electron beam passage hole of the shadow mask has become much larger in recent years due to higher definition, higher brightness and flatness. Larger eccentricity of the large hole with respect to or the larger hole needs to be made larger.

However, since the electron beam passage hole of the shadow mask is formed by the photo-etching method and the etching greatly progresses in the plate thickness direction of the plate member, if the eccentric amount of the large hole with respect to the small hole becomes large, As shown in 14, the communication portion 16 of the large hole 14 and the small hole 15 that substantially determines the hole diameter and shape of the electron beam passage hole is not circular,
In addition, the shape of the communicating portion is not stable, and defective hole shapes frequently occur. Further, as shown in FIG. 15, when the large holes 14 are made large, the distance b between the large holes 14 of the adjacent electron beam passage holes becomes narrow, and the mechanical strength of the shadow mask is lowered. As a result, deformation, impact resistance, and vibration resistance are deteriorated, making it unusable for practical use.

[0009]

As described above, in the color cathode ray tube, the electron beam incident on the center of the screen vertically crosses the electron beam passage hole in the center of the shadow mask, but approaches the peripheral portion of the screen. The electron beam obliquely crosses the electron beam passage hole in the peripheral portion. Therefore, the electron beam passage hole of the shadow mask is
In the center of the shadow mask, a large hole on one surface side and a small hole on the other surface side are formed coaxially so that the electron beam does not collide with the side wall and reflect in the phosphor screen direction. However, the large holes are largely eccentric with respect to the small holes outward in the deflection direction. The eccentricity of the large hole with respect to the small hole is particularly large in recent years in a color cathode-ray tube for display with high definition, high brightness, and flatness, because the angle of the electron beam that crosses the electron beam passage hole of the shadow mask is further increased. Along with this, it is necessary to make the large holes more eccentric with respect to the smaller holes or to make the large holes larger.

However, when the amount of eccentricity of the large hole with respect to the small hole becomes large, the etching for forming the electron beam passage hole of the shadow mask greatly advances in the plate thickness direction of the plate member, so that the electron beam passage hole is substantially formed. The communication part between the large hole and the small hole, which determines the hole diameter and shape, is not circular, and the shape of the communication part is not stable, resulting in frequent hole shape defects. Further, if the large holes are made large, the distance between the large holes of the adjacent electron beam passage holes becomes narrower, and the mechanical strength of the shadow mask is lowered, so that there is a problem that it cannot be practically used.

The present invention has been made to solve the above-mentioned problems, and the communication portion between the large hole and the small hole that substantially determines the shape of the electron beam passage hole is circular, and the electron beam is also formed. An object of the present invention is to obtain a shadow mask in which an electron beam that obliquely crosses a passage hole does not collide with a side wall of the electron beam passage hole, and yet the mechanical strength is sufficiently maintained.

[0012]

A large number of electron beam passage holes formed in a plate member at a predetermined arrangement pitch are formed in a large hole formed on one surface side of the plate member and on the other surface side. In the shadow mask for a color cathode-ray tube consisting of a small hole and an electron beam passing hole, the deflection direction of the electron beam is made longer as the large hole approaches the periphery from the center of the shadow mask, and this longer diameter becomes the deflection angle of the electron beam. Therefore, a peanut shape, an oval shape, or a daruma shape, which is large, is formed, a small hole has a circular shape, and the center of this small hole is located on the major axis of the large hole.

Further, the peanut-shaped, oval-shaped or daruma-shaped electron beam passage hole is composed of at least two circular holes which are overlapped, and the small hole of the electron beam passage hole is one of the two circular holes of the shadow mask. It was formed coaxially with the large circular hole located on the center side.

Photosensitive films are formed on both surfaces of the plate-like member by coating, and the photosensitive films on both surfaces are respectively formed with a first photomask having a pattern for large holes and a second photomask having a pattern for small holes. Through exposure and development to form a resist film having a pattern corresponding to the pattern of each photomask on both sides of the photosensitive film, and etching the plate-shaped member on which this resist film is formed from both sides In a method of manufacturing a shadow mask for a color cathode-ray tube in which a large hole is formed on one surface side of a member and a small hole is formed on the other surface side to form an electron beam passage hole, the large hole pattern of the first photomask is formed by The center positions of the circular dots are shifted by an interval corresponding to the deflection angle of the electron beam in the beam deflection direction, and the circular dots are hit twice, so that the circular dots partially overlap or are separated from each other. And turn the small hole patterns of the second photomask is circular, these first and to form the electron beam apertures in the plate-like member by using a second photomask.

Further, in the method for manufacturing a shadow mask for a color cathode ray tube, in the large hole pattern of the first photomask, the center positions of the circular dots are set to 2 at intervals corresponding to the deflection angle of the electron beam in the deflection direction of the electron beam. It was beaten to form a peanut shape.

Further, the large hole pattern of the first photomask is composed of circular dots having a relatively large diameter and circular dots having a relatively small diameter in the deflection direction of the electron beam by an interval corresponding to the deflection angle of the electron beam. Were spaced apart and struck twice to form a free-standing shape.

Furthermore, the small hole pattern of the second photomask is coaxial with the circular dot on the center side of the first photomask among the circular dots that are twice hit in the large hole pattern of the first photomask. It was formed into a circular shape.

[0018]

When the electron beam passage hole is formed in the above-described shape, the communication portion between the large hole and the small hole, which substantially determines the diameter and shape of the electron beam passage hole, is made circular, and the electron beam passage hole is diagonally crossed. The electron beam is prevented from reflecting toward the phosphor screen when it collides with the side wall of the electron beam passage hole, and the space between the large holes of the adjacent electron beam passage holes is not narrowed. It is possible to prevent a decrease in strength.

When the electron beam passage hole is formed by the above method, the communication portion between the large hole and the small hole, which substantially determines the diameter and shape of the electron beam passage hole, is circular, and the electron beam passage hole is slanted. Sufficient mechanical strength is achieved by preventing the reflection of the electron beam that crosses the electron beam through the side wall of the electron beam passage hole toward the phosphor screen, and without narrowing the gap between the adjacent electron beam passage hole and the large hole. It is possible to stably manufacture a shadow mask having

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 1 shows a shadow mask for a color cathode ray tube which is an embodiment of the present invention. This shadow mask is composed of a mask body 20 and a mask frame 21 attached to a skirt portion formed in the peripheral portion of the mask body 20, and a large number of masks are formed on an effective surface 22 of the mask body 20 facing the phosphor screen. The electron beam passage holes are formed at a predetermined arrangement pitch.

Each of the electron beam passage holes is a communication hole in which a large hole formed on one surface side facing the phosphor screen and a small hole formed on the other surface side communicate with each other. Particularly in the shadow mask of this example, as shown in FIG.
The small hole 24 has a circular shape over the entire effective surface. On the other hand, the large hole 25 differs depending on the position on the effective surface, and has a circular shape at the center of the shadow mask.
The major axis has a peanut shape in which it increases with the deflection angle of the electron beam. The central axis of the small hole 24 is formed so as to be located on the major axis of the large hole 25. In the illustrated example, in particular, the central axis of the small hole 24 is formed inside the peanut-shaped large hole 25 in the deflection direction, that is, at a position that coincides with the central axis of the circular hole on the center side of the shadow mask.

That is, as shown in FIGS. 2A and 2B, the large hole 25 has a central axis Cl at the center of the small hole 24 at the center of the mask body 20 shown by the point A0 in FIG. Although it has a circular shape that coincides with the axis Cs, on the horizontal axis (H axis), the horizontal direction has a major axis as it approaches the horizontal periphery, and the major axis increases according to the deflection angle of the horizontal deflection of the electron beam. Mask body 2 indicated by point AH on 1
0 around the electron beam passage hole on the horizontal axis of FIG.
As shown in (c) and (d), two circular holes of substantially the same size form a peanut shape which is horizontally displaced. The small hole 24 is formed at a position where the central axis Cs of the small hole 24 coincides with the central axis of the circular hole inside the large hole 25 in the deflection direction, and the central axis Cl of the large hole 25 with respect to the central axis Cs of the small hole 24. Are shifted in the horizontal direction, that is, in the major axis direction of the large hole 25.

On the vertical axis (V axis), the longer axis becomes the longer axis as it approaches the periphery in the vertical direction, and the longer axis becomes larger in accordance with the deflection angle of the vertical deflection of the electron beam, as shown by point AV in FIG. As for the electron beam passage hole around the vertical axis of the mask body 20, as shown in FIG. 2E, two circular holes of substantially the same size have a peanut shape in which they are vertically displaced. Then, similarly to the case on the horizontal axis, the small hole 24 is formed at a position where the central axis thereof coincides with the central axis of the circular hole inside the large hole 25 in the deflection direction,
The central axis of the large hole 25 is deviated from the central axis of the small hole 24 in the vertical direction, that is, in the major axis direction of the large hole 25.

Similarly, on the diagonal axis (D axis), the diagonal direction is made longer along the diagonal direction, and the longer diameter becomes larger according to the deflection angle of horizontal and vertical deflection of the electron beam. As for the electron beam passage hole in the peripheral portion of the diagonal axis of the mask body 20 indicated by point AD in FIG.
As shown in (f), two circular holes of approximately the same size form a peanut shape that is diagonally offset. The small hole 24 is formed at a position where the central axis of the small hole 24 coincides with the central axis of a circular hole inside the large hole 25 in the deflection direction, and the central axis of the large hole 25 is opposite to the central axis of the small hole 24. It is displaced in the angular direction, that is, in the major axis direction of the large hole 25.

The electron beam passage hole of such a shadow mask is formed by the photo-etching method like the conventional shadow mask.

That is, as shown in FIG. 3A, a photosensitive film 28 is formed by applying a photosensitizer on both sides of a plate-like member 27 made of a metal plate and drying it. Next, as shown in (b), a pair of negative master plates composed of first and second photomasks 29a and 29b having a pattern for large holes and a pattern for small holes, which will be described later, are formed on the photosensitive film 28 on both surfaces thereof. Exposure is performed in close contact with each other, and photomasks 29a, 29 are formed on the photosensitive films 28 on both sides.
Bake pattern b. Next, the photosensitive film 28 on both sides
Is developed with warm water to remove the unexposed portion, and as shown in FIG. 7C, the electron beam passage hole forming portion is exposed on both surfaces of the plate member 27 corresponding to the pattern of each photomask. Resist films 30a and 30b are formed. Thereafter, a protective film (not shown) is attached to one surface of the plate-shaped member 27 on which the resist films 30a and 30b are formed, on which the resist film 30a is formed, and the other surface on which the resist film 30b is formed. The surface is etched to form small holes 24 on the other surface as shown in FIG. Next, a corrosion inhibitor (not shown) is applied to the other surface where the small holes 24 are formed,
Further, the protective film attached to the one surface is peeled off, and the one surface is etched to form a large hole 25 communicating with the small hole 24 on the one surface, as shown in (e). Form. After that, the resist films 30a and 30b remaining on both surfaces of the plate member 27 are peeled off to obtain a flat flat mask.

Thereafter, the mask body is manufactured by press-molding this flat flat mask into a predetermined shape.

The above-mentioned manufacturing method is a so-called two-step etching method in which the plate member is etched one surface at a time.
This shadow mask can also be manufactured by a simultaneous etching method in which both surfaces of the plate member are simultaneously etched.

Next, the first and second negative master plates of the above pair of negative master plates.
A method of manufacturing the photomasks 29a and 29b will be described.

Photomasks 29 of the pair of negative master plates
Each of a and 29b is manufactured by a photoplotter. As for the small hole pattern of the second photomask 29b, similar to the small hole pattern of the conventional photomask, the small hole circular dot having a size considering the side etching amount is predetermined according to the design of the shadow mask. Produced by plotting on pitch.

The first photomask 29a is manufactured by twice plotting (overlapping) a circular hole dot for a large hole having a size in which the side etching amount is also taken into consideration. That is, as shown in FIG. 4 (a), the large hole pattern 32a at the center of the first photomask has a large hole circular dot at a position corresponding to the small hole pattern 32b at the center of the small hole photomask. It can be obtained by plotting once, but for the pattern for large holes other than the center, the first dot is plotted at the position corresponding to the circular pattern for small holes of the photomask for small holes, and then the deflection direction of the electron beam. It is manufactured by overlapping and striking the second dot with a predetermined shift according to the deflection angle of the electron beam. Figure 4
2B, 2C, and 2D are shown in FIGS.
7E and 7F show patterns corresponding to the electron beam passage holes in the peripheral portions on the horizontal axis, vertical axis, and diagonal axis shown in FIGS. These large hole patterns 32a are formed in a peanut shape having a major axis in the deflection direction of the electron beam, and the major axis direction and the length passing through the centers of the two circular dots of the large hole pattern 32a are plotted positions. Depends on.

In FIG. 4, the large hole pattern 32a and the small hole pattern 32b are drawn in one drawing, but this shows the relative positions of the patterns.
In reality, they are formed separately.

Regarding the production of the first photomask,
The diameter Dxy of the circular dot to be plotted and the deviation amount Δxy between the center of the first dot and the center of the second dot are the position coordinates (position coordinates of the electron beam passage hole of the mask body) for plotting the first dot, respectively. It is changed by Dxy = D0-A · f (x, y) Δxy = Δ00 + B · g (x, y). However, D0 is the diameter of the large hole dot in the center of the photomask, and Δ00 is the amount of deviation between the first dot and the second dot in the center of the photomask. In the photomask of this example, Δ00 = 0 g ( x, y) = g (0,0) = 0.

As a specific example, as shown in FIGS. 4A to 4D, the diameter ds of the small hole dot of the small hole photomask is set to ds = 90 μm, and the center of the large hole photomask is set. The diameter dcl of the large hole dot in is set to dcl = 160 μm, and the long diameter (horizontal diameter) and short diameter (vertical diameter) dHl, dHs of the large hole dot around the horizontal axis, the long diameter around the vertical axis (vertical direction) Diameter) and minor diameter (horizontal diameter) dVl, dVs, major diameter (diagonal diameter) and minor diameter dDl, dDs around the diagonal axis are dHl = 170 μm dHs = 115 μm dVl = 170 μm dVs = 125 μm dDl = 170 μm When dDs = 110 μm, the central large hole diameter of the mask body shown in FIGS. 2A to 2F is Dc, and the large diameter (horizontal diameter) and the short diameter (vertical diameter) of the large holes in the peripheral portion on the horizontal axis. Direction diameter) DHl,
DHs, the long diameter (vertical diameter) and short diameter (horizontal diameter) DVl, DVs in the peripheral portion on the vertical axis, and the long diameter (diagonal diameter) and short diameter DDl, DDs in the peripheral portion on the diagonal axis,
Dc = 250 μm DHl = 260 μm DHs = 205 μm DVl = 250 μm DVs = 210 μm DDl = 260 μm DDs = 205 μm, and the diameter of the large and small holes that determine the shape of the electron beam passage hole is effective. A circular shadow mask having a diameter of 125 μm could be manufactured over the entire surface.

By the way, as described above, the electron beam passage hole of the shadow mask is made to have a major axis in the deflection direction of the electron beam as it approaches the periphery from the center of the shadow mask,
Further, when the peanut-shaped large hole 25 whose major axis increases in accordance with the deflection angle of the electron beam and the small hole 24 whose center is located on the major axis of this large hole 25, the hole shape of the electron beam passage hole is substantially formed. Large hole 25 and small hole 24 that determine
It is possible to make the hole shape of the communicating portion with and circular and to prevent the collision of the electron beam crossing the electron beam passage hole obliquely by the deflection with the side wall of the electron beam passage hole. Further, as shown in FIG. 5, the distance b between the large holes 25 adjacent to each other in the minor axis direction in the peripheral portion of the mask body is smaller than the distance b in the conventional shadow mask shown in FIG. The mechanical strength of the shadow mask can be made sufficiently large.

That is, as a result of molding this shadow mask into a predetermined shape and incorporating it into a color cathode ray tube and evaluating it,
Both the moldability in the molding process and the molding quality were good, and there was no deformation in the color CRT assembly process, and it was possible to obtain a color CRT that does not cause deterioration in color purity due to deformation over the entire screen. In addition, the image quality could be maintained without being deformed by the impact and vibration applied to the color cathode ray tube. Further, even in the peripheral area of the screen, a color cathode-ray tube can be obtained in which the screen quality is not deteriorated due to the reflection on the side wall of the electron beam passage hole.

When the photosensitive films formed on both sides of the plate-like member are exposed, circular dots are shifted according to the deflection angle of the electron beam in the deflection direction of the electron beam, and the circular dots are overprinted twice to form a large hole pattern with peanuts. By using the first photomask 29a having a shape and the second photomask 29b having a small hole pattern as a circle, the hole at the communicating portion between the large hole and the small hole that substantially determines the hole shape of the electron beam passage hole. The electron beam passing through the electron beam passage hole having a circular shape is prevented from reflecting toward the phosphor screen when the electron beam obliquely crosses the side wall of the electron beam passage hole, and between the large holes 25 of the adjacent electron beam passage holes. The effect of being able to widen the distance b and to easily and stably manufacture a shadow mask having sufficient mechanical strength is obtained.

Although the large holes of the shadow mask are peanut-shaped in the above-mentioned embodiment, the large holes have a small displacement between two dots of the large-hole photomask, and the shadow mask is manufactured. When the etching amount is large, the shape becomes oval.

Further, in the above-described embodiment, the large hole on one surface side facing the phosphor screen is composed of two circular holes of substantially the same size which are displaced in the deflection direction of the electron beam, but different from FIG. A large hole shape is shown. That is, the electron beam passage hole of the shadow mask of this example has a circular hole 34 having a relatively large diameter with respect to the large hole 25 on one surface side, and a relative relative to the circular hole 34, which is displaced outward in the deflection direction of the electron beam. And a circular hole 35 having a small diameter, so that the small hole 24 on the other surface side is located on the major axis of the large hole 25. Particularly in the illustrated example, the central axis of the small hole 24 is the large hole 25.
Is formed at a position coinciding with the central axis of the large circular hole 34.

The electron beam passage hole of this shadow mask also has a large hole 25 as shown in FIGS. 6 (a) and 6 (b).
In the center of the mask body, the central axis Cl is a small hole 24.
Although it has a circular shape that coincides with the central axis Cs of the mask, on the horizontal axis, the horizontal direction has a major axis as it approaches the horizontal periphery, and the major axis increases with the deflection angle of the horizontal deflection of the electron beam. As for the electron beam passage hole in the peripheral portion on the horizontal axis, as shown in FIGS. 6C and 6D, a circular hole 35 having a relatively small diameter with respect to a circular hole 34 having a relatively large diameter is used. Has a horizontal misalignment. The small hole 24 is formed at a position where the central axis Cs of the small hole 24 coincides with the central axis of the circular hole 34 having a relatively large diameter on the inner side of the large hole 25 in the deflection direction, and with respect to the central axis Cs of the small hole 24. The central axis Cl of the large hole 25 is displaced in the horizontal direction, that is, the major axis direction of the large hole 25.

On the vertical axis, the vertical direction has a longer diameter as it approaches the periphery of the vertical direction, and the longer diameter increases with the deflection angle of vertical deflection of the electron beam, and the electron beam passes around the periphery of the vertical axis of the mask body. For holes,
As shown in FIG. 6E, a circular hole 34 having a relatively large diameter is formed.
The circular hole 35 having a relatively small diameter has a vertical offset shape. And like the case on the horizontal axis,
The small hole 24 is formed at a position where its central axis coincides with the central axis of a relatively large circular hole 34 on the inner side of the large hole 25 in the deflection direction. The central axis of is shifted in the vertical direction, that is, in the major axis direction of the large hole 25.

Similarly, on the diagonal axis, the diagonal direction is made longer as it approaches the periphery of the diagonal direction, and the longer diameter becomes larger according to the deflection angle of horizontal and vertical deflection of the electron beam, and the diagonal of the mask main body is obtained. As for the electron beam passage hole in the peripheral portion of the shaft, as shown in FIG. 6F, the relatively small circular hole 35 is diagonally displaced from the relatively large circular hole 34. Make a Daruma shape. The small hole 24 is formed at a position where its central axis coincides with the central axis of a relatively large circular hole 34 inside the large hole 25 in the deflection direction.
The central axis of the large hole 25 is displaced from the central axis of 4 in the diagonal direction, that is, in the major axis direction of the large hole 25.

The electron beam passage hole of such a shadow mask has a large hole pattern corresponding to the large hole 25 formed on one surface of the plate member by the photo-etching method similarly to the shadow mask of the above-mentioned embodiment. Is formed using the first photomask having the above-described structure and the second photomask having the pattern for small holes corresponding to the small holes 24 formed on the other surface of the plate-shaped member.

As for the second photomask, the photomask has circular dots for small holes having a size considering the side etching amount according to the design of the shadow mask, similar to the pattern for small holes of the conventional photomask. It is manufactured by plotting at a predetermined pitch. The first photomask is manufactured by stacking a circular dot having a relatively large diameter and a circular dot having a relatively small diameter in the same size in consideration of the side etching amount.

That is, as shown in FIG. 7A, the first
The large hole pattern 32a at the center of the photomask is obtained by once plotting a circular dot 36a having a relatively large diameter at a position corresponding to the central hole pattern at the small hole photomask. For other large hole patterns, a circular dot 36a (first dot) having a relatively large diameter is plotted at a position corresponding to the small hole circular pattern of the small hole photomask, and then the electron beam deflection direction is plotted. It is manufactured by repeatedly striking circular dots 36b (second dots) having a relatively small diameter with a gap corresponding to the deflection angle of the electron beam. 7 (b), (c), and (d) show the electron beam passage holes at the peripheral portions on the horizontal axis, the vertical axis, and the diagonal axis shown in FIGS. 6 (c), (e), and (f), respectively. The corresponding patterns are shown. These large hole patterns 32
a is a large and small circular dot 3 in the deflection direction of the electron beam
6a and 36b are formed separately, and the major axis passing through the centers of the two circular dots 36a and 36b of the large hole pattern 32a varies depending on the plotted position. Further, the center of the circular dot 36a is located at the same position as the center of the circular dot of the circular pattern for small holes (not shown).

The circular dot 36 having a relatively large diameter is used.
As shown in FIG. 8, the deviation amount and the angle of the circular dot 36b having a relatively small diameter with respect to a are as follows.
The distance L between a and the small-diameter circular dot 36b is adjusted according to the deflection angle, and the small-diameter circular dot 36b is rotated about the large-diameter circular dot 36a by an angle corresponding to the deflection direction of the electron beam. It is obtained by

By the way, as described above, the electron beam passage hole of the shadow mask is made to have a major axis in the deflection direction of the electron beam from the center of the shadow mask toward the periphery.
Moreover, when the large hole 25 having a daruma shape whose major axis increases according to the deflection angle of the electron beam and the small hole 24 whose center is located on the major axis of the major hole 25, the electron is substantially larger than that in the above embodiment. The communication portion between the large hole 25 and the small hole 24 that determines the hole shape of the beam passage hole can be made into a good circular shape, and the electron beam passage hole side wall of the electron beam that obliquely crosses the electron beam passage hole by deflection can be formed. The collision of can be effectively eliminated. Moreover, as shown in FIG. 9, the distance between the large holes 25 adjacent to each other in the peripheral portion of the mask body is also
The distance between the circular holes 35 having a relatively small diameter can be made larger than the distance b in the shadow mask of the embodiment shown in FIG. 5 and the mechanical strength of the shadow mask can be increased. Can be As a result, it is possible to obtain a color CRT that does not cause deterioration in color purity due to the deformation of the shadow mask, does not undergo deformation by impact or vibration, and maintains good image quality.

[0049]

EFFECTS OF THE INVENTION An electron beam passage hole consisting of a large hole formed on one surface side of a plate member and a small hole formed on the other surface side of the plate member is moved from the center of the shadow mask to the periphery thereof. According to the direction of deflection of the electron beam as a major axis, this major axis has a peanut shape or an oval shape or a daruma shape that increases according to the deflection angle of the electron beam, the small hole has a circular shape, and the center of this small hole is the large hole. When formed in a shape positioned on the long axis, the communication part between the large hole and the small hole that substantially determines the hole shape of the electron beam passage hole can be made circular, and the electron beam passage hole can be diagonally crossed. It is possible to prevent reflection in the direction of the phosphor screen caused by the electron beam colliding with the side wall of the electron beam passage hole, and it is possible to widen the distance between the adjacent electron beam passage hole and the large hole. It is possible to prevent a reduction in 械的 strength.

When the shadow mask is manufactured, circular dots having substantially the same size are shifted in the deflection direction of the electron beam according to the deflection angle of the electron beam, and the dots are overlapped twice to form a large hole pattern into a peanut shape. Alternatively, the relatively large dots and the relatively small dots are staggered and hit twice to make the large hole pattern a duller-shaped first photomask and the small hole pattern have a circular shape. When the electron beam passage hole is formed in the plate-like member using the second photomask, the communication portion between the large hole and the small hole, which substantially determines the hole shape of the electron beam passage hole, is circular, and the electron beam passage hole is formed. Prevents reflection in the phosphor screen direction caused by the electron beam crossing diagonally colliding with the side wall of the electron beam passage hole,
Moreover, the distance between the adjacent electron beam passage hole and the large hole can be widened, and a shadow mask having sufficient mechanical strength can be stably manufactured.

Particularly, when the first photomask in which the pattern for large holes has a duller shape and the second photomask in which the pattern for small holes has a circular shape are used, the communicating portion between the large holes and the small holes becomes a good circle, In addition, a shadow mask having sufficient mechanical strength can be manufactured extremely stably.

[Brief description of drawings]

FIG. 1 is a plan view for explaining a shadow mask of the present invention.

2 (a) is a plan view showing a central electron beam passage hole of a mask body in which a large hole on one surface side of the electron beam passage hole has a peanut shape, and FIG. 2 (b) is a sectional view thereof. 2 (c) is a plan view showing electron beam passage holes in the peripheral portion on the horizontal axis, and FIG. 2 (d) is a sectional view thereof.
2E is a plan view showing electron beam passage holes in the peripheral portion on the vertical axis, and FIG. 2F is a plan view showing electron beam passage holes in the peripheral portion on the diagonal axis.

FIG. 3A to FIG. 3E are views for explaining a method for manufacturing the shadow mask.

FIG. 4 (a) is a diagram showing a central pattern of a photomask used for manufacturing a mask body, FIG. 4 (b) is a diagram showing a peripheral pattern on a horizontal axis, and FIG. 4 (c). FIG. 4A is a diagram showing a peripheral portion pattern on a vertical axis, and FIG. 4D is a diagram showing a peripheral portion pattern on a diagonal axis.

FIG. 5 is a diagram for explaining a distance between electron beam passage holes of a shadow mask in which the large holes have a peanut shape.

FIG. 6A is a plan view showing an electron beam passage hole in the center of a mask body in which a large hole on one surface side of the electron beam passage hole of a shadow mask has a dulled shape; FIG. 6C is a cross-sectional view, FIG. 6C is a plan view showing electron beam passage holes in the peripheral portion on the horizontal axis, and FIG. 6D is a cross-sectional view thereof.
6 (e) is a plan view showing electron beam passage holes in the peripheral portion on the vertical axis, and FIG. 6 (f) is a plan view showing electron beam passage holes in the peripheral portion on the diagonal axis.

FIG. 7 shows a large hole pattern for forming electron beam passage holes of the shadow mask shown in FIG. 6, and FIG.
Is a diagram showing a central pattern of a photomask used for manufacturing the mask main body, FIG. 7B is a diagram showing a peripheral portion pattern on the horizontal axis, and FIG. 7C is a peripheral portion pattern on the vertical axis. FIG. 7D is a diagram showing the pattern, and FIG. 7D is a diagram showing the pattern of the peripheral portion on the diagonal axis.

FIG. 8 is a diagram for explaining a method of manufacturing the photomask.

FIG. 9 is a diagram for explaining a distance between electron beam passage holes of a shadow mask in which the large holes have a dulled shape.

FIG. 10 is a diagram showing a configuration of a color Braun tube.

11A is a plan view showing the configuration of the shadow mask, and FIG. 11B is a sectional view thereof.

FIG. 12 is a sectional view showing a basic shape of the electron beam passage hole.

13A is a plan view showing an electron beam passage hole in the center of a mask body of a conventional shadow mask, FIG.
13B is a sectional view thereof, FIG. 13C is a plan view showing electron beam passage holes in the peripheral portion on the horizontal axis, and FIG.
Is a sectional view, FIG. 13 (e) is a plan view showing electron beam passage holes in the peripheral portion on the vertical axis, and FIG. 13 (f) is a plan view showing electron beam passage holes in the peripheral portion on the diagonal axis. is there.

FIG. 14 is a view showing a shape of a communicating portion between a large hole and a small hole of an electron beam passage hole of the conventional shadow mask.

FIG. 15 is a diagram for explaining an interval between electron beam passage holes of the conventional shadow mask.

[Explanation of symbols]

 20 ... Mask main body 22 ... Effective surface 24 ... Small hole 25 ... Large hole 27 ... Plate member 28 ... Photosensitive film 29a ... First photomask 29b ... Second photomask 30a, 30b ... Resist film 32a ... Large hole pattern 32b ... Small hole pattern 34 ... Relatively large circular hole 35 ... Relatively small circular hole

Claims (6)

[Claims] 1. A large hole formed on one surface side of the plate member and a plurality of small holes formed on the other surface side of the plate member having a large number of electron beam passage holes formed at a predetermined arrangement pitch in the plate member. In the shadow mask for a color cathode-ray tube consisting of and, the electron beam passage hole is such that the direction of deflection of the electron beam becomes longer as the large hole approaches the periphery from the center of the shadow mask, and this longer diameter becomes larger according to the deflection angle of the electron beam. A color cathode-ray tube characterized by having a peanut shape, an oval shape or a daruma shape, wherein the small hole has a circular shape, and the center of the small hole is formed on the major axis of the large hole. Shadow mask. 2. The shadow mask for a color cathode ray tube according to claim 1, wherein the peanut-shaped, oval-shaped, or daruma-shaped electron beam passage hole comprises at least two overlapping circular holes, and the electron beam passage hole has a small hole. Is formed coaxially with the large hole of the circular holes located on the center side of the shadow mask among the two circular holes. 3. A photosensitive film is applied and formed on both surfaces of the plate member,
The photosensitive films on both sides are exposed and developed through a first photomask on which a pattern for large holes is formed and a second photomask on which a pattern for small holes is formed. A resist film consisting of a pattern corresponding to the mask pattern is formed, and the plate-shaped member on which the resist film is formed is etched from both sides to form a large hole on one side of this plate-shaped member and a small hole on the other side. In the method of manufacturing a shadow mask for a color cathode ray tube in which a hole is formed to form an electron beam passage hole, the large hole pattern of the first photomask is formed in a direction corresponding to a deflection angle of the electron beam in a deflection direction of the electron beam. For the small holes of the second photomask, the center positions of the circular dots are shifted twice and the circular dots are hit twice to form a pattern in which the circular dots partially overlap or are separated from each other. A method for manufacturing a shadow mask for a color cathode ray tube, wherein the pattern is circular and the electron beam passage holes are formed in the plate-like member using the first and second photomasks. 4. The method for manufacturing a shadow mask for a color cathode ray tube according to claim 3, wherein the large hole pattern of the first photomask is formed of circular dots at intervals corresponding to the deflection angle of the electron beam in the deflection direction of the electron beam. A method for producing a shadow mask for a color cathode-ray tube, comprising forming a peanut shape by hitting the center position twice. 5. The method for manufacturing a shadow mask for a color cathode ray tube according to claim 3, wherein the large hole pattern of the first photomask is relatively arranged in the deflection direction of the electron beam by an interval corresponding to the deflection angle of the electron beam. A method for producing a shadow mask for a color cathode-ray tube, comprising forming circular dots having a large diameter and circular dots having a relatively small diameter separately and striking them twice to form a free-form shape. 6. The method for manufacturing a shadow mask for a color cathode-ray tube according to claim 3, wherein the small hole pattern of the second photomask is the large hole pattern of the first photomask. A method for manufacturing a shadow mask for a color cathode ray tube, comprising forming circular dots coaxial with the circular dots on the center side of the first photomask among the circular dots to be beaten.