JPH0410335A - Shadow mask and its manufacture - Google Patents

Abstract

PURPOSE:To pass electron beam sufficiently and at the same time to prevent holes from communicating each other by making holes in the front side almost elliptical and holes in the back side circular, and bringing the longitudinal direction of the front side holes into harmony with the proceeding direction of the electron beam. CONSTITUTION:While holes in the back side are circular, the shapes of holes 1 in the front side are almost elliptical in radial direction. The major axis of the almost elliptical holes 1 in the front side is brought into harmony with the center direction of a shadow mask. That is, the longitudinal direction of the front side holes 1 is brought into harmony with the proceeding direction of electron beam. Consequently, the roundness of the through holes is maintained and at the same time since unnecessary parts in conventional circular shapes in the front side are prevented from corroding, the whole of the mask becomes firm. As a result, the holes are prevented from communicating each other and at the same time electron beam is passed efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dot-type shadow mask mainly used for displays and a method for manufacturing the same.

[Prior Art] Fig. 5 is a diagram showing the overall structure of a dot-type shadow mask (hereinafter simply referred to as a shadow mask). and a skirt portion 13. Perforated part 1
The electron beam passing through the second through hole is incident straight at the center, but becomes obliquely incident toward the outer periphery. Therefore, the dots of a conventional shadow mask have a structure as shown in FIG. FIG. 6 is a plan view of the dots seen from the front side of the shadow mask 11, that is, from the screen side.
As shown in FIG. 6(a), the dot shape of a part of the center of the dot 14 is such that a through hole 15 opened in the center of the dot 14 is etched larger toward the front side, and a tapered portion 16 is formed. . Further, FIG. 6(b) is a diagram showing the shape of a dot located on the outer periphery of the X axis indicated by A1 in FIG.
The same figure (C) shows the shape of the dot located on the outer periphery of the Y axis indicated by A2 in Fig. 5, and the same figure (d) shows the shape of the dot located on the outer circumference of the diagonal axis indicated by A2 in Fig. 5. At these positions, the electron beam 18 passes obliquely to the shadow mask 11, so the front pattern for plate making used when manufacturing the shadow mask is shifted in the radial direction, and the taper in the outer circumferential direction of the shadow mask is created. The width is increased so that the electron beam 18 can pass through the shadow mask 11 smoothly. An example of a cross section of these dots 14 is shown in FIG. Fig. 7(a) shows the cross-sectional shape of the dot shown in Fig. 6(a), and Fig. 7(b) shows the cross-sectional shape of the dot shown in Fig. 6(b).
The cross-sectional shape of the dot shown in is shown. In addition, in Fig. 7, 20 is the front side, 21 is the back side, φ is the front hole diameter, and 11 is the front side hole diameter.
I indicates the outer Taber width, and 9□ indicates the inner Taber width.

[Problem to be solved by the invention] In recent years, color cathode ray tubes for displays have become increasingly high-definition, bright, and flat-faced.
Along with this, there is a tendency for the pitch of the through holes and the hole diameter of the through holes of shadow masks to both become finer. Furthermore,
As the brightness of cathode ray tubes increases, color shift or screen shaking due to doming caused by thermal expansion of the shadow mask during light emission has become a problem. As a countermeasure,
Consideration is being given to making the shadow mask material thicker and using Invar material, which is an alloy of iron and nickel that does not easily expand thermally. In addition, when designing a shadow mask, see Figure 7 (a).
) is the hole diameter φ on the screen side surface. Measures are taken to make the volume of the material after etching as small as possible (by pressing it down to make the volume of the material larger after etching), and to maintain the mechanical strength of the shadow mask.

Furthermore, as cathode ray tubes have become flat-faced, shadow masks have been designed to allow electron beams to pass through the shadow mask even if the electron beam passing through the shadow mask is tilted in the radial direction at the outer periphery of the shadow mask to a greater extent than before. There has been a demand for what must be done. Therefore, in the outer periphery of the shadow mask, as shown in Fig. 7(b),
The outer taper width on the screen side shown in 9. is made larger than before.

By the way, it has been found that the following problem occurs when a thicker fine pitch shadow mask is manufactured using the conventional shadow mask manufacturing pattern which is circular on both the front and back sides.

That is, when etching a thick material, the depth of etching in the vertical direction not only increases the amount of etching in the vertical direction, but also increases the amount of side etching in the lateral direction. Therefore, in the fine pitch mask, the 8th
As shown by B in the figure, there is a problem in that adjacent holes are likely to connect with each other at a taper portion of 1θ, and as a result, the strength of the shadow mask decreases. This is particularly noticeable in the vertically tapered portion of the outer periphery of the shadow mask. This is because, as shown in Fig. 9, in the center part of the shadow mask, the pitches P+, Pa, and P'a in each direction are all equal in an equilateral triangular array, but as you move toward the outer periphery in the X-axis direction, the pitch P increases. This is because the array is decreasing.

In addition, in FIG. 8, 23 indicates the side etching direction.

Such connections between holes can be easily prevented by reducing the hole diameter φg on the surface of the shadow mask. Therefore, in order to reduce the surface hole diameter φe and increase the outer taper width 9 at the outer periphery of the shadow mask, it is necessary to increase the amount of displacement of the front pattern in the radial direction. Figure 10(a)
Furthermore, the through hole 15 when viewed from the front side has a shape that is collapsed in one direction as shown in FIG.

The present invention solves the above-mentioned problems, and aims to provide a shadow mask that can sufficiently pass an electron beam and prevent holes from connecting with each other, and a method for manufacturing the same. It is something.

[Means for Solving the Problems] In order to achieve the above object, in the shadow mask of the present invention, the front hole has a substantially elliptical shape, the back hole has a circular shape, and the longitudinal direction of the front hole is parallel to the electron beam. The size of the front hole and the center positions of the front hole and the back hole are aligned with the direction of electron beam travel.

In addition, the method for manufacturing a shadow mask of the present invention uses a front side hole pattern plate consisting of a polygonal pattern made longer in one direction and a circular back hole pattern plate to apply resist applied to both sides of a steel plate from both sides. It is characterized by including a plate-making process of developing the resist after exposure, and the front side hole pattern plate has a variable aperture arranged in a pattern exposure machine that is long and approximately elliptical in one direction, and the aperture is rotated. It is characterized in that it is created by specifying its longitudinal direction and drawing it with a pattern exposure machine.

[Operations and Effects of the Invention] In the shadow mask of the present invention, the front side hole is approximately elliptical and the rear side hole is circular, so the shape is elongated to match the traveling direction of the electron beam, and the through hole is perfectly circular. In addition to ensuring strength, unnecessary parts of the conventional circular front surface are not corroded, so the entire mask can be made stronger. It is also possible to prevent connections between holes.

Furthermore, since the size of the front side hole, the center position of the front and back holes, and the center position of the back side hole are aligned with the traveling direction of the electron beam, the electron beam can be transmitted efficiently.

The front hole pattern plate used in the shadow mask manufacturing method of the present invention has a hexagonal shape,
A polygonal variable aperture such as a square is drawn as a substantially elliptical shape by elongating one direction to create it, but variable apertures in polygonal shapes such as hexagons and octagons are already in practical use, so it is easy to create. can be created.

Furthermore, since the longitudinal direction of the polygon is designated by rotating the aperture in the exposure machine, this can be easily done.

[Example code] Examples will be described below with reference to the drawings.

While the oblong shape of the front side of the conventional shadow mask is circular as shown in FIG. 6, the shadow mask of the present invention has a circular hole on the back side as shown in FIG. As shown, the shape of the front side hole 1 is approximately elliptical in the radial direction. That is, the long sleeve of the substantially elliptical front hole is aligned with one direction toward the center of the shadow mask. In other words, the longitudinal direction of the front hole is made to coincide with the traveling direction of the electron beam.

The length Dl in the major axis direction and the length D2 in the minor axis direction are determined according to the traveling direction of the electron beam. In other words, it is determined by the position of the hole on the shadow mask. That is, in the center part of the shadow mask, =D
2, that is, it is circular, but at the outer periphery D + > D a
It is done. In this way, not only can the outer taper width Q1 of the dots be increased, but also the vertical distance between adjacent front side holes 1 is wider than before, as shown by d in FIG. It is possible to prevent the holes from connecting with each other at some points, thereby preventing a decrease in strength due to the connections between the holes.

Furthermore, the center position of the pattern on the front side hole, which has a substantially elliptical shape, with respect to the back side hole is shifted in accordance with the traveling direction of the electron beam. That is, the center of the pattern in the front hole is located at the center of the back hole in a portion of the shadow mask center, but as it goes toward the outer periphery, it is positioned closer to the outside of the shadow mask, that is, shifted in the radial direction.

When the shape of the front side hole is made as above, the outer taper width is 9.
Since TI and T2 shown in FIG. 1 can be made small even when the etching is increased, the volume of the material after etching can be increased.

Therefore, it is effective in countering thermal expansion of the shadow mask and further improving the strength of the shadow mask.

Next, a method for manufacturing the above-mentioned shadow mask will be explained.

First, a front hole pattern plate for plate making is prepared in a polygonal pattern such as a hexagon as shown in FIG. 3(a) or an octagon as shown in FIG. 3(b). That is, a polygonal variable aperture provided in an exposure machine is made into a substantially elliptical shape elongated in one direction, and a glass dry plate coated with a photoreceptor is exposed by setting the width W and height H according to the position of the hole. do. At this time, as described above, it is necessary to make the shape of the surface hole obtained as a result of etching into an elliptical shape in the radial direction, but this is done by rotating the aperture and specifying the longitudinal direction.

Next, the glass dry plate is developed. This yields a front hole pattern plate.

The back hole pattern plate for plate making is created using a circular pattern in the same way as in the past.

After creating the front hole pattern plate and the back hole pattern plate in this way, next, use the front hole pattern plate on one side of the steel plate coated with resist on both sides, and create the front hole pattern on the other side. Each back hole pattern is exposed using a back hole pattern plate, and then development, hardening, and boss baking are performed to make the plate.

After these treatments, the steel plate is etched on both sides simultaneously or on one side at a time using a corrosive solution. Thereby, the shadow mask described above can be obtained.

In fact, as shown in FIG.
For a steel plate with a thickness of 5wn, the width of the hole on the front side is w = x
3ottmz K = 110 μm Octagonal pattern 2 is used on one side, and circular pattern 5 is used on the other side for the back hole, development, hardening, and post baking are performed. After processing, when this is etched, the length in the long sleeve direction D + = 25
A front side hole 4 having a substantially elliptical shape in the radial direction with a length D2 in the short axis direction of 230 μm was obtained. It was confirmed that there was no connection between adjacent holes in the Nyadou mask created in this way, and sufficient electron beam passage was observed. In FIG. 4, the shaded area indicated by 8.9 indicates a resist film, and 7 indicates a through hole formed by etching.

Although the embodiments of the present invention have been described above, it is clear to those skilled in the art that the present invention is not limited to the above embodiments, and that various modifications can be made.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the hole shape of the shadow mask according to the present invention, FIG. 2 is a diagram showing the relationship between adjacent holes, and FIG. 3 is an example of the pattern shape used in manufacturing the Nyadu mask of the present invention. FIG. 4 is a diagram for explaining the method of manufacturing a shadow mask according to the present invention, FIG. 5 is a diagram showing the overall structure of the shadow mask, and FIG. 6 is a plan view of dots of a conventional shadow mask. , FIG. 7 is a cross-sectional view of dots in a conventional shadow mask, FIG. 8 is a diagram for explaining the connection between adjacent holes, FIG. 9 is a diagram showing the arrangement of holes in a shadow mask, and FIG. 10 is a diagram for explaining the connection between adjacent holes. FIG. 3 is a diagram showing a long shape of a Nyadou mask with an excessively thick outer taper. 1... Front side hole, 2... Front side general purpose octagonal pattern, 3
...Front side resist part shape after plate making, 4...Front side hole,
5... Back side substitute circular pattern, 6... Back side resist part shape after plate making, 7... Through hole, 8.9... Resist film, Process 1... Shadow mask, 12... Existence hole,
13...Skirt part. Applicant Dai Nippon Printing Co., Ltd. Agent Patent attorney Hideo Sugai (7 others) Figure 4 Figure 5 Y-axis giG diagram (a) (b) (c) (d) (a) Figure 7 ( b) 8th yJ

Claims (4)

[Claims] (1) A shadow mask characterized in that the front hole has a substantially elliptical shape, the back hole has a circular shape, and the longitudinal direction of the front hole coincides with the traveling direction of the electron beam. (2) The shadow mask according to claim 1, wherein the size of the front side hole and the center positions of the front side hole and the back side hole are aligned with the traveling direction of the electron beam. (3) A plate-making process in which the resist coated on both sides of the steel plate is exposed from both sides using a front-side hole pattern plate consisting of a polygonal pattern made longer in one direction and a circular back-hole pattern plate, and then the resist is developed. A method for producing a shadow mask, comprising: (4) The front hole pattern plate has a variable aperture installed in a pattern exposure machine that is long and approximately elliptical in one direction, and the longitudinal direction is specified by rotating the aperture. 4. The method of manufacturing a shadow mask according to claim 3, wherein the shadow mask is created by drawing.