JPH01175148A - Shadow mask - Google Patents

Abstract

PURPOSE:To eliminate distortion and obtain a good-quality screen by forming the opening shape on the large hole side located on the display side of each hole into a shape protruded arc-wise outwardly for at least one or more end sections of long sides. CONSTITUTION:To prevent an electron beam with an angle from being cut off, the opening shape on the large hole side of a shadow mask is formed in a shape protruded arc-wise outwardly at both ends or one end of both long sides of a rectangle. A through hole having a large hole diameter and protruded arc-wise outwardly at both ends of both long sides is formed, with the thickness on the large hole side: 0.25mm, slot length L1: 700mm, main slot width S1: 0.19mm, large hole diameter R: 0.50mm, distance S'' to the top: 0.1mm, vertical distance L' of protruded section: 0.1mm. Many through holes are aligned at the vertical distance M1: 0.825mm and the horizontal distance M2: 0.95mm to obtain the shadow mask, and an electron beam shape shown in the figure can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to shadow masks used in various display devices such as CRTs and color televisions.

<Conventional technology> The conventional technology will be briefly explained.

FIG. 4 is a partial plan view of a conventional conventional shadow mask. 5 is a partial sectional view taken along line A, FIG. 6 is a partial sectional view taken along line B, and FIG. 7 is a partial sectional view taken along line C.

Conventional shadow masks have thicker walls at the edges. If an electron beam enters obliquely in such a shadow mask, even if it enters from the small hole side located on the electron gun side, it will be reflected by the thick part and will not pass through.

Therefore, the electron beam transmission pattern particularly at the outer edge of such a shadow mask is a pattern that is missing at the outer edge, as shown in FIG.

<Problems to be Solved by the Invention> In the shadow mask as described above, even if light enters from the small hole side, it will be reflected by the thick portion and will not be transmitted.

Therefore, the electron beam transmission pattern of such a shadow mask, particularly at the outer edge, becomes a missing pattern at the outer edge.

Therefore, there is a considerable difference in brightness between the center and end portions of the shadow mask.

In order to compensate for this brightness, as shown in Figure 9, the shadow mask can be improved by increasing the width of the hole, narrowing the middle of the bridge, making the rectangular shape of the hole more rectangular (rectangular shape), etc. However, due to the following reasons, it is difficult to adopt
It has no practical effect.

(1) When the width of the through hole is widened, when creating the fluorescent screen surface, a photosensitive resin containing phosphor is applied, exposed and developed through a mask, and then developed.
A phosphor screen is made by forming a green phosphor pattern, but if the width of the through hole is wide, a phosphor screen will be formed in which the three types of phosphor overlap, or the phosphor screen will not overlap. Even if the phosphor pattern is formed just in time, the phosphor pattern to be emitted by the electron beam and the phosphor pattern adjacent thereto are likely to be colored.

(2) The method of narrowing the bridge reduces the mechanical strength of the shadow mask, making it more likely that the shadow mask will stretch or deform during press molding, or cause color shift due to thermal deformation due to electron beam irradiation. .

(3) If the arrangement interval (pitch) of the through holes is made finer, (1
The same problem as in 1 will occur if the width of the through hole is widened.

(4) In the method of making the hole rectangular, it is true that the transmittance is high when viewed from the front, but since the electron beam is irradiated at a certain angle at the four corners of the color cathode ray tube, the large hole side Part of the electron beam is not transmitted, resulting in an electron beam transmission shape as shown in FIG.

In addition, a shadow mask with one or more long sides protruding outward in an arc shape on the side of the small hole was developed in U.S. Pat. No. 55-1387.
It is publicly known from Publication No. 57. However, even if an arcuate protrusion is provided on the side of the small hole as in this publication, the above-mentioned problems cannot be solved.

<Means for Solving the Problem> In the present invention, in order to prevent an angled electron beam from being blocked, changing the small hole side is less effective, and changing the large hole side is less effective. It was discovered and invented that it is highly effective. That is, the shape of the opening on the large hole side of the shadow mask is a rectangular shape with both ends or one end of both long sides protruding outward in an arc shape.

In such a shadow mask, the opening shape of the large hole on the phosphor side is rectangular with both ends of both long sides or the end facing outward from the center of the mask protruding outward in an arc shape. In addition,
The arc shape according to the present invention does not mean only a complete circular arc, but also includes a curved shape that is proximally similar to a circular arc.

Further, the distance S' from the top of the protruding portion opposite to the main slot width SI of the large hole portion satisfies Sl>S' and is desirably 18 to 1 times the plate thickness.

<Function> When a shadow mask such as that of the present invention is used, most of the electron beam incident from the small hole side penetrates to the large hole side, and it is possible to do so without distortion and without changing the aperture ratio too much.

<Examples> Examples of the present invention will be described in detail. FIG. 1 is a plan view of this embodiment. By etching a thin metal plate, the large hole side has a plate thickness of 25 mm and a front length L0° of 700 m.
m Main slot Main slot width 190mm, large hole diameter R0,5
00mm, the corresponding distance to the top of the protrusion S'0
．． 100mm, vertical distance of protrusion L' 0.10
It is a through hole with a large diameter in the shape of a 0+nm rectangle with both long sides protruding outward in an arc shape, and it has a vertical spacing of M10.
．． A large number of shadow masks were obtained with a width of 825 mm and a horizontal interval MtO of 950 mm. In this example, an electron beam shape as shown in Fig. 2 can be obtained, and the transmittance in the oblique direction was measured, and the vertical transmittance of the conventional product was 20.
9%, the transmittance of the same product at an oblique light angle of 23° is 19.4%
In this example, the transmittance at an oblique light angle of 23° was 20.5%.

Another example is shown in FIG. 3. In this case, a shadow mask having arcuate protrusions having the same values as those described above only at the ends toward the outside from the center of the shadow mask was used. I was able to obtain

<Effects of the Invention> When a shadow mask such as that of the present invention is used, almost all of the electron beam incident from the small hole side is transmitted to the large hole side. As a result, the transmitted beam pattern has a shape that is advantageous for display, eliminates distortion, and provides a high-quality screen.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a plan view showing an embodiment of the present invention.
FIG. 3 is a plan view showing another embodiment of the electron beam transmission shape. 4 is a plan view showing the conventional example, FIG. 5 is a cross-sectional view taken along line A, FIG. 6 is a cross-sectional view taken along line B, FIG. 7 is a cross-sectional view taken along line C, and FIG. The figure shows the same electron beam transmission shape, FIG. 9 is a plan view showing another conventional example, and FIG. 10 shows the same electron beam transmission shape. l...Large hole side opening shape 2...Small hole side opening shape 3...Electron beam transmission shape Figure 2 Figure 3 Tsukuda 9 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Scope of Claims] 1) A shadow mask in which the opening shape of the large hole located on the display side of each hole is such that at least one or more of the long sides thereof protrudes outward in an arc shape. 2) The shadow mask according to claim 1, characterized in that there are arcuate protrusions at both ends of both long sides. 3) The shadow mask according to claim 1, characterized in that there is an arcuate protrusion at an end portion extending outward from the center of the shadow mask.