JPS61168841A - Shadow mask for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To get rid of unevenness and discrepancy in color by providing a bottomed groove and circular holes between the small diameter holes on the side of an electron gun in the aperture region. CONSTITUTION:The large diameter holes 6 are provided on the fluorescent screen side in the aperture region 4 while providing the small diameter holes 7 on the side of an electron gun and forming the circular holes 5 on the part where the holes 6 and 7 intersect. Then, a groove 8 is provided between the neighboring small diameter holes 7 on the side of the electron gun. When the groove 8 is provided in this way, compressive stress to be generated on the screen on the side of the electron gun when press molding can be reduced. Accordingly, positional fluctuation of the holes 5 after a thermal is reduced while reducing mislanding so as to get rid of unevenness and discrepancy in color.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shadow mask for a color cathode ray tube having a large number of circular apertures.

(Prior art and its problems) In general, a shadow mask for color cathode ray tubes having circular apertures is a flat shadow mask plate consisting of a perforated area having a large number of circular apertures and a non-perforated area around the perforated area. It is formed by press molding into a curved surface 2 and a skirt portion 3 bent around the two curved surfaces 2 at approximately right angles to the curved surface 2 as shown in FIG. 113.

Here, the shape of the first curved surface 2 is an arbitrary curved surface and is not limited to a spherical shape, etc., and the perforated region 4 is included in this curved surface 2, and the outer peripheral part of the first curved surface 2 is non-porous. It is an area.

'Ir4 diagram (a) shows the circular aperture 5t- in the perforated region 4.
It is a front view seen from the convex side of the curved surface 2, that is, the fluorescent surface side.

Straight line! -! FIG. 4(b) is a cross-sectional view taken along the line '.

As shown in FIG. 4, the perforated region 4 has large diameter holes 6. There is a small diameter hole 7 on the electron gun side, and a circular hole 5 is formed at the intersection of the large diameter hole 6 and the small diameter hole 7. In FIG. 4, the small-diameter hole 7 and the circular aperture 5 are distinguished, but there are cases where the small-diameter hole and the circular aperture coincide, making it impossible to distinguish between them.

When a flat shadow mask plate is press-molded into the shape shown in the t-IEB diagram and the rectangle 4 diagram, compressive stress is generated on the electron gun side surface of the shadow mask.

When this compressive stress is large, press forming may not be carried out sufficiently, resulting in problems such as bending of the perforated region 4 or inability to achieve a designed curvature. Also in color cathode ray tubes.

The electron beam passing through the circular aperture 5 in the perforated area 4 must be accurately aligned with the position of the phosphor arranged on the inner surface of the panel, but there is distortion due to the compressive stress as described above. Sometimes, the position of the circular aperture 5 changes after several heating steps of 400 to 500 C in the plaque tube manufacturing process, and the electron beam passing through this aperture misses the exact position of the phosphor on the inner surface of the panel. , resulting in what is called a mislanding. A margin is provided in the design of the color cathode ray tube for this mislanding, but if the amount of mislanding exceeds this margin, problems such as color unevenness and color shift may occur, resulting in poor display quality. be.

Usually, the material for shadow mask is 0.1~0.3m.
A thin sheet of mild steel with a thickness of m is used, but since the coefficient of thermal expansion of mild steel is 25 to 100 C and is large, approximately 10 The shadow mask thermally expanded, causing mislanding due to so-called doming, resulting in color unevenness and deviation of one color during operation. Therefore, recently, a Ni--Fe amber type alloy, which has an extremely low coefficient of thermal expansion near room temperature, has been attracting attention as a new shadow mask material.

For example, the thermal expansion coefficient of 36% N1-F6 amber type alloy is about 2 x 10-#/l:' at 20 to 100C, which is about 175 that of mild steel. Therefore, Ni-Fe with
Mislanding caused by doming can be reduced by using an amber type alloy as a shadow mask material, but since the Ni-Fe amber type alloy is a harder material than mild steel, it is difficult to press during press forming. High compressive stress.

Press forming is not carried out sufficiently, and phenomena such as distortion are more pronounced than in the case of mild steel, which has the drawback of easily causing color unevenness, color shift, etc.

An object of the present invention is to provide a color shadow mask for a cathode ray tube that does not cause unevenness in one color or color shift, except for the defects that occur during press molding of a shadow mask for a cathode ray tube.

(Means for Solving the Problems) The present invention provides a curved surface portion consisting of a perforated region having a large number of circular apertures and a non-porous region without any apertures around the perforated region, and a curved surface portion around one curved surface portion. A shadow mask for a color cathode ray tube consisting of a skirt portion bent at a substantially right angle to the opposite side, characterized in that a groove or circular hole that does not penetrate is provided between the small diameter holes on the electron gun side of the perforated region. . The present invention is particularly effective when a hard Ni--Fe amber type alloy is used as the shadow mask material.

(Example) FIG. 1(a) is a front view of the effective area 4 of a shadow mask for a color cathode ray tube according to an embodiment of the present invention, viewed from the fluorescent surface side, and FIG. straight line m-m' of a)
FIG. As shown in Figure 5IE1, there is a large diameter hole 6 on the fluorescent surface side of the shadow mask 4, a small diameter hole 7 on the electron gun side, and a circular opening where the large diameter hole 6 and the small diameter hole 7 intersect. 5, and an SS is provided between adjacent small diameter holes on the electron gun side. In FIG. 1, the small-diameter hole 7 and the circular aperture 5 are distinguished, but there are cases where the small-diameter hole and the circular aperture coincide and it is impossible to distinguish between them.

The shadow mask for a color cathode ray tube according to the present invention is formed by press molding in the same manner as the conventional shadow mask for a color cathode ray tube.

When the groove 8 is provided between adjacent small diameter holes on the electron gun side, the compressive stress generated on the surface on the electron gun side during rounding and press molding can be made very small.

For this reason, press forming is carried out sufficiently, and the perforated area 4 does not bend or the like, and there is little distortion due to compressive stress, and even after the heat process in the plastic tube manufacturing process, the position of the circular hole in the perforated area 4 does not change as much as before. It has the advantage that it is much smaller than a shadow mask, and that mislanding can be greatly reduced, and color unevenness and color shift caused by this can be eliminated.

FIG. 2 is a view of another embodiment of the color cathode ray tube shadow mask according to the present invention, as seen from the fluorescent surface side of the perforated region 4. By providing a circular hole 9 that does not penetrate approximately in the middle of the small diameter hole 7, the compressive stress generated on the electron gun side surface during press molding can be made extremely small. Similarly, it has good press formability and eliminates color unevenness and color shift.

(Effects of the Invention) As detailed above, according to the present invention, a shadow mask is pressed by providing a groove or a circular hole that does not penetrate between the small diameter holes on the electron lower side of a shadow mask for a color grain tube. It reduces the compressive stress generated during forming by molding, prevents bending in the perforated area due to sufficient press molding, and reduces the positional fluctuation of the perforations after the heat process in the cathode ray tube manufacturing process. It is possible.

This has the effect of being able to eliminate color unevenness and color shift caused by this.

Of course, this effect can also be obtained with a thin sheet of mild steel that is normally used as a shadow mask material, but Ni-Fe
This effect is remarkable when using a material such as an amber type alloy, which is harder than mild steel and has a large compressive stress during press forming.

[Brief explanation of the drawing]

Figure 5IEI (al, (bl) is a front view and cross-sectional view of the effective area of a color cathode ray tube shadow mask according to one embodiment of the present invention, Figure 2 is a front view of another embodiment, and Figure 3 is a conventional color A perspective view of a shadow mask for a cathode ray tube, and FIGS. 4(a) and 4(b) are a front view and a cross-sectional view of an effective area of a conventional shadow mask for a color cathode ray tube. 1 Shadow mask, 2 ······curved surface,
3...Skirt portion, 4...Perforated area,
5...Circular hole, 6...Large diameter hole, 7.
...Small diameter hole, 8...Groove, 9...
circular hole. Mine 1 rhyme (G) 子 2 times

Claims (2)

[Claims] (1) A curved surface portion consisting of a perforated region having a large number of circular holes and a non-porous region without any perforations around the perforated region, and a skirt portion bent around the curved surface portion at approximately right angles to the curved surface portion. In a color cathode ray tube shadow mask consisting of
A shadow mask for a color cathode ray tube, characterized in that a non-penetrating groove or circular hole is provided between small-diameter holes on the electron gun side of a perforated region. (2) Claim No. 1 characterized in that a Ni-Fe amber type alloy is used as the shadow mask material.
) Shadow mask for color cathode ray tubes.