JPS59141151A - Shadow mask-type color crt - Google Patents

Abstract

PURPOSE:To improve the mechanical strength and increase the number of holes by tilting the plane containing the minimum diameter sections of holes in relation to the front and rear surfaces of a shadow mask bored with many holes. CONSTITUTION:A shadow mask 5 formed with many holes 50 is arranged opposite to a phosphor screen formed inside a panel 1 of a CRT. A plane containing the minimum diameter sections 53 of holes 50 is formed between the front surface and rear surface of the mask 5, and the plane containing the diameter sections 53 is crossed with the center of the diameter section at a point F on the front surface of the mask 5 in the center of the mask 5 and is crossed at a point G on the rear surface of the mask 5 in the periphery of the mask 5. An electron beam 41 is projected nearly at a right angle to the plane containing the diameter sections 53. The degree of tilt of the plane containing the diameter sections 53 is made gradually larger at the periphery than at the center and is made symmetrical in relation to the center. Accordingly, even when many holes 50 are formed, the distance between holes can be increased and the mechanical strength while molding the mask 5 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shadow mask type color cathode M tube, and in particular to an improvement in the shape of the hole in the shadow mask.

Generally, a color cathode ray tube has a configuration as shown in FIG. In the figure, (1) is a panel that is a dish-shaped container, (2) is a funnel-shaped container, and the panel (1) and funnel (2) are made of frit glass (3) that is a welded glass. After welding, an electron gun (4) is enclosed to keep the inside of the tube in a vacuum state. A fluorescent screen (not shown) is formed on the inner surface of the panel (1), and a shadow mask (5), which is a color selection mechanism, is arranged opposite to this fluorescent screen. The shadow mask (5) is held in a predetermined position by a holding mechanism (7) that is engaged with a bottle (6) embedded and fixed in the panel (1). The approximate shape of this shadow mask (5) is a spherical shape similar to the inner surface shape of the panel (1), and this shadow mask (5) has a large number of holes. (7
) is formed into a round hole as shown in Fig. 2, and consists of a large diameter hole (51J) and a small diameter hole (support).In other words, it is formed on the front side (panel side) of the shadow mask (5). There is a large diameter hole (51) on the side, and a small diameter hole (51) on the back side (electron gun side).
branches) are formed respectively. And the electron gun (4)
The electron beam emitted from the phosphor screen has a size determined by the small diameter hole (support) and impinges on the phosphor screen, causing the phosphor screen to emit light.

FIG. 3 shows a cross section of the hole (2). As is clear from the figure, the minimum diameter part A-A (5
20) is the surface 0- of the shadow mask (5)
C and the back surface B--B.

As mentioned above, the shadow mask (5) is formed into a roughly spherical shape, so in reality, as shown in FIG. However, the trajectory of the electron beam tends to be inclined from the plane including the minimum diameter part (520) as it approaches the peripheral part of the shadow mask (5). . This is due to the fact that the center of curvature of the shadow mask (5) and the center of deflection of the electron beam are different.

By the way, one way to improve the image quality of a color cathode ray tube is to increase the number of picture elements that make up the screen. For this purpose, it is necessary to form many holes in the shadow mask (5), but in the conventional shadow mask (5) described above, as the number of holes increases, the distance between the holes becomes shorter.
As a result, there was a drawback that the mechanical strength during molding of the shadow mask (5) was reduced.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a color cathode ray tube having a shadow mask with improved mechanical strength.

Embodiments of the present invention will be described below based on the drawings.

FIG. 5 shows a cross section of a hole in the periphery of a shadow mask in an embodiment of the present invention.

Here, a feature is that the plane including the minimum diameter part between the holes is inclined with respect to the front and back surfaces of the shadow mask (5). That is, when the minimum diameter portion is formed between the front and back surfaces of the shadow mask (5), this minimum diameter portion (53
) intersects with the center of the minimum diameter part at point F on the surface of the shadow mask (5) on the center side of the shadow mask (5), and on the peripheral side of the shadow mask (5), the plane including the shadow mask ( 5) intersect at the 0 point on the back side.

Next, with reference to FIG. 6, a description will be given of the difference from the conventional method in the case of forming the holes (2) as described above. In Figure 6,
The hole shape shown by the solid line is the case of the present invention, and the hole shape shown by the broken line is the case of the conventional case. As is clear from this, in the case of the present invention, compared to the cross section 621) in the conventional case shown by the cross line, the cross section is substantially increased by the shaded portion 31). Therefore, no matter how many holes are formed, the distance between the holes will be larger than before.
The mechanical strength during molding of the shadow mask (5) can be improved. In addition, as shown in FIG. 6, by making the plane including the minimum diameter part (53) perpendicular to the trajectory of the electron beam (411), the inner diameter at the minimum diameter part becomes the smallest, and the shadow mask (53) ) has the maximum mechanical strength.

FIG. 7 shows the screen of a color cathode A-tube, with the horizontal and vertical axes orthogonal to each other at the center 0 of the screen being the X and Y axes, respectively.

FIG. 8 is a schematic diagram showing the degree of inclination of the plane including the minimum diameter portion (53) formed in the present invention with respect to the X-axis. As will be seen, the degree of inclination increases from the center of the screen O, in other words, from the center of the shadow mask (5) to the periphery. This trend is also true for the Y-axis and °C. The degree of inclination is symmetrical with respect to the center of the shadow mask (5).

The reason that the degree of inclination becomes larger toward the periphery is due to the traveling direction of the electron beam, as described above.

In addition, in the above embodiment, the holes were formed as round holes, but
It goes without saying that the holes may be formed in the form of stripes of elongated holes.

As described above, according to the present invention, the plane including the minimum diameter part of the hole is inclined with respect to the front and back surfaces of the shadow mask, so the number of holes in the shadow mask can be increased in order to improve image quality. However, the distance between the holes can be larger than before, and as a result, the shadow mask will not be damaged during press molding, and its mechanical strength will be improved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the configuration of a color cathode ray tube, Figure 2 is a partially enlarged plan view of a conventional shadow mask, Figure 6 is a sectional view of the same, and Figure 4 shows the relationship between the holes in the shadow mask and the electron beam. FIG. 5 is a cross-sectional view showing an example of the hole shape of the shadow mask in the color cathode a't of the present invention, and FIG. 7 is a front view showing the screen of a color cathode ray tube, and FIG. 8 is a schematic diagram showing the degree of inclination of the plane including the minimum diameter portion. (5)...shadow mask, (7)...hole, (g)
...Minimum diameter part. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) In a color cathode ray tube having a shadow mask with a large number of holes, a shadow mask type characterized in that a plane including the minimum diameter portion of the holes is inclined with respect to the front and back surfaces of the shadow mask. Color cathode ray tube. (2) A shadow mask type color cathode ray tube according to claim 1, wherein the plane is substantially perpendicular to the trajectory of the electron beam. (3) The degree of inclination of the plane increases from the center of the shadow mask toward the periphery, and the degree of inclination is symmetrical with respect to the center of the shadow mask. Shadow mask type color cathode ray tube (4) The minimum diameter section is formed between the front and back surfaces of the shadow mask, and the plane including this minimum diameter section is oriented toward the center of the minimum diameter section of the shadow mask. 2. The shadow mask type color cathode ray tube according to claim 1, wherein the center side of the shadow mask intersects with the front surface of the shadow mask, and the peripheral side of the shadow mask intersects with the back surface of the shadow mask.