JPH04147541A - Color image receiving tube - Google Patents

Abstract

PURPOSE:To change equivalent plate thickness of shadow mask, and enable the change of deformation strength by performing half etching to a holeless area arranged in the periphery of a holed area so that etching quantity per unit area is different partially. CONSTITUTION:A shadow mask open hole made of a slot or a dot, which transmits electron beams, is drilled in a holed area 1, and half etching is performed to a holeless area 2 so that etching quantity per unit area is different. In this case, when a pitch of the half etching is made fine and a hole diameter is enlarged, etching quantity per unit area can be changed remarkably. Consequently, a pitch of the half etching part near a part to be deformed easily is made small, and a hole diameter is enlarged to reduce a difference of deformation strength between an open hole part and the half etching part to reduce deformation of the open hole to the degree without practical problem.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to color picture tubes, and particularly to shadow mask type color picture tubes.

[Conventional technology]

In the shadow mask type color picture tube, since the shadow mask, which is a color selection electrode, has a transmittance of only 15 to 20%, thermal expansion occurs due to the impact of the electron beam emitted from the electron gun. Therefore, the position of the shadow mask changes,
The electron beam that passes through the shadow mask apertures consisting of slots or dots no longer lands on a predetermined phosphor, resulting in deterioration of color purity. This phenomenon becomes noticeable when a large amount of anode current is applied or in color picture tubes with flat screens.

Therefore, a low thermal expansion material such as an invar material (36% Ni-Fe alloy) is used as a shadow mask material to suppress deterioration of color purity due to thermal expansion of the shadow mask.

The shadow mask has a predetermined curved shape through press molding, but the amber material has higher yield strength and less elongation than pure iron material. Therefore, during press molding, the perforated region of the shadow mask, which is more easily deformed than the non-porous region of the shadow mask, is stretched, and the shape of the aperture of the shadow mask in the peripheral portion is deformed. In order to prevent this shadow mask hole deformation, half-etching is uniformly applied to either the front or back surface of the non-porous area of the shadow mask.

[Problem to be solved by the invention]

Press molding of a shadow mask involves applying pressure with a press mold to form a predetermined curved surface while the non-porous area of the shadow mask plate is stretched, and then squeezing the non-porous area to form a curved surface.

During the drawing process during curved surface forming, the holes are significantly deformed at the side edges of the shadow mask perforated area where strong stress is applied, resulting in problems such as the holes becoming elliptical or connecting with adjacent shadow mask holes. Irritation occurs.

In order to prevent this, conventional shadow mask plates have uniform half-etching applied to the front or back surface to weaken the mechanical strength in non-porous areas.

However, in the above-mentioned drawing process, an even tensile stress is not normally applied to the half-etched non-porous region, so in the conventional half-etching pattern, the amount of elongation is too large or too small for the tensile stress.

Therefore, there are differences in the way the shadow mask stretches and the deformation of the apertures depending on the location, and there is a drawback that a predetermined shadow mask curved surface shape and effective screen shape cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color picture tube having a shadow mask with a uniform elongation and aperture deformation and a predetermined curved surface shape or effective screen shape.

[Means to solve the problem]

The present invention includes a perforated region in which an electron beam transmission hole is formed;
In a color picture tube equipped with a shadow mask having a non-porous area disposed on the outer periphery of the perforated area, half-etching is performed on the non-porous area so that the amount of etching per unit area is partially different. has been done.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a shadow mask according to an embodiment of the present invention;
FIG. 2 is a characteristic diagram showing the relationship between the pitch of half etching in the non-porous region of FIG. 1 and the ratio of the amount of etching per unit area.

As shown in FIG. 1, a shadow mask aperture consisting of a slot or dot that transmits the electron beam is perforated in the perforated region 1, and half holes are formed in the non-perforated region so that the amount of etching per unit area is different. Etched.

As shown in FIG. 2, when the hole diameter is constant, the hole pitch and the amount of etching per unit area are in a quadratic function relationship. For example, change the pitch from 0.40w+m to 0.36i+
When the etching is made finer by 10% to m, the amount of etching per unit area increases by about 23%. Therefore, the equivalent plate thickness of the shadow mask decreases, and the deformation strength at that point decreases.
It becomes easier to deform.

FIG. 3 is a characteristic diagram showing the relationship between the etching pore diameter and the etching amount ratio per unit area in the non-porous area shown in FIG.

As shown in FIG. 3, when the pitch is constant, the hole diameter and the amount of etching per unit area are approximately proportional. For example, change the hole diameter from 0.14n+ to 0.154mm by 10
%, the etching amount per unit area is approximately 2
1% more.

The above example shows the relationship between the change in the amount of etching when the pitch and hole diameter are changed individually, but if the pitch of half etching is made finer and the hole diameter is made larger, the amount of etching per unit can be greatly increased. It can be changed.

FIGS. 4(a) and 4(b) are characteristic diagrams illustrating changes in the amount of etching per unit area of half etching in a non-porous region.

To change the amount of etching per unit area,
As shown in Figure 4(a), the amount of etching on the diagonal axis is increased by 20% compared to the horizontal and vertical axes, and the angle between each axis is a combination of quadratic trigonometric functions with respect to the angle θ formed with the horizontal axis. By changing the diameter, it was possible to reduce the deformation of the opening at the corner of the diagonal axis.

As another example, as shown in FIG. 4(b), half-etching in the non-porous area is expressed as a function of the distance r from the boundary between the perforated area and the non-porous area in the radial direction. By increasing the amount of etching in the effective area and non-porous area by 20% compared to the amount of etching at the edge, deformation of the openings near the effective area could be reduced.

In this way, in conventional half-etched shadow masks with uniform pitch and uniform openings, even if the shape of the openings is deformed by pressing, the pitch of the half-etched parts in the vicinity where deformation is likely to be reduced is reduced, and the hole diameter is increased. By partially reducing the difference in deformation strength between the aperture and the half-etched part, the deformation of the aperture could be reduced to a level that poses no practical problem.

〔Effect of the invention〕

As explained above, the present invention changes the pitch and diameter of the holes during half-etching in the non-porous area of the shadow mask, thereby changing the equivalent plate thickness of the half-etching shadow mask and increasing the deformation strength at that location. It can be changed. Therefore, by lowering the deformation strength caused by half etching near the places where stress is concentrated during press molding of the shadow mask, the half etching region can be easily stretched, and the deformation of the holes in the perforated region of the shadow mask can be suppressed. It has the effect of

It also has the effect of suppressing deformation of the effective screen shape due to uneven stretching of the perforated region during press molding.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a shadow mask according to an embodiment of the present invention;
Figure 2 is a characteristic diagram showing the relationship between the pitch of half etching in the non-porous area of Figure 1 and the etching amount per unit area, and Figure 3 is a characteristic diagram showing the relationship between the etching pore diameter and the etching amount per unit area in the non-porous area of Figure 1. FIG. 4 (a>, (b) is a characteristic diagram illustrating the change in half etching per unit area in a non-porous region. 1... Porous region , 2... non-porous area.

Claims (1)

[Scope of Claims] 1. In a color picture tube equipped with a shadow mask having a perforated region in which an electron beam transmission hole is formed and a non-porous region disposed on the outer periphery of the perforated region, A color picture tube characterized in that a hole region is half-etched so that the amount of etching per unit area is partially different. 2. The color picture tube according to claim 1, wherein the non-porous region is formed by changing the pitch of half etching. 3. The color picture tube according to claim 1, wherein the non-porous region is formed by changing the size of a half-etched hole.