JPS581500B2 - shadow mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improvement that prevents deformation of the shadow mask, especially the effective surface.

As shown in FIGS. 1a and 1b, a conventional shadow mask 1 has a rectangular effective surface 2 and a large number of rectangular through holes 3.

This rectangular through hole 3 has a characteristic that it has a higher electron beam transmittance than a conventional round hole, so that a bright screen can be obtained.

However, on the other hand, since its mechanical strength is weak, a disadvantage arises in that a part of the effective surface 2 is deformed as shown in FIG.

This phenomenon particularly occurs only around the effective surface.

The reason for this is that the mechanical strength of the bridges 4 between the through holes 3 arranged in the longitudinal direction of the elongated through holes is extremely weak.

Therefore, this part becomes a bottleneck and deformation occurs.

Now, as shown in FIG. 3, the fluorescent surface combined with this shadow mask is a fluorescent surface 6 made up of striped phosphors 5R, 5G, and 5B formed continuously in the longitudinal direction of this shadow mask. It is formed.

Naturally, the fluorescent surface 6 is formed by the shadow mask 1 that is combined with the shadow mask 1.

Therefore, the following points must be considered.

That is, if the width of the bridge 4 is widened, when forming a phosphor surface, this bridge portion becomes a shadow during exposure as is well known, and as shown in FIG. 5R is partially constricted 7 and normal stripes cannot be formed.

This results in unfavorable results regarding the landing of the electron beam.

Therefore, it is preferable that the bridge 4 is unnecessary or made extremely narrow for purposes such as forming a fluorescent surface or improving electron beam transmittance to obtain a bright screen.

However, the effective surface of the shadow mask is curved with a predetermined curvature in order to match the panel surface on which the fluorescent surface is formed.

This is usually formed by pressing, during which bridging deformation, so-called elongation, occurs.

In particular, the peripheral surface of the effective surface, which requires mechanical strength, is more deformed than the central portion.

This is due to the difference in mechanical strength between the effective part with through holes and the ineffective part without through holes.

Although it is conceivable to make the mask thicker to increase its mechanical strength, the relative strength of the center and peripheral parts of the mask remains the same, and this does not prevent the above deformation.

From the above points, the present invention has the opposite relationship between, on the one hand, the need to widen the width of the bridge in order to maintain strength, and on the other hand, the need to narrow the width of the bridge 4 due to the formation of a fluorescent surface, etc. Therefore, the dimensions of the bridge 4 become extremely important.

The inventors of the present invention focused on this point and made repeated improvements, and as a result, they succeeded in achieving both strength and formation of a fluorescent surface.

In other words, the width of the bridge should be made as narrow as possible in the center of the effective surface so as to sufficiently contribute to the transmittance of the electron beam and the striped phosphor formed on the phosphor surface, and mechanical In order to provide sufficient mechanical strength, the width of the bridge is made wider than the central portion.

In other words, the bridge cross-sectional area at the periphery of the effective surface is made larger than that at the center, and the mechanical strength is made greater than at the center.

However, it is important that this width is wide enough to prevent the above-mentioned "constriction" from appearing in the stripes on the fluorescent surface, and the maximum width is set to 0.25 mm.

On the other hand, the bridge width at the center is set to a minimum of 0.05 mm to prevent deformation during pressing or after completion.

Furthermore, another method is to increase the number of bridges while maintaining the maximum width, thereby increasing the density of bridge formation around the effective surface and substantially increasing the mechanical strength. .

If the bridge has an acceptable amount of elongation over the entire effective surface during mask molding, has sufficient mechanical strength, and has good screen brightness and fluorescent surface unevenness, the size of the through hole can be adjusted. The hole pitch in the direction perpendicular to the stripe may be the same as the conventional one.

In other words, in this application, the bridge width is changed in order to relatively change the strength of the central part and the peripheral part of the mask effective surface (strengthen the peripheral part), and here the size of the through hole and the direction perpendicular to the stripe are changed. The hole pitch is not an important parameter for the mechanical strength in the bridge direction.

Next, an embodiment of the present invention will be described with reference to FIG.

Shadow mask 1 made of a soft iron plate with a thickness of about 0.18 mm
In the periphery 12 of the effective surface 11 of 0, the width W of each bridge 14 arranged between the rectangular electron beam transmission holes 13 in the longitudinal direction (Y-axis direction) is approximately 0.25 mm. W1 as you approach the Y axis at the center of the plane
is about 0. 18 mm, W2 is approximately 0.15 mm, and W3 is approximately 0.07 mm, and the sizes of the electron beam transmission holes 13 are all constant.

Therefore, the pitch P of the through hole is different between the periphery and the center.

The periphery of the shadow yask 10 formed in this way can widen the width of the bridge 14 and increase its mechanical strength, preventing deformation of this area and allowing the striped phosphor to fluoresce without constriction. This made it possible to form a surface.

FIG. 6 shows another embodiment of the present invention, in which the pitch P of the electron beam transmission hole 13 in the peripheral part of the effective surface 11 and the pitch P of the transmission hole 13 in the central part are constant. However, the length of the through hole 13 is made shorter in the peripheral part than that in the central part, so that the width of the bridge is wide at the periphery and narrow at the W center.

The present invention, configured as described above, can prevent deformation of the effective surface of the shadow mask 10 due to a decrease in mechanical strength at the periphery, and can also reduce the amount of electron beam transmission at the periphery. We were able to minimize the dark areas around the effective screen on the fluorescent surface.

Furthermore, there is an effect that a good striped fluorescent surface can be formed with almost no influence on the shape of the striped fluorescent light.

As described above, in the present invention, the deformation of the effective surface that occurs when the shadow mask is curved is prevented, and when this shadow mask is installed in the picture tube and faces the fluorescent surface, the entire effective surface is Since the shadow mask is maintained at a constant distance (approximately 10%) from the tube panel surface over the entire period, the relative relationship between the through hole of the shadow mask and the phosphor is maintained accurately, so it is not affected by temperature changes during operation. It also has various improvement effects, such as almost eliminating color shift phenomena such as smearlanding.

If the width W of the bridge 14 is set to 0.25 mm or more, the shape of the striped phosphor coating will be deformed as shown in FIG. 4, resulting in uneven luminance, which is not preferable.

Therefore, the width W of the bridge 14 at the periphery is approximately 0.
．． A value of about 25% to 0.18% is good, and a value of about 0.12 to 0.05% in the central part is sufficient to satisfy both mechanical strength, formation of striped phosphors, and prevention of reduction in luminance. I understand.

[Brief explanation of drawings]

FIG. 1a is a perspective view of a conventional shadow mask, FIG. 1b is an enlarged perspective view of a part thereof, and FIG. 2 is a sectional view showing a part of the shadow mask in FIG. 1 in a deformed state. FIG. 4 is a sectional view and a sectional perspective view for explaining the relationship between a shadow mask and a fluorescent surface for explaining the present invention, and FIGS. 5 and 6 are front views of a part of the shadow mask of the present invention. It is. 10...Shadow mask, 11...Effective surface, 12...Peripheral area, 13...Transmission hole, 14...Bridge.

Claims (1)

[Scope of Claims] 1. A through hole having an elongated shape, the length of the through hole in the longitudinal direction being constant over the effective surface, and the pitch of the peripheral part being larger than the pitch of the central part, and the through hole in the longitudinal direction. The maximum interval between is 0.
2 5 mm, and a minimum interval of 0.05 mm. 2. It has elongated through holes, and the pitch of the through holes is constant over the entire effective surface, and the distance between the through holes in the longitudinal direction is changed sequentially so that it is narrower at the center of the effective surface and wider at the periphery. The maximum interval between them is 0.25mm, the minimum interval is 0.05m
A shadow mask characterized by m.