JPH064523Y2 - Shadow mask for color cathode ray tube - Google Patents

Description

The present invention relates to a shadow mask for a color cathode ray tube, and more particularly to a shadow mask used as an exposure mask.

(Prior Art) In a color cathode-ray tube equipped with an in-line type electron gun, the fluorescent bodies forming the fluorescent surface must be formed in a stripe shape due to the structural characteristics of the electron gun. Black metrics are formed between the fluorescent stripes by a light-absorbing substance such as graphite in order to prevent a decrease in brightness due to external light.

The fluorescent stripes and the black metrics are formed by using a photosensitive synthetic resin through a photo-etching method, that is, exposure and development. Here, as the exposure mask, a shadow mask for guiding an electron beam from a completed color cathode ray tube is usually used. One example of such a conventional shadow mask is shown in FIG. In FIG. 1, a shadow mask 1'is made of a thin metal plate on which a number of slit-shaped apertures 2 each having a width h are formed.

On the other hand, an example of an exposure apparatus is shown in FIG. 2 in order to explain a method of exposing the panel surface using such a shadow mask 1'as an exposure mask. In this exposure apparatus, a shadow mask 1'is mounted as an exposure mask on the inside of a panel 5 whose inner surface is coated with a photosensitive substance, and a panel is provided with a shutter 7 which forms a slit 7a for light emitted from a light source 6. 5 by moving in the direction of the short side of 5 to continuously expose the inner surface of the panel 5 stepwise,
Alternatively, the stripes of the fluorescent material are formed.

However, since the distance from the light source 6 to each part on the inner surface of the panel 5 is different and the illuminance of each part is different, the degree of exposure is different. Therefore, the formation state of the black metrics or the fluorescent stripes formed on the inner surface of the panel 5 becomes defective. For example, in the case of black metrics that is usually formed before the fluorescent stripes, the exposed portion is peeled off. Therefore, when the exposure is insufficient, the width of black metrics (B) is defined as shown in FIG. 3A. The width becomes irregularly larger than the width, and when the amount of exposure is excessive, it becomes the opposite as shown in FIG. 3B, and the linearity of the black metrics (B) becomes extremely poor. When the linearity of the black metrics (B) is poor, the formation state of the fluorescent stripes formed between them is also very poor.

Conventional attempts to solve such problems include, for example,
As disclosed in Japanese Utility Model Publication No. 58-41633, the method was mainly to change the slit shape of the shutter.

(Problems to be solved by the invention) However, this method has not been an appropriate solution to the above-mentioned problems.

In view of the above conventional problems, an object of the present invention is to provide a shadow mask for a color cathode ray tube, which can be used for an exposure mask to make the exposure amount on the entire panel uniform.

(Means for Solving the Problems) The present invention relates to a shadow mask for a color cathode ray tube having a large number of apertures for respectively guiding electron beams, wherein at least one of a pin cushion type aperture and a drum type aperture is provided in the shadow mask. 1 and the slit-shaped aperture are mixed and formed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4A shows the shape of an aperture formed in the shadow mask according to the present invention, which is a pin-cushion type (Pin-cu
FIG. 4B shows a shape of an aperture formed in a shadow mask according to the present invention, which is a drum type aperture. The pin cushion type aperture 3 has a minimum width (h1) and a maximum width (h2),
The drum aperture 4 has a minimum width (h3) and a maximum width (h
4) and. Pincushion type aperture 3 here
Maximum width (h2) of the drum-shaped aperture 4 and minimum width (h2) of the drum-shaped aperture 4
It is preferable that the widths (3) of the slit-shaped apertures 2 are substantially the same as the widths (h) of the slit-shaped apertures 2. Therefore, the opening area of the pin cushion type aperture 3 becomes smaller than the opening area of the slit type aperture 2, and the opening area of the drum type aperture 4 becomes larger than the opening area of the slit type aperture 2.

Here, the minimum width of the pincushion type aperture 3 (h
1) and the maximum width (h4) of the drum-shaped aperture 4 are almost the same as the width (h) of the slit-shaped aperture 2, the opening area is opposite to that in the above-mentioned embodiment. In this way, when it is used in combination with the slit-shaped aperture 2, it is difficult to align it in-line, which is not preferable.

The various apertures according to the present invention are shown in FIG. 5A,
As shown in FIG. 5B, the shadow mask 1 is mixed and formed. For example, if the exposure amount near the outer center of the long side is over the standard value and the exposure amount near the outer center of the short side is less than the standard value, the outer center of the long side where the exposure amount is excessive. A pincushion type aperture 3 is formed in the vicinity, and a drum type aperture 4 is formed in the vicinity of the outer center of the short side portion where the exposure amount is insufficient. (The reverse case is as shown in FIG. 5B.) Here, the maximum width (h2) of the pincushion type aperture 3
Is formed to be almost the same as the width of the slit aperture 2 as described above, and its minimum width (h1) is gradually increased in accordance with the excessive amount of the exposure amount. It is preferable to form so as to be close to the two forms. Also, it is preferable that the drum-shaped aperture 4 is formed by gradually decreasing the maximum width (h4) similarly to this.

The operation of the shadow mask according to the present invention will be described below.

The shadow mask constructed according to the present invention is installed,
It is used as an exposure mask for exposing the inner surface. In the following, for convenience of description, the process of forming black metrics will be described, but the same applies to the formation of fluorescent stripes.

When the light is emitted from the light source 6, this luminous flux causes the slit 7a of the moving shutter 7 to expose the inner surface of the panel 5 stepwise. This is for each aperture 2, 3,
4 has the same effect as moving it in its longitudinal direction relative to the inner surface of the panel.

(Effect of the Invention) Therefore, since the exposure amount for each stripe forming position on the inner surface of the panel 5 is controlled, in the case of the pincushion type aperture 3, the opening cross-sectional area thereof is the opening of the slit type aperture 2 generally. Since the average cross-sectional area is smaller than the partial cross-sectional area, the average light passing amount is reduced, and the opposite is true in the drum-shaped aperture 4, and as a result, the intensity of light reaching each part of the inner surface of the panel 5 is almost uniform. As a result, the overall exposure amount of the panel becomes uniform.

As a result, in the entire panel, the photosensitive deviation at the exposed portion is reduced, and the black metric formation state, particularly the linearity and density, becomes extremely uniform.

In addition, since the use of the shadow mask according to the present invention makes it possible to form a high-quality fluorescent film, there is an advantage that a high-quality color cathode ray tube that provides an excellent image can be produced.

[Brief description of drawings]

FIG. 1 is a partially enlarged perspective view showing the structure of a conventional shadow mask frame, FIG. 2 is a schematic sectional view showing an ordinary exposure apparatus, and FIG. 3A is an enlarged plan view of an inner surface of a panel showing defective formation of black metrics. It is a figure, underexposure state, 3rd
FIG. 6B is an enlarged plan view of the inner surface of the panel showing defective formation of black metrics, and is a diagram relating to an excessive exposure state. FIG. 4A is a schematic view showing a form of an aperture formed in a shadow mask according to the present invention, and FIG. 4B shows a form of an aperture formed in a shadow mask according to the present invention. It is a schematic diagram, and is a figure about a drum type. 5A and 5B are plan views showing an embodiment of the shadow mask constructed according to the present invention. 1 ... Shadow mask, 2 ... Slit aperture, 3 ...
Pincushion type aperture, 4 ... Drum type aperture, 5 ... Panel, 6 ... Light source, 7 ... Shutter, 7a ... Slit.

Claims (5)

[Scope of utility model registration request] 1. A shadow mask for a color cathode ray tube having a plurality of apertures for respectively guiding an electron beam, wherein the shadow mask has at least one of a pin cushion type aperture and a drum type aperture and a slit type aperture. A shadow mask for a color cathode ray tube, characterized in that the shadow mask is formed by mixing. 2. The pincushion-shaped aperture, wherein the shadow mask is used as an exposure mask,
The shadow mask for a color cathode ray tube according to claim 1, wherein the shadow mask is formed in a portion where dimming is required. 3. The shadow mask for a color cathode ray tube according to claim 1, wherein the drum-shaped aperture is formed in a portion where brightening is required when the shadow mask is used as an exposure mask. 4. The shadow for a color cathode ray tube according to claim 1, wherein the maximum width of the pincushion type aperture is almost the same as the width of the slit type aperture. mask. 5. The shadow mask for a color cathode ray tube according to claim 1, wherein the minimum width of the drum-shaped aperture is almost the same as the width of the slit-shaped aperture.