JP2944114B2 - Material plate for shadow mask - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to a material plate for a shadow mask of a shadow mask type color cathode ray tube.

(Prior Art) Generally, as shown in FIG. 3, a shadow mask type color CRT is a three-color phosphor layer formed on the inner surface of a panel (2) of an envelope (1) and emitting blue, green and red light. A shadow mask (4) in which a large number of electron beam passage holes are formed in a predetermined arrangement is disposed inside and opposed to the fluorescent screen (3) made of. On the other hand, an electron gun (8) for emitting three electron beams (7B), (7G), and (7R) is arranged in a neck (6) of a funnel (5) integrated with the panel (2). The three electron beams (7B), (7G), and (7R) emitted from the electron gun (8) are deflected by a magnetic field of a deflection yoke (not shown) mounted outside the funnel (5). The phosphor screen (3) is horizontally and vertically scanned through a shadow mask (4) to form a color image.

The electron beam passage hole of the shadow mask (4) functions as a color selection electrode for selecting the three electron beams (7B), (7G), and (7R) and properly landing them on the corresponding three-color phosphor layers. It has something.

In order to display an image with good color purity on the phosphor screen (3), as shown in FIG. 4, the electron beam passage hole (9) of the shadow mask (4) is provided with the electron beam passing hole (9). For the electron beams (7B), (7G), and (7R), it is important to reduce the number of electron beams that collide with the side wall of the electron beam passage hole (9) and reflect toward the phosphor screen. The opening diameter Ds on the surface side is larger than the opening diameter De on the electron gun side,
Further, it is formed in a shape having a minimum diameter portion (10) at a position near the opening on the electron gun side.

Conventionally, such a shadow mask is formed by opening an electron beam passage hole (9) by a photo-etching method using a strip-shaped metal thin plate such as an aluminum killed low carbon steel plate as a material plate for the shadow mask, and then cutting into a predetermined shape. And formed by molding.

In manufacturing a shadow mask by the photoetching method, first, a strip-shaped material plate for a shadow mask having a predetermined width and length is washed, a photosensitive agent is applied to both surfaces thereof, and dried to form a photosensitive film. Next, a pair of negative masters in which a negative pattern of electron beam passage holes is formed on a glass substrate are exposed in close contact with the photosensitive films (12) on both surfaces, and the negative master patterns are printed on the respective photosensitive films. Thereafter, development is performed by spraying hot water to remove unexposed portions, and further, drainage is performed with a surfactant or the like, and a pattern corresponding to the pattern of the negative master is formed on both sides of the strip-shaped shadow mask material plate. A resist film is formed. After the resist film is dried, burning for curing the resist film is performed. Then, a predetermined electron beam passage hole is formed by spraying an etching solution, and then the resist film is peeled off with a caustic alkali solution.

FIG. 5 shows a vacuum adhesion baking apparatus for closely bonding and baking a negative master to photosensitive films formed on both surfaces of a shadow mask material plate in the production of the shadow mask. The vacuum contact baking apparatus includes a pair of frames (11a) and (11b) opposing each other so as to freely contact and separate from each other and a pair of the frames (11a) and (1a).
1b) A pair of negative masters (12a) and (12b) placed between them
And a vacuum line (14) for supporting the negative originals by sucking and holding the respective negative originals (12a) and (12b) through vacuum packings (13a) and (13b), and a negative with the frames (11a) and (11b). And a vacuum line for contact (15) for vacuum suctioning a space formed by the original plates (12a) and (12b).

The close contact printing of the negative master onto the photosensitive film formed on the surface of the material plate for the shadow mask is performed by a pair of frames (11
a), (11b) A pair of negative masters (12
Between a) and (12b), a material plate for a shadow mask (17) having a photosensitive film (16) formed on both surfaces is inserted, and the photosensitive film (16) is formed on both surfaces by suction of a vacuum line (15) for adhesion. ), A pair of negative original plates (12a) and (12b) are brought into close contact with each other, and the light is irradiated from a light source (not shown).

By the way, a negative master (12
In the contact baking of a) and (12b), if the adhesion failure occurs between the photosensitive film (16) and the negative masters (12a) and (12b),
Negative masters (12a) and (12b) to be printed on photosensitive film (16)
Of the pattern, the faithful transfer of the negative pattern cannot be performed, and the diameter of the formed electron beam passage hole changes to appear uneven, thereby deteriorating the quality of the shadow mask.

A major cause of the above-mentioned poor adhesion is that the vacuum line for contact (15) is arranged outside the pair of negative masters (12a) and (12b), and the negative master (12) is placed against the photosensitive film (16).
This is because the peripheral parts of a) and (12b) adhere closer to each other than the central part, and the passage for suctioning the central part is closed.
In particular, poor adhesion frequently occurs at the center.

As a means for preventing this poor adhesion, there is a method of roughening the surface of the material plate for the shadow mask. However, in order to make the surface rough until the state of adhesion is improved, the surface roughness Ra needs to be about 1.0 μm. However, if the surface is roughened to this extent, the shape of the electron beam passage hole will be deteriorated.

Therefore, conventionally, the surface roughness Ra of the material plate for the shadow mask can only be roughened to about 0.2 to 0.5 μm,
As a result, the adhesion of the negative master is poor, the time required for adhesion is long, and the negative pattern is not faithfully transferred due to poor adhesion, the change in the electron beam passage hole diameter appears uneven, and the quality is good. There is a problem that it is difficult to obtain a shadow mask.

(Problems to be Solved by the Invention) As described above, the shadow mask of the color cathode ray tube uses a strip-shaped metal thin plate as a material plate for the shadow mask.
A photosensitive film is formed on the surface, the negative master is closely exposed to the photosensitive film, the pattern of the negative master is baked, developed, and then etched by a photo-etching method. , The negative pattern is not faithfully transferred, and the diameter of the electron beam passage hole becomes uneven.

As a means for preventing poor adhesion between the photosensitive film and the negative master, there is a method of roughening the surface of the material plate for the shadow mask. To make the surface rough until the adhesion state is improved, the surface roughness Ra is about 1.0 μm. Need to be However, if the roughness is so large, the shape of the electron beam passage hole is deteriorated.
It can only be roughened to about 2 to 0.5 μm. As a result, the negative master has poor adhesion, it takes a long time to adhere, and the negative pattern is not faithfully transferred due to poor adhesion. There is a problem that it is difficult to manufacture a good quality shadow mask because the passage holes appear unevenly.

The present invention has been made in order to solve the above problems, and can improve the close contact of the photosensitive film with the negative original, improve the productivity of the shadow mask by shortening the time required for close contact, It is another object of the present invention to provide a shadow mask material plate capable of manufacturing a shadow mask that does not cause unevenness in the electron beam passage hole diameter by faithfully transferring a negative pattern without causing poor adhesion.

[Structure of the Invention] (Means for Solving the Problems) Electrons are formed by a photo-etching method comprising a plate material having a predetermined width and length, and exposing a photosensitive resin film formed on the surface of the plate material in close contact with a negative pattern. In the material plate for the shadow mask in which the beam passage hole is formed, the surface roughness of the end in the width direction of the plate was made larger than the surface roughness of the center in the width direction. Preferably, the surface roughness of the plate is changed continuously from the center in the width direction to the end in the width direction.

(Operation) As described above, the surface roughness of the width direction end of the shadow mask material plate is made larger than the surface roughness of the width direction center portion, and preferably from the width direction center to the width direction end. When continuously changing, when the negative master is brought into close contact with the photosensitive film on the surface of the shadow mask material plate by vacuum adhesion, the photosensitive film and the negative master are brought into close contact from their central part, and the adhesion is directed to the peripheral part. And can proceed
The negative master can be completely adhered to the photosensitive film in a short time.

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

FIG. 1 is a sectional view showing a surface state of a material plate for a shadow mask which is one embodiment of the present invention. This material plate for shadow mask (20) is made of strip-shaped metal thin plate such as aluminum-killed low carbon steel plate of thickness 0.10 ~ 0.20mm and width of 600mm. Are also roughened so that both ends in the width direction are rougher.

The surface roughness is shown by a solid line (22) in FIG. 2 where the horizontal axis is the distance from the center in the width direction and the vertical axis is the roughness. The broken line (23) indicates the surface roughness of the conventional shadow mask material plate shown for comparison. The surface roughness of the material plate for the shadow mask shown by the solid line (22) continuously and gradually changes from the center in the width direction to both end portions in the width direction. It is about 0.3 μm, almost the same as the surface roughness of the mask material plate, but the surface roughness of both ends in the width direction is almost the same as that of the conventional shadow mask material plate at the center. On the other hand, it is as coarse as about 0.5 μm.

When the surface of the shadow mask material plate is roughened so that both ends in the width direction are rougher than the center portion in the width direction, photosensitive films are formed on both surfaces of the shadow mask material plate, as shown in FIG. When the negative pattern of the negative master is printed on the photosensitive film by the vacuum contact printing apparatus shown in (1), the entire surface of the negative master can be brought into close contact with the photosensitive film in a short time. That is, if the surface roughness of the shadow mask material plate (20) is made rougher at both ends in the width direction than at the center in the width direction, even if suction is performed by a vacuum line for adhesion arranged outside the negative master, Adhesion starts from the central part where the surface roughness is dense, and the adhesion gradually spreads to the peripheral part, reaching an ultimate vacuum of 10 ^-6
Both can be brought into a completely close contact state by a suction time of about 100 seconds by a vacuum line for contact of mmHg.

Therefore, when the shadow mask is manufactured using the material plate for a shadow mask (20), the adhesion time can be shortened as compared with the related art, and the productivity of the shadow mask can be improved. A shadow mask with good quality can be manufactured without causing unevenness in the diameter of the passage hole.

In the above embodiment, the surface roughness of the material plate for the shadow mask was about 0.3 μm at the center in the width direction, and was about
Although the thickness is set to 0.5 μm, the same effect can be obtained even when the width is set to about 0.2 μm at the center in the width direction and about 0.7 μm at both ends in the width direction. However, if the surface roughness is more than 0.2 μm, the adhesiveness of the negative master decreases, and if the surface roughness is more than 0.8 μm, the hole shape of the electron beam passage hole deteriorates. It is preferable that the width is coarser at both ends in the width direction than at the center in the width direction, and that it is about 0.2 μm or more at the center in the width direction and about 0.7 μm or less at both sides.

[Effect of the Invention] The surface roughness of the width direction end of the shadow mask material plate is made larger than the surface roughness of the width direction center, and preferably continuously changes from the width direction center to the width direction end. When the negative original is brought into close contact with the photosensitive film on the surface of the shadow mask material plate by vacuum adhesion, the photosensitive film and the negative original are brought into close contact from their central parts, and the adhesion proceeds toward the peripheral part. The negative original plate can be completely formed on the photosensitive film in a short time. Therefore, by distributing the surface roughness within a range that does not deteriorate the electron beam passage hole, it is possible to produce a shadow mask having a good hole shape without causing unevenness in the electron beam passage hole diameter, and to improve the productivity. Can be improved.

[Brief description of the drawings]

1 and 2 are explanatory views of an embodiment of the present invention. FIG. 1 is a sectional view of a material plate for a shadow mask according to an embodiment of the present invention, and FIG. FIG. 3 is a diagram showing a change in roughness in comparison with the surface roughness of a conventional material plate for a shadow mask, FIG. 3 is a diagram showing a configuration of a color CRT, and FIG. 4 is a diagram showing a shape of an electron beam passage hole of the shadow mask. FIGS. 5 (a) and 5 (b) are a front view and a sectional view, respectively, showing the configuration of a vacuum contact printing apparatus. 20 …… Material plate for shadow mask 21a, 21b …… Both sides

Claims (2)

(57) [Claims] An electron beam passage hole is formed by a photo-etching method comprising a step of exposing a negative original plate to a photosensitive resin film formed on a surface of the plate material and comprising a plate material having a predetermined width and length. A material plate for a shadow mask, wherein a surface roughness at an end in a width direction of the plate material is greater than a surface roughness at a center portion in the width direction. 2. The material plate for a shadow mask according to claim 1, wherein the surface roughness of the plate material changes continuously from the center in the width direction to the end in the width direction.