JPS5922347B2 - Manufacturing method of color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the method of applying a light absorbing material to the inner surface of a face plate in the manufacturing process of a color picture tube.

Generally, the fluorescent surface of a color picture tube has three colored phosphors arranged regularly on the inner surface of the face plate, and a light absorbing film is formed between these phosphors.

To obtain such a fluorescent surface, first, a photosensitive resin film containing polyvinyl alcohol as a main component is formed on the inner surface of the face plate, and then the resin film in the area where the fluorescent material is planned to be disposed is removed through a shadow mask. Make it water-insoluble.

Next, remove the resin film from areas other than the area where the phosphor is planned to be placed, apply a light-absorbing substance, and then treat with hydrogen peroxide to place the resin film at the area where the phosphor is planned to be placed on top. The deposited light-absorbing material is also removed, and then the phosphor is deposited on the area where the phosphor is to be provided.

A conventional method of applying a light-absorbing substance is to apply a carbon suspension onto the inner surface of a face plate while appropriately holding and rotating the face plate.

The phosphorescent surface obtained in this way has a light absorption film with a thickness of approximately 0.7 μm, which not only allows the electron beam to pass through but also reduces the white uniformity of the screen. However, there is also an adverse effect of lowering the contrast ratio.

The present invention has been made in order to eliminate the drawbacks of the prior art, and is to manufacture a color picture tube that has a uniform coating of light-absorbing material with a sufficient thickness and a screen with good white uniformity and contrast ratio. The purpose is to provide a method.

In the method of the present invention, the method for holding the face plate has been improved.

As a result of experiments, it was discovered that it is necessary to hold the face plate with its central axis pointing downward at 15 degrees to 30 degrees with respect to the horizontal plane.

If the central axis is directed upward, it will not be possible to coat the side wall, and the same will happen if the central axis is at an angle of less than 15 degrees with respect to the horizontal plane.

If the angle is greater than 30 degrees, the coating solution will bubble and cannot be coated uniformly, especially on the side walls.

Therefore, in the present invention, the central axis of the face plate is held as described above.

The composition of the suspension was also improved in the method of the present invention.

That is, by adding an appropriate amount of thickener and dispersion to the carbon suspension, it is easy to apply, and the coating thickness is as thick as desired.
Made it even and stable.

For example, carbon stock solution (contains about 5.2% carbon), about 20% of the polyacrylate carbon stock solution, and an appropriate amount of Pluronic L-92 (trade name) as a dispersant.

Next, the coating method will be specifically explained.

゛As shown in the figure, the face plate 2 formed with photosensitive resin, exposed and developed as described above is held by suction on the tilting rotation holder 1, and the central axis 3 and horizontal surface 4 of this face plate 2 are
The angle θ between the two is set downwardly in the range of 15 to 30 degrees, and the rotation is performed at a rate of 50 revolutions per minute.

Then, in an atmosphere of about 100°C, the carbon suspension 5 described above is applied from the nozzle 6 to the center of the inner surface of the face plate 2 by about 1 inch.
Pour for a minute.

Then, the suspension 5 is uniformly applied to the inner surface of the face plate 2 due to gravity and the rotation of the face plate 2.

Moreover, since the suspension 5 is mixed with a thickener as mentioned above, it has an appropriate viscosity and can be applied to a desired thickness, and the action of the dispersant prevents the suspension 5 from agglomerating. Also for this reason, the coating is uniform.

In this coating process, about 5QQcc of the suspension 5 is poured, of which about 220CC is poured onto the face plate 2.
Adheres to the inner surface.

Therefore, when the coating work is completed, remove the face plate 2, dry it, wash it with hydrogen peroxide as described above, and dry it to remove the light-absorbing film that has come out in holes or lines in the area where the phosphor is planned. Can be formed.

The light-absorbing film thus obtained is about 1μ to 2μ,
, which solves the problems of white uniformity and contrast ratio.

Therefore, increasing the film thickness to 2 μm or more is not only meaningless in terms of characteristics, but also causes the light-absorbing material to peel off during the phosphor coating process.

As described above, in the method of manufacturing a color picture tube of the present invention, the face plate is held so that its central axis is within an angle range of 15 degrees to 30 degrees below the horizontal plane, and the thickener and dispersant are Since the light-absorbing material suspension containing the above-mentioned light-absorbing substance is applied to the inner surface of the face plate, the resulting light-absorbing film has a sufficient thickness and can be applied uniformly, resulting in improved white uniformity and contrast ratio. Problems can be solved.

[Brief explanation of the drawing]

The figure is an explanatory diagram of an embodiment of the method for manufacturing a color picture tube according to the present invention. 2...Face plate, 3...Central axis, 4...Horizontal surface, 5...Suspension liquid.

Claims (1)

[Claims] 1 Hold the face plate so that its central axis is within an angle range of 15 to 30 degrees below the horizontal plane, and apply a suspension of a light-absorbing substance containing a thickener and a dispersant to the inner surface of the face plate. A method for manufacturing a color picture tube, characterized by coating the color picture tube.