JPS6329947B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube for a light source used in display devices and the like.

With the diversification of displays, various giant display devices have been developed. As a method suitable for color display and video reproduction, each pixel of the three primary colors is
There is a method of replacing one cathode ray tube with a single cathode ray tube and using tens of thousands to hundreds of thousands of cathode ray tubes. Such a cathode ray tube is called a light source cathode ray tube, and can also be described as a light emitting device. An example of its structure is shown in FIG. In the figure, reference numeral 1 denotes a cylindrical glass tube body constituting a vacuum envelope, the face portion 2 of which is coated with one type of phosphor 3 that emits green, blue, or red light. There is. On the inner surface of the phosphor 3, an aluminum vapor-deposited film 4 called a so-called metal back is formed, and a graphite film 5 is further applied as an internal coating film for the purpose of electrical conduction. Reference numeral 6 denotes an electron gun for emitting electrons in response to a signal to cause the phosphor to emit light.

Next, a method of manufacturing such a cathode ray tube for a light source will be explained with reference to FIGS. 2a to 2c. First, a hydrofluoric acid aqueous solution, a sodium hydroxide aqueous solution,
and wash with pure water. Then, for example, a predetermined amount of an aqueous solution of barium acetate as an electrolyte is injected, and then a suspension of a predetermined phosphor 3 dispersed in an aqueous solution of water glass as an adhesive is injected, and the mixture is allowed to stand for a predetermined period of time. to precipitate the phosphor 3.

This state is shown in FIG. 2a. After the phosphor 3 is precipitated in this manner, the tube body 1 is tilted to discharge the supernatant liquid 11 and dried with dehumidifying air to complete the deposition of the phosphor 3.

Such a method is generally called a sedimentation method. After the phosphor 3 is deposited by the method described above, the above-mentioned metal backing is performed. However, if the phosphor 3 is directly vapor-deposited with aluminum, a continuous vapor-deposited film will not be formed. After forming a very thin organic film, aluminum is vapor-deposited. That is, first, the phosphor surface is moistened with pure water, etc., and most of the phosphor 3 is covered with a water film 7 as shown in FIG. 2b.
A very thin lacquer film 8 is formed on the water film 7 by spraying an organic solvent lacquer, such as toluene or ethyl acetate, whose main component is acrylic resin. Next, as shown in FIG.
Remove by 0. This is because when a lacquer film is formed on an area where the phosphor 3 is not coated, the aluminum film deposited on this area causes so-called blistering during the subsequent baking process, as shown in Figure 3, and the glass becomes glassy. This is done to prevent it from peeling off the wall.

Next, the fluorescent surface is dried using dehumidifying air or the like, and a graphite film 5 is applied to a predetermined area, which is similarly dried. Finally, aluminum is vapor-deposited to form an aluminum vapor-deposited film 4, and then the organic material used in forming the fluorescent surface is decomposed and removed by baking at about 400° C. to complete the formation of the fluorescent surface.

An electron gun 6 is further welded and sealed to the tube body 1 on which the fluorescent surface has been formed, and then the inside of the tube body 1 is evacuated to activate the electron gun 6.
The finished product shown in FIG. 1 is obtained.

In the peripheral wall part 12, commonly called the skirt part, of the light source cathode ray tube manufactured by the above method, in unnecessary areas, that is, in areas other than the phosphor surface of the part to which the phosphor 3 is attached, water flows out at a constant pressure. The lacquer film 8 is removed using pure water 10. However, in order to reduce the remaining portion of the lacquer film 8, if you try to trim it as close as possible to the area where the phosphor 3 is adhered with the pure water 10, capillary development will occur. For example, pure water may enter the adhered portion of the phosphor 3, or the lacquer film 8 may be stretched by the pure water 10, causing cracks. In order to prevent these inconveniences, if the trimming level is lowered using pure water 10, the remaining area of the lacquer film 8 on the peripheral wall portion 12 will increase, so the lacquer film 8 will be removed in that area in the baking process described above.
Due to the decomposition gas, the aluminum film 4 deposited in this area will blister as shown in FIG. 3, and will peel off from the glass peripheral wall 12. If this adheres to the upper part of the phosphor 3, the luminous efficiency will decrease, and if it adheres to the electron gun 6, it will cause problems such as causing sparks.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a cathode ray tube for a light source configured so that blistering of the aluminum film on the glass peripheral wall does not occur during the baking process.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 4, the glass tube body 1 has a circumferential wall portion 12 continuous from its face portion 2 for a predetermined length (for example, a length of approximately 20 mm when the diameter of the glass tube body 1 is approximately 25 mm). It is formed into a tapered shape (taper angle of about 1° to 2°) that widens toward the electron gun 6 side at the end.

In other words, a part of the phosphor is coated on the peripheral wall 2, which is commonly called the skirt part, other than the phosphor-coated part of the face part 2 of the cathode ray tube for the light source, and the decomposition gas of the lacquer film 8 in the baking process is prevented. This allows for scattering. In other words, part of the particulate phosphor is adhered to a peripheral wall portion continuous from the face.

Conventionally, a cylindrical glass tube with a diameter of about 25 mm has a part to which the phosphor 3 is attached, called a face part 2, on either side, and since the pipe peripheral wall part is a straight pipe, it is perpendicular to the face part 2. Moreover, since the glass surface has no irregularities and is a smooth surface, it was not possible to adhere the phosphor to the peripheral wall using the sedimentation method. As is clear from the figure, the tapered surface is formed over a length of approximately 20 mm. On the other hand, at a length of 20 mm or more from the tip, the lacquer film 8 is trimmed with pure water 10, so there is no remaining lacquer film and there is no fear of blistering, so it is not formed into a tapered shape.
That is, at a distance of 20 mm or more, it is parallel to the axis of the glass tube 1 and perpendicular to the face portion 2.

The phosphor deposition method is the same as the conventional method,
First, the inner surface of the tube body 1 to which the phosphor 3 is attached is cleaned using a hydrofluoric acid aqueous solution, a sodium hydroxide aqueous solution, and pure water. After that, an aqueous solution of barium acetate as an electrolyte was injected into the entire tube at 0.05% of the total liquid volume, and the concentration of SiO ₂ in the prescribed phosphor 3 and water glass aqueous solution was adjusted to 0.7% of the total liquid volume in the tube. Inject a suspension of mixed and dispersed substances. Then, leave it to stand for about 15 minutes to precipitate the phosphor. In this case, since the peripheral wall portion 12 is formed in a tapered shape,
Fluorescent fine particles will adhere to it. After the phosphor 3 is deposited, the tube body 1 is tilted to complete the deposition of the phosphor 3. At this time, the particulate phosphor is adhered to and remains on the peripheral wall portion 12. The subsequent steps of forming the lacquer film 8 and forming the aluminum film 4 are no different from the conventional method.

When part of the fine particles adhere to the peripheral wall portion 12 as described above, a pinhole h is formed at the tip of the phosphor 3 adhered portion after the lacquer film 8 and the aluminum vapor deposited film 4 are formed, as shown in FIG. Therefore, during the baking process, the decomposition gas 13 of the lacquer film does not cause blistering on the aluminum film and causes pinholes.
It scatters from.

The above embodiment describes a cylindrical straight tube light source cathode ray tube with a diameter of approximately 25 mm, but the light source cathode ray tube according to the present invention may have a face portion having various shapes as long as it has a peripheral wall as a light source element. It can be applied to things. In addition, as a method for coating the peripheral wall with a phosphor, all precipitation coating methods other than the combination of barium acetate and water glass can be applied.

As explained above, according to the cathode ray tube for a light source according to the present invention, blistering of the aluminum film on the side wall due to the decomposition gas of the lacquer film in the baking process is eliminated, and the aluminum film is removed in the subsequent process. Decrease in brightness of fluorescent surface due to peeling,
Problems such as adhesion to the electron gun and sparking are eliminated, and it can greatly contribute to improving process yield and reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a cathode ray tube for a light source;
2a to 2c are explanatory diagrams of the manufacturing process of a cathode ray tube for a light source, FIG. 3 is a sectional view of a main part showing the blistered state of the aluminum film after the baking process, and FIG. FIG. 5 is an enlarged cross-sectional view showing the main parts of the cathode ray tube according to the present invention, FIG. FIG. 3 is an explanatory diagram showing a state in which the decomposed gas of the lacquer film scatters without causing blisters on the aluminum film in the baking process. 1...Glass tube body, 2...Face portion, 3
...fluorescent body, 6...electron gun, 12...peripheral wall section. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A cathode ray tube for a light source, which has a fluorescent surface on at least one end face of the tube body of a glass tube constituting a vacuum envelope, and an electron gun sealed at the other end, in which a phosphor is precipitated in the face part. A cathode ray tube for a light source, which is coated by a coating method, is characterized in that the peripheral wall of the vacuum envelope that is continuous from the face portion is formed in a tapered shape that widens toward the electron gun side at the other end by a predetermined length. Cathode ray tube for light source.