JPH07220631A - Method of forming fluorescent film - Google Patents

Abstract

PURPOSE:To get a cathode-ray tube long in life and also, reduce the power consumption sharply. CONSTITUTION:In a process of forming a fluorescent film 5 on the inner face of the face part 1a of a bulb 1 by sedimentation, the fluorescent film 5 is dried, and then it is soaked in water again, and hot blast 8 is blown against it. The temperature of the hot blast 8 shall be not less than the temperature equivalent to the disconnection energy of water molecules. Hereby, the gas molecules discharged during a heat treatment process decrease, and the gas molecules remaining in a bulb at the time of a cathode-ray tube being completed are reduced. Moreover, the vacuum pollution inside the cathode-ray tube by the increase of currents of electron irradiation accompany in the progress of high brightness is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for manufacturing a cathode ray tube,
In particular, it relates to a fluorescent film forming step.

[0002]

2. Description of the Related Art The formation of a fluorescent film on the inner surface of a bulb is disclosed in JP-A-62-62.
-195827 gazette is performed in the process as described. As shown in FIG. 1, first, the face portion 1 a of the valve 1
Facing downward, the gelling agent 2 in which pure water is mixed with barium acetate is charged. After that, the phosphor suspension 3 in which the phosphor 4 is mixed with water glass whose specific gravity has been adjusted is added, and the bulb is left standing as it is. During this time, the phosphor 4 is deposited on the inner surface of the face portion 1a of the bulb portion 1, and the treatment liquid in the bulb becomes clear. Then, the treated waste liquid is drained while inclining the bulb 1, and then the fluorescent film deposited on the inner surface of the face portion 1a is dried. Then, an aluminum film is deposited on the fluorescent film. At this time, for the purpose of forming an aluminum vapor-deposited film that is as smooth as possible, film coating of an organic suspension is performed. Then, as shown in FIG. 2, the cathode ray tube is completed by performing a graphite film forming step 3, an aluminum film forming step 4, a heat treatment step 5, an aging step 6, and a reinforcing step 7.

[0003]

If gas molecules such as moisture remain in the constituent members including the phosphor and water glass in the completed cathode ray tube, the temperature inside the bulb rises during the operation of the electron gun. These gas molecules are released due to the impact of electrons on the inner wall, which deteriorates the vacuum in the cathode ray tube and deteriorates the electron emission characteristics. This is a major factor in shortening the life of the cathode ray tube. Therefore, as shown in FIG. 2, the heat treatment step 5 in the cathode ray tube manufacturing step is performed.
The gas molecules taken into the component are released as much as possible to reduce the gas molecules remaining in the valve.

In the heat treatment step 5, first, an in-air heating step 51 of heating the bulb in the air to remove the organic suspension applied on the fluorescent film is performed. The largest number of gas molecules released into the valve at this time is water vapor. These gas molecules are discharged from the neck to the outside of the valve, but the neck is so thin that the gas molecules released inside the valve are not easily released into the atmosphere, but some remain inside the valve. Resulting in. Then, when the bulb wall drops to room temperature, it re-adsorbs everywhere inside the bulb,
Part of it is taken in as crystal water. Therefore, finally, the vacuum evacuation step 5 for evacuating the inside of the cathode ray tube to a vacuum.
The gas molecules remaining in the valve in 3 are released into the valve again and discharged outside the valve. However, in the vacuum evacuation process 53, the sealing process 52 in which the electron gun is attached to the neck portion is performed in the previous process, and the exhaust pipe is extremely thin. Therefore, it becomes very difficult to discharge the released gas molecules, and it takes a long time to completely discharge them. Therefore, it is necessary to reduce the gas molecules remaining and adsorbed in the valve as much as possible before the evacuation step 53 is performed.

An object of the present invention is to provide a method for forming a fluorescent film which reduces moisture and the like taken into the fluorescent film during the formation of the fluorescent film and is less likely to be re-adsorbed. This allows
Since gas molecules such as moisture released into the bulb in the heat treatment step 5 are reduced, the vacuum in the cathode ray tube is improved, and a cathode ray tube having a long life can be manufactured.

[0006]

In order to solve the above problems, it is effective to reduce the amount of water in the fluorescent film before the heat treatment step. That is, in the present invention, after the phosphor is applied to the inner surface of the face portion of the bulb portion by the precipitation method and dried, water is again put into the bulb and left to some extent. After draining the water, a gas inlet pipe is inserted into the valve from the neck portion and gas is blown to the valve. It is characterized in that the spraying temperature at this time is equal to or higher than the temperature corresponding to the desorption energy at which water molecules are easily desorbed and released. Specifically, since the desorption energy of water is around 120 ° C., the temperature of the hot hot air may be 120 ° C. or higher. It should be noted that the temperature is preferably 150 ° C. or higher to further accelerate the release of water molecules. As the gas to be introduced, a gas having a small water content, for example, dry air, dry nitrogen, dry argon or the like is more effective.
Further, it is also effective to make the tip of the gas introduction tube have a wide-mouthed structure or to rotate it so that hot air is blown to the entire fluorescent film.

[0007]

In the manufacturing process of the cathode ray tube, the phosphor is applied to the inner surface of the face portion of the bulb portion by the precipitation method together with water glass which plays the role of an adhesive, and is dried. When the phosphor is coated and then dried, the water glass that functions as an adhesive releases SiO ₂ and hardens. Carbon dioxide reacts with the water remaining in the fluorescent film to react with carbonate ions (CO ₃ ~)
Thus, SiO ₂ is liberated from the water glass and a carbonate (Na ₂ CO ₃ , K ₂ CO _3, etc.) is formed. When carbonate is heated, a large amount of gas is released near 100 to 300 ° C. Therefore, it becomes a large gas source in the heat treatment process as shown in FIG. Therefore, since carbonates are hygroscopic and easily dissolved, the carbonates are dissolved by re-immersing them in water after drying, and then high-temperature hot air is blown to efficiently evaporate the water, so that the water remains on the fluorescent film. prevent.

[0008]

EXAMPLES Examples of the present invention will be described below. A fluorescent film is formed in the process shown in FIG. First, as shown in FIG. 1, a phosphor is applied by precipitation. First, the face portion 1a of the valve 1
Is turned downward, and the gelation accelerator 2 in which pure water is mixed with barium acetate is added. Then, the specific gravity of the water glass, which plays the role of an adhesive between the phosphors and between the phosphors and the glass, is adjusted, and the phosphor suspension 3 in which the phosphors are mixed is added and allowed to stand. During this time, the phosphor 4 is deposited on the inner surface of the face portion 1a of the bulb 1, and the processing waste liquid in the bulb becomes clear. Next, the treated waste liquid is drained while the valve 1 is tilted, and the fluorescent film is dried. After the fluorescent film is dried, it is immersed in water again.
After soaking it to some extent, the water is drained and hot hot air is blown as shown in FIG. A gas introduction pipe 7 is inserted into the valve 1 from the neck portion 6 of the valve 1 and hot air is blown. It is important that the gas for blowing does not contain water like dry air, and dry nitrogen or dry argon can also obtain the same effect. Also, except for the cost, a rare gas such as dry helium, dry neon, or dry krypton may be used. Further, in order to prevent the formed fluorescent film from peeling off, water may be atomized and sprayed. Then, in a process as shown in FIG. 2, a graphite coating 3, an aluminum film deposition 4, a heat treatment process 5, an aging process 6 and a reinforcing process 7 are performed to complete a cathode ray tube.

According to the present invention, gas molecules, especially water molecules, released from the fluorescent film are reduced, so that gas molecules released into the bulb during the heat treatment process are reduced. Therefore, the gas molecules released into the valve can be easily exhausted, and the inside of the valve can be closed with a higher vacuum than before. As a result, vacuum contamination in the cathode ray tube due to an increase in electron emission current due to higher brightness is reduced, which further extends the life of the cathode ray tube.

[0010]

INDUSTRIAL APPLICABILITY The present invention reduces gas molecules such as moisture taken into the surface or inside of the fluorescent film constituting the cathode ray tube. Further, it forms a surface that is difficult to be re-adsorbed.
This reduces the gas molecules released in the heat treatment process. Therefore, when the cathode ray tube is completed, the number of gas molecules remaining in the bulb is reduced, and a higher vacuum cathode ray tube can be obtained. In other words, the cathode ray tube has a long life and little change in electron emission characteristics over time. Furthermore, vacuum contamination in the cathode ray tube due to an increase in electron emission current due to future high brightness can be reduced. In addition, due to the reduction of gas molecule emission from the fluorescent film and the graphite film, in the heat treatment process that was performed to make the inside of the valve high vacuum, the heating temperature of the valve part during the vacuum exhaust process was changed. The temperature can be lowered and the time history can be shortened, and the power consumption can be greatly reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view of a fluorescent film forming process according to the present invention and the related art.

FIG. 2 is a flowchart showing a manufacturing process of a cathode ray tube.

FIG. 3 is a flowchart showing steps of forming a fluorescent film of the present invention.

FIG. 4 is a side sectional view of a bulb for explaining hot air blowing on a fluorescent film after immersion in water according to the present invention.

[Explanation of symbols]

1 ... Bulb, 1a ... Face part, 2 ... Gelation accelerator, 3
... phosphor suspension, 4 phosphor, 5 phosphor film, 6 neck, 7 gas inlet tube, 8 hot air.

Claims (1)

[Claims] 1. A gelling accelerator is put into the bulb, and then a suspension of the phosphor in which the phosphor is dispersed is placed and allowed to stand to precipitate the phosphor on the inner surface of the bulb. In the step of draining the processing waste liquid in the bulb and drying the fluorescent film to form the fluorescent film, the processing waste liquid in the bulb is drained and the fluorescent film dried at high temperature is again immersed in water to obtain hot hot air. A method for forming a fluorescent film, characterized in that the spraying is performed at a temperature of the high-temperature hot air at a temperature higher than the temperature corresponding to the desorption energy of water molecules contained in the fluorescent film.