JPS5833647B2 - Cathode ray tube manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing cathode ray tubes, such as color television picture tubes.

In cathode ray tubes such as color television picture tubes,
A cathode ray tube is manufactured by inserting an electron gun into the neck of the tube body, which has a phosphor surface with phosphors of each color painted in a predetermined pattern on the inside of the panel, evacuating the inside of the tube, and sealing it. However, in this case, after the cathode ray tube is completed, it may be detected that the completed cathode ray tube is a defective product due to, for example, poor emission of the cathode.

In this case, the panel-funnel side, which has a defect-free colored fluorescent surface on its inner surface, can be recycled and reused, cut at the neck, replace the electron gun with another electron gun, and re-open the inside of the tube. Often, the exhaust is sealed for regeneration.

However, in cathode ray tubes obtained by remanufacturing defective cathode ray tubes, that is, regenerated tubes, dotted shadows, so-called omissions, often occur in the cathode image.

As a result of various experiments and considerations, the inventor of the present invention has determined that the cause of "dropping" in the cathode image in such regenerated tubes is due to the fact that the tube used in the previously completed tube is inside the tube to be regenerated. It was discovered that barium Ba as a getter material had an effect.

That is, in this type of cathode ray tube, it is necessary to maintain a high degree of vacuum inside the tube, so a getter material is deposited inside the cathode ray tube to adsorb the gas remaining inside the tube. It was discovered that the presence of barium as a material causes the generation of hydrocarbons such as methane and ethane, which will be described later, and that this deteriorates the properties of the cathode.

To explain further, when trying to regenerate a defective cathode ray tube, the tube is first leaked and air is introduced into the tube.
Oxygen and water in the atmosphere and barium as a getter material deposited inside the tube to be regenerated cause the following equations (1) and (2) to react, resulting in hydroxylation of Ba(OH)2, etc. It becomes barium.

2Ba+02→2BaO・・・・・・・・・・・・(1
) B a O+H2 Ishu a (OH)2-(2) On the other hand,
In the regeneration tube, when barium getter material is scattered to make the inside of the tube high vacuum again, the carbon dioxide gas CO9CO2 remaining in the tube and Ba react according to the following equations (3) and (4), Barium carbide BaC2 is produced.

2Ba+2CO-+2BaO-f-BaC2"...(3
)5Ba+2CO2→4BaO+BaC2="(4) And the BaC2 thus generated and the above (2)
A chemical reaction occurs between the Ba(OH)2 and the reaction shown in the following formulas (5) to (8) to produce methane CH4.
, resulting in hydrocarbons such as ethane C2H6.

Ba(OH)2+BaC, )2BaO+2(CH)
・・”−(5)Ba(OH)2+Ba→2BaO+2(
H) = (6) (CH) + 2[H4......(
7) 2 (CH)+4H-)C2H6...(8) Then, a large amount of the hydrocarbons generated in this way is present in the tube. The impact of the beam sputters the surface of the cathode, creating holes in the cathode material layer, which results in the occurrence of cathode image voiding.

Therefore, in order to avoid this deterioration of cathode properties, it is sufficient to minimize the generation of hydrocarbons.

And even if this hydrocarbon is not barium hydroxide, it is H2
For example, methane CH4 is generated from 0 to 0, but in the case of a regenerated tube, there is a large amount of H20 source in the form of barium hydroxide in the tube due to the reaction of equation 2 (as described above), so there is less carbonization than in a new tube. The rate of hydrogen generation is extremely high, which is why the above-mentioned cathode image leakage occurs at a much higher rate than in new tubes.

Based on this investigation, the present invention attempts to avoid the generation of hydrocarbons that degrade the cathode properties.

The present invention will be described in detail below with reference to the drawings.
As shown in the figure, a cathode ray tube 1 that is sealed in a high vacuum and is to be recycled as a defective product is leaked and the inside of the tube is maintained at atmospheric pressure, and then its neck portion 1a is cut at the required position shown by the chain line A. Then, the defective electron gun 2 placed inside the neck portion a is taken out.

Thereafter, the tube 1' to be regenerated, which consists of at least the panel 1b and the funnel part 1c, of the defective cathode ray tube 1 is heated in carbon dioxide gas CQ20, preferably carbon dioxide gas CO2 containing moisture.
Temperature at which the tube body does not soften in the gas, e.g. 380℃
Heat treatment is performed for 20 minutes.

In this way, the barium hydroxide deposited on the inside of the pipe to be regenerated reacts with carbon dioxide gas to form stable barium carbonate.

That is, the following reaction (9) occurs.

Ba(OH)2+CO2→BaO+BaCO3・・・・
(9) B a COa thus produced is an extremely stable compound that can only be decomposed at a high temperature of, for example, 700°C to 800°C.

After performing such a heat treatment, a new electron gun 2' including the tube body 111 is inserted into the neck part of the tube, and the electron gun 2 is removed.
Tip-off tube 4 with attached stem 31
Evacuate while baking.

Baking at this time of evacuation is carried out by heating to 400° C. at a temperature increase rate of 6° C. per minute, for example.

Thereafter, the inside of the tube is sealed by tip-off with a tip-off tube, and a gettering operation is performed by vapor-depositing a new getter material to maintain the inside of the tube at a high degree of vacuum.

It has been confirmed that cathode ray tubes using regenerated tubes obtained in this manner have almost no accident in which the cathode image is missing.

By the way, in the conventional regeneration tube, the partial pressure of CH4 is 1O
``It was about 10-91 torr, whereas it was about 10-91 torr by the method of the present invention.

As mentioned above, according to the manufacturing method of the present invention, even in regenerated tubes, the rate of cathode image omission can be reduced, and the rate of defective products can be drastically reduced, resulting in enormous industrial benefits.

[Brief explanation of drawings]

FIGS. 1 and 2 are route maps of each step of an example of the manufacturing method of the present invention. 1 is a defective cathode ray tube, 2 is its electron gun, 1' is the tube body to be regenerated, 2' is a new electron gun, 3 is a stem, and 4 is a tip-off tube.

Claims (1)

[Claims] 1. Obtaining a cathode ray tube by heating the tube to be regenerated in carbon dioxide gas, then inserting an electron gun into the tube, baking it, performing exhaust treatment, and sealing it. A method for manufacturing a cathode ray tube.