JPH04277440A - Manufacture of cathode ray tube - Google Patents

Abstract

PURPOSE:To reduce the amount of rare gas and hold the electron emitting characteristics in good performance for a long period of time by heating a getter in the evacuating process at a temp. hither than the max. temp. of the body of a cathode ray tube concerned at the time of evacuation and lower than the activation temp. of the getter. CONSTITUTION:To remove rare gas such as Ar adsorbed to getter in the evacuating process, the getter is subjected to a heating process in the condition that the temp. of a cathode ray tube concerned within an evacuation furnace has passed the max. region and sunk therefrom. This is made with the conventional high frequency induction heating method, in which a 450 deg.C heating is conducted for three min. Thereby approx. 95% of the gas contained and/or adsorbed by the getter can be removed. The gas released from the getter into the cathode ray tube is sucked by the evacuation system quickly and discharged to outside the tube. This greatly reduces the residual amount of the gas of Ar, etc., which is inert and has a large molecular weight, in the cathode ray tube after the evacuation pipe was cut sealedly and a getter flush was performed, and the electron emitting characteristic of the cathode can be maintained in good performance for a long period of time. Thus the cathode ray tube as resultant product will be equipped with a long lifetime and high reliability.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention improves the ability to maintain vacuum inside the tube of cathode ray tubes, especially color cathode ray tubes that have many members that may become gas emission sources after being put into practical use. The present invention relates to a method for manufacturing a cathode ray tube that can maintain good electron emission characteristics over a long period of time.

0002

[Prior Art] In order to create a high vacuum inside the tube (bulb) of a cathode ray tube, during manufacturing the entire cathode ray tube is made of glass, which is made up of a cathode ray tube, and in particular, in the case of a color tube, a glass plate is used to secure the panel and funnel. While maintaining the temperature near the maximum temperature that the sealing part made of melting point glass can withstand for a considerable period of time, the exhaust pump evacuates the residual gas in the tube until the pressure of the gas is sufficiently low. However, as is well known, even if the gas pressure inside the tube is lowered only through the exhaust process during manufacturing, the tube of a cathode ray tube contains many members that are constantly exposed to electron beam impact during actual use. Since members become hot during use, it is unavoidable that gases that have been adsorbed or occluded are gradually released from the surfaces of those members during use. It is also known to use getters to adsorb such gases and keep the gas pressure in the cathode ray tube low.

Conventionally, when manufacturing cathode ray tubes, after finishing the exhaust work and sealing off the exhaust pipe connecting the cathode ray tube and the exhaust pump, the getter was heated to about 850 to 1300°C using high frequency heating or the like. The barium atoms constituting the getter were scattered inside the cathode ray tube to form a getter film on the inner wall surface of the cathode ray tube. This getter film made of barium adsorbs the residual gas inside the tube and reduces the vacuum inside the tube to 10￣4T.
orr to 10￣7 to 10￣8Torr (1 Pa
= (1/133) Torr), and as a result, the electron emission characteristics from the cathode could be maintained well.

[0004] Among the methods for manufacturing cathode ray tubes, techniques related to this type of getter are described in, for example, Japanese Patent Publication No. 1-1-1.
Japanese Patent No. 23896 describes a method for surely flashing the getter.

[0005]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, after the sealing is broken and the cathode ray tube is put into practical use, gases remaining in the cathode ray tube that are not absorbed by the getter film, especially It has been found that there is a problem in that rare gases such as argon, which have a large molecular weight almost equal to that of air, often remain.

[0006] There are two types of argon: argon that was originally contained in the cathode ray tube remains, and argon that is adsorbed by the getter and released into the cathode ray tube when the getter is flashed. Conventionally, more than half of the rare gas such as argon remaining in the tube during getter flashing was adsorbed by the getter, and the argon released into the tube in this way was ionized and sent to the cathode. destroys the electron emitting layer of In particular, when an impregnated cathode is used as an electron emission source, the barium in the surface layer of the substrate made of porous sintered tungsten is consumed, reducing the electron emission ability (Reference: Journal of Japan Society of Applied Physics 56 No. 11 (19
87) pp. 1423-1432). Particularly in in-line color cathode ray tubes, the electron emission layer of the central electron gun undergoes a large amount of wear, so when the central electron gun is normally used for green, there is a problem in which the screen turns magenta to red for a while when the switch is turned on. . In addition, the above argon gas is
It is thought that the substance used to protect barium, which easily combines with oxygen, from oxidation during the getter manufacturing process was adsorbed during the process and remained.

The present invention is directed to a cathode ray tube that reduces the amount of a rare gas with a large molecular weight, such as argon, that is adsorbed by the getter and is brought into the cathode ray tube, thereby making it possible to maintain the electron emission characteristics of the cathode well over a long period of time. The purpose is to provide a manufacturing method.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a flash getter in an amount sufficient to absorb the gas released from each member into the bulb of the cathode ray tube after the seal is cut. In the manufacturing method for cathode ray tubes that are installed inside the tube, during the normal exhaust process in which the entire cathode ray tube is heated and the gas inside the tube is exhausted while the temperature is rising, the temperature of the cathode ray tube body shifts from the highest temperature range to the lower temperature range. In the process, it was decided to additionally heat the getter at a temperature higher than the maximum temperature during exhaust of the cathode ray tube body and lower than the activation temperature of the getter.

[0009]

[Effect] Specifically, the above heat treatment is performed during the evacuation process of the cathode ray tube, when the main body temperature of the cathode ray tube passes through the maximum temperature range and shifts to the temperature drop range, and the pressure of the gas remaining inside the tube is reduced to the previous level. Due to exhaust work, 10￣3Torr (≒10￣1
Pa), the getter is usually heated using a high-frequency induction heating device. The heating temperature of the getter in this process must be at least higher than the maximum temperature of the getter part of the cathode ray tube in the exhaust process in order to release the adsorbed rare gas, and the upper limit of the heating temperature is The reaction between the nickel/aluminum and barium contained therein rapidly occurs, and it is necessary to suppress the temperature below the temperature at which the getter evaporates (getter flash) due to the reaction heat (activation temperature). Activation temperature is generally 80
Since the temperature is about 0°C, the appropriate getter heating temperature in the above heat treatment is 300 to 750°C. It has been found that rare gases such as argon adsorbed and contained in the getter can be almost removed by heating at 200 to 300° C., and the above heating temperature is necessary and sufficient.

The degree of vacuum inside the tube during heating is determined by the reaction between the barium in the getter and the residual gas inside the tube. If the residual gas pressure in the tube is 10-1 Torr or more, the reaction between the residual gas in the tube and the getter progresses due to the release of argon gas from the getter, making it impossible to form a good getter film during getter flash. However, the residual gas pressure in the pipe is 10￣3To
If we decide to carry out the heat treatment under the conditions of rr or less,
The above-mentioned inconvenience will no longer occur.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a flowchart showing the main parts of the manufacturing process of a cathode ray tube according to the present invention, and FIG. 2 shows a flowchart showing the main parts of a conventional manufacturing method for reference.

After the stem supporting the electrodes of the electron gun of the cathode ray tube is welded and sealed to the end of the neck tube of the bulb, the valve is evacuated. In the exhaust process, a cathode ray tube is attached to the top of a trolley equipped with an exhaust system consisting of a rotary pump and a diffusion pump, and the cathode ray tube is heated inside the exhaust furnace, and the entire trolley is moved inside the long exhaust furnace. Exhaust the air while moving. The getter heat treatment according to the present invention for removing the rare gas such as argon adsorbed on the getter is carried out in a state where the temperature of the cathode ray tube in the exhaust furnace has passed the maximum range and has been decreasing thereafter. The reason for performing this when the temperature is falling is that if the evacuation has progressed to this point, the degree of vacuum within the cathode ray tube has improved to a state suitable for performing the heat treatment. The getter is heated to approximately 450°C using the usual high-frequency induction heating method.
Heat for 3 minutes. This makes it possible to remove about 95% of the gas contained and adsorbed in the getter material. The gas released into the cathode ray tube from the getter is quickly sucked into the exhaust system and exhausted outside the tube. Thereafter, the exhaust pipe connecting the cathode ray tube and the exhaust system is melt-sealed and sealed (chip-off). After the exhaust process is completed, the getter is heated to about 800°C from outside the tube using high-frequency induction heating to cause a reaction between nickel and aluminum, and the reaction heat is used to raise the temperature to about 1300°C, and the getter material is exposed to cathode rays. The getter film is dispersed into the tube to form a getter film at a desired position on the inner surface of the valve wall.

In the conventional exhaust method, after the getter flash, molecular weight molecules such as argon remained in the electron beam path in the cathode ray tube without being absorbed by the getter film, and were ionized during practical use, causing destruction of the electron emission layer of the cathode. The amount of residual large inert gas can be reduced to less than half that of the conventional method using the manufacturing method of the present invention. Therefore, the electron emission characteristics of the cathode are maintained in a good state for a longer period of time than in the past. In an in-line color cathode ray tube, the cathode of the central electron gun receives more ion bombardment than the cathodes of the electron guns on both sides, which tends to cause color imbalance when switched on. Normal color cathode ray tubes use a central electron gun for green, which has high visibility, and electron guns on both sides for red and blue, but unlike conventional color cathode ray tubes, the residual gas inside the tube contains a lot of argon. In this case, electron emission from the central electron gun is suppressed to a relatively low level during switch-on, and
The screen for the first few seconds was red to magentaish. Such a phenomenon was not observed in the cathode ray tube manufactured according to the present invention.

[0014] The temperature of the getter heat treatment performed in the present invention is as follows:
Any number of times is acceptable as long as the temperature is below the activation temperature of the getter, but in reality, there is almost no effect if the temperature is below the degassing temperature during the evacuation process of the cathode ray tube. Therefore, a temperature of 300 to 750°C is appropriate. Also, the higher the degree of vacuum inside the tube during heat treatment, the better.
If the residual gas pressure exceeds 10￣1 Torr, the residual gas in the tube will react with the getter (barium), and the reaction between aluminum and nickel during getter flash will not proceed smoothly, or the amount of barium effective as a getter film will decrease. So I don't like it. Normally, the residual gas pressure in the pipe is 10￣4 to 10￣5T by exhausting with a rotary pump and a diffusion pump.
When the temperature is below orr, heating is performed to reduce consumption of the getter material during the heat treatment process due to residual gas in the tube to below 100 ppm.

[0015]

As explained above, according to the present invention, the residual amount of inert, large molecular weight gas such as argon is reduced in the cathode ray tube after the exhaust pipe is sealed and the getter flash is performed. Furthermore, the getter wear is reduced during getter flash, and ion bombardment to the cathode is reduced, and the electron emission characteristics of the cathode are maintained well over a long period of time, resulting in a highly reliable cathode ray tube with a long life. can get. In addition, in the case of an in-line color cathode ray tube,
Conventionally, the electron emission characteristics of the cathode of the central electron gun were reduced to 1/1 of those of the cathodes of the electron guns on both sides due to ion bombardment.
The present invention lowered the value to about 2, but the present invention brought it to the same level.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of main parts of a cathode ray tube manufacturing process according to the present invention.

FIG. 2 is a flowchart of main parts of a conventional cathode ray tube manufacturing process.

Claims (1)

[Claims] Claim 1: A method for manufacturing a cathode ray tube in which a flash getter is installed inside the tube to absorb gas emitted inside the bulb of the cathode ray tube, in which the entire cathode ray tube is heated and the gas inside the tube is exhausted at an elevated temperature. During the evacuation process, during the process in which the temperature of the cathode ray tube body passes through the maximum temperature range and moves to the temperature drop range, the getter is heated to a temperature that is higher than the maximum temperature during exhaust of the cathode ray tube body and lower than the activation temperature of the getter. 1. A method for manufacturing a cathode ray tube, characterized by adding a heating process.