JP2000048719A - Method and device for sealing impregnation type cathode electron gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing method for an impregnation type cathode electron gun capable of securely preventing oxidization of the impregnation type cathode caused by a heating treatment in an electron gun sealing process, and a sealing device for the impregnation type cathode electron gun having an inexpensive and simple structure which can be applied to the method of the same. SOLUTION: In this electron gun sealing method for sealing an electron gun 5 using an impregnation type cathode to an electron tube, a neck glass 13 of the electron tube and a stem glass of the electron gun 5 are preheated so as to be welded to each other. By heating and blowing non-oxidizing gas 20 from hot air heaters 16 for preheating, the neck glass 13 and the stem glass are preheated to be heated and welded to each other in an atmosphere of non- oxidizing gas, by which the electron gun 5 is sealed to the above electron tube. In addition, in this device, the preheating means for preheating the neck glass 13 of the above electron tube and the above stem glass of the electron gun 5 is structured by the hot air heaters 16, to which a non-oxidizing gas supply device 18 is connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube such as a cathode ray tube or an image pickup tube, or an electron tube which can be widely used as a microwave tube, a traveling wave tube, a magnetron, a laser tube, etc. for a satellite, and more specifically, an impregnated cathode. The present invention relates to a method and an apparatus for sealing an impregnated cathode electron gun, which can prevent oxidation of an impregnated cathode generated in a step of sealing the electron gun when manufacturing an electron tube having the used electron gun.

[0002]

2. Description of the Related Art An outline of a conventional method for sealing an electron gun in an electron tube will be described with reference to FIGS. As shown in FIGS. 5 and 6, a cathode ray tube 1, which is one of the electron tubes, heats a glass panel 3 coated with a fluorescent screen 2 and a glass funnel 4 coated with an inner surface tag during the manufacturing process. After sealing, it is manufactured by heat sealing the electron gun 5 to the neck of the funnel 4.

The electron gun 5 has an oxide cathode 6 for emitting electrons as shown in FIGS.
Is usually composed of a composite carbonate layer of an alkaline earth metal composed of barium, calcium, strontium and the like. The oxide cathode 6 of the electron gun 5 is generally composed of an alkaline earth metal ternary carbonate powder (Ba, Sr, Ca) CO such as barium, calcium, strontium, etc., which serves as an electron emitting material layer on the surface of the nickel base metal 7. It is formed by applying ₃ by a spraying method or the like.

In general, a Fraun tube 1 formed by heat sealing an electron gun 5 is, as shown in FIG. 9, after a sealing step of the electron gun 5, an evacuation step of evacuating to a high vacuum while performing a heat treatment, and then an explosion-proof treatment. A finished product is obtained through a process and an activation process for emitting electrons from the oxide cathode 6. However, with the recent increase in the size of cathode ray tubes, a cathode having a high current density and a long life, which cannot be achieved by the conventional oxide cathode 6 made of ternary carbonate, has been desired. An impregnated cathode 8 as shown in FIG. 10, which is used for a laser tube or the like, has been used for a cathode ray tube 1.

The impregnated cathode 8 generally includes an electron emitting material 10 such as barium oxide BaO, calcium oxide CaO, or alumina Al ₂ O ₃ inside a base metal 9 made of porous tungsten as shown in FIG. The impregnated cathode 8 is formed by melting and impregnating at an appropriate ratio.
There is also a configuration in which iridium, osmium, ruthenium, or the like is coated thereon after impregnation with 0. These impregnated cathodes 8 are heated by a heater 11 provided at the lower part during operation of the cathode ray tube, barium 12 seeps out of the impregnated portion, and electrons are emitted from the barium 12 that seeps out.

However, the impregnated cathode 8 is very susceptible to oxidation, and it is an important issue how to prevent the impregnated cathode 8 from being oxidized during the cathode ray tube manufacturing process. Moreover, electron emission substance 10 impregnated is easily hydroxide Ba (OH) ₂ becomes bonded to the moisture contained in the air, in the worst case, it may proceed to carbonate BaCO _3. On the other hand, the porous tungsten constituting the base metal 9 is also a substance that easily oxidizes due to heat and deteriorates.

When the impregnated cathode 8 is oxidized and deteriorated as described above, the electron emission ability is extremely reduced. Therefore, the impregnated cathode 8 is usually removed as an inspection failure. After the device enters the market, the electron emission capability gradually deteriorates during operation of the cathode ray tube, and the life may be extremely shortened. For this reason, it is necessary to keep the impregnated cathode 8 from being exposed to the atmosphere as much as possible after its production. The storage and transportation of the assembled electron gun 5 is performed by vacuum packing, and the production line up to vacuum evacuation of the cathode ray tube 1 is performed. The temperature and humidity are adjusted to prevent oxidation and deterioration of the impregnated cathode 8.

On the other hand, in the manufacturing process of the cathode ray tube 1, a process of sealing the electron gun 5 by heat is inevitable.
Here, too, since it is exposed to an environment that is easily oxidized, how to prevent oxidation and deterioration of the impregnated cathode 8 in this sealing step is the biggest issue. Therefore, in order to prevent oxidation and deterioration of the impregnated cathode 8 in the sealing step of the electron gun 5, for example, as shown in Japanese Patent Application Laid-Open No. 56-152135, a hole is formed in the neck portion of the cathode ray tube 1 such as nitrogen, argon or the like. For sealing by introducing a non-oxidizing gas described in
As disclosed in Japanese Patent No. 8918, a method of blowing a non-oxidizing gas through a chip tube glass for sealing, and a method of blowing nitrogen into the cathode ray tube 1 before the sealing step to replace with air and to seal. Proposed.

However, in any of these methods, it is difficult to apply the method to an actual manufacturing process,
It is a reality that the desired effect cannot be obtained or a satisfactory result has not yet been obtained. When sealing the impregnated cathode electron gun 5 to an electron tube such as a cathode ray tube 1,
There has been a demand for a method capable of reliably preventing oxidation and deterioration of the impregnated cathode 8.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to address the above problems, and a first object of the present invention is to provide an impregnated cathode caused by heat treatment in an electron gun sealing step. It is an object of the present invention to provide a method of sealing an impregnated cathode electron gun that can reliably prevent oxidation. Another object of the present invention is to provide an inexpensive and simple structure of an impregnated cathode electron gun which can be applied to the above-mentioned sealing method and can seal an electron gun without oxidizing the impregnated cathode in a sealing step. To provide a sealing device.

[0011]

In order to solve the above-mentioned problems, a method for sealing an impregnated cathode electron gun according to the present invention comprises a method of sealing an electron gun using an impregnated cathode in an electron tube. In the deposition method, the neck glass of the electron tube and the stem glass of the electron gun are preheated, and when heating and welding, a non-oxidizing gas is heated and blown from a preheating hot air heater,
The electron gun is sealed in an electron tube by preheating and heat welding in a non-oxidizing gas atmosphere, and when the electron gun is sealed, the neck glass of the electron tube and the electron tube are sealed. The stem glass of the gun is preheated and then welded by heat.However, since a large amount of hot air blown to the impregnated cathode during preheating is a non-oxidizing gas heated by a hot air heater, impregnation during preheating is performed. Since oxidation of the cathode can be prevented and sealing can be performed in a non-oxidizing gas atmosphere, oxidation and deterioration of the impregnated cathode in the sealing step can be reliably prevented.

Further, the sealing apparatus for an impregnated cathode electron gun according to the present invention is characterized in that a neck glass of the electron tube and an electron tube are arranged around a turntable for arranging and transporting the electron tube around which the electron gun is placed. In a sealing device for an impregnated cathode electron gun comprising a preheating means for preheating the stem glass of the gun and a glass fusion sealing burner for heating and fusing them, the preheating means comprises a hot air heater. The non-oxidizing gas supply device is connected to the same hot air heater, which is characterized in that at least a preheating burner of a gas burner usually used for preheating, slow cooling, etc. is heated air heater. By connecting a non-oxidizing gas supply device to this hot air heater, the heated non-oxidizing gas is sprayed on the impregnated cathode during preheating, and the impregnated cathode is heated in a non-oxidizing gas atmosphere. Since it is possible to perform the sealing of the child gun at a relatively simple configuration of only providing the warm air heater, it is possible to achieve the intended purpose.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
4 through FIG. FIG. 1 is a plan view showing a schematic configuration of a hot air heater of a sealing device for an impregnated cathode electron gun according to an embodiment of the present invention. FIG. 2 is a side view showing a flow of a non-oxidizing gas in the hot air heater. FIG. 3 is a plan view showing the overall configuration of the sealing device for the impregnated cathode electron gun according to the embodiment of the present invention, and FIG. 4 is a flowchart showing the sealing process for the impregnated cathode electron gun.

An embodiment of the present invention will be described below by taking as an example the case where a cathode ray tube 1 is manufactured. When the neck glass 13 of the cathode ray tube 1 and the electron gun 5 are sealed, first, the neck glass 13 and the stem glass 14 of the electron gun 5 are preheated, and when preheated, the glass is heated and melted by a gas burner for sealing. ing. Thereafter, in order to prevent cracking, the temperature is gradually lowered to gradually end the sealing step. For this preheating and slow cooling, a gas burner is generally used, and a hot air heater is used in part, and the glass is heated by these, but in the impregnated cathode 12 parts close to the sealing part, The temperature rises to a maximum of about 400 ° C.

In order to prevent oxidation of the impregnated cathode 12, the inventors have proposed a method of spraying a non-oxidizing gas such as nitrogen or argon onto the neck glass 13 and stem glass 14 and the impregnated cathode 12 from outside. Attempted, but when preheating with a gas burner, the cooling action of a large amount of non-oxidizing gas blown from the outside lowers the temperature of the glass, and blows out the gas burner, causing problems such as glass breakage And it turns out that this method does not work.

On the other hand, there is a heater using a hot air heater for preheating. In this case, a large amount of hot air is blown from the hot air heater for preheating to the impregnated cathode 12.
Focusing on this point, we noticed that if non-oxidizing gas such as nitrogen or argon is used instead of air blown as hot air, sealing by preheating and heat welding can be performed in a non-oxidizing gas atmosphere. According to the present invention, the oxidation of the impregnated cathode 12 during preheating can be prevented, and the neck glass 13 and the stem glass 14 can be sealed in a non-oxidizing gas atmosphere. Therefore, it has been found that the oxidation of the impregnated cathode 12 can be reliably prevented.

An embodiment will be described below with reference to the drawings. FIG. 3 is a plan view showing the overall structure of the sealing device for the impregnated cathode electron gun, in which a CRT 1 in which an electron gun 5 is inserted is arranged on a circumference and a turntable 1 which rotates in the direction of the arrow.
5 around which a plurality of burners or warm air heaters 16 for preheating and slow cooling and a burner 17 for glass melting and sealing are provided to constitute a rotary type fully automatic sealing device. I have.

When the electron gun 5 is sealed by this apparatus, the cathode ray tube 1 to be sealed and the electron gun 5 are first put into a predetermined position on the turntable 15 as shown in FIG. It is inserted into a predetermined position in the first neck glass 13. Next, a hot air heater 16 is used to prevent glass breakage.
Blows a non-oxidizing gas heated from the
The neck glass 13 and the stem glass 14 of the electron gun 5 are preheated. When the preheating is performed, the neck glass 13 and the stem glass 1
Then, sealing is performed by heat-welding No. 4 and then gradually cooled so as to gradually lower the temperature in order to prevent glass breakage.

Here, a hot air heater 16 is provided as a means for preheating the glass. The hot air heater 16 usually sucks in air from outside like a dryer, and heats the air to a certain temperature by an internal heater,
Although it is configured to blow it out as hot air, a non-oxidizing gas supply device 18 such as nitrogen or argon is connected to the hot air heater 16 so as to replace the air as shown in FIGS. The non-oxidizing gas is heated and blown into the air.

The hot air heater 16 has a non-oxidizing gas blowing section 19 as shown in FIGS.
A non-oxidizing gas supply device 18 is connected to the blowing section 19 so that the non-oxidizing gas 20 can be blown. A heater 21 is built in the hot air heater 16 and heats the blown non-oxidizing gas 20.
This is blown out from the outlet 22 as hot air gas 23 to heat the neck glass 13 of the cathode ray tube 1 and the stem glass 14 of the electron gun 5 and to blow it into the impregnated cathode 12.

According to the above embodiment, the non-oxidizing gas supply device 18 is connected to the hot air heater 16, the non-oxidizing gas 20 is heated by the heater 21, and the non-oxidizing gas 20 is blown out as the hot air gas 23. By blowing out from the nozzle 22, it blows on the neck glass 13 of the cathode ray tube 1 and the stem glass 14 of the electron gun 5, and also blows on the impregnated cathode 12 of the electron gun 5 to preheat these glasses and isolate the impregnated cathode 12 from oxygen. And the oxidation of the impregnated cathode 12 is prevented.

Therefore, according to the method for sealing the impregnated cathode electron gun described above, the impregnated cathode 12 can be reliably prevented from being oxidized by the oxidizing gas, and the cathode ray tube 1 of stable quality can be manufactured. can do. In addition, since the stabilization of quality can reduce the defect rate at the time of inspection and improve the yield, it is possible to reduce wasted time required to find the cause of the defect and improve productivity.
A great ripple effect can be expected, such as reduction in production cost.

Further, according to the sealing device of the impregnated cathode electron gun, since it can be easily carried out by using a conventionally used hot air heater, it is not necessary to use a large cost for the equipment. The above-mentioned sealing method can be realized by using an economical and inexpensive apparatus, and the initial purpose can be achieved. In the above embodiment, the manufacture of the cathode ray tube 1 has been described as an example. However, as described above, the present invention is applicable to a cathode ray tube such as a cathode ray tube or an image pickup tube, or a microwave tube for a satellite, a traveling wave tube, a magnetron, It can be widely applied to the manufacture of electron tubes such as laser tubes.

[0024]

As described above in detail, according to the sealing method of the impregnated cathode electron gun according to the present invention, the non-oxidizing gas heated by the hot air heater is blown, and the non-oxidizing gas atmosphere is blown. Preheating and heat welding can be performed while isolating the glass from the oxidizing gas, preventing oxidation of the impregnated cathode during preheating and heat welding, and impregnated cathode in the sealing step of the impregnated cathode electron gun. Oxidation and deterioration of the product can be reliably prevented, and the product quality can be improved and stabilized. Further, according to the sealing apparatus for an impregnated cathode electron gun according to the present invention, it is possible to provide an apparatus that can realize the above-described sealing method and that is economically and easily implemented.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of a hot air heater of a sealing device for an impregnated cathode electron gun according to an embodiment of the present invention.

FIG. 2 is a side view showing a flow of a non-oxidizing gas in a hot air heater of the sealing device of the impregnated cathode electron gun according to the embodiment of the present invention.

FIG. 3 is a plan view showing the overall configuration of a sealing device for an impregnated cathode electron gun according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a sealing step of the impregnated cathode electron gun according to the embodiment of the present invention.

FIG. 5 is an external perspective view showing a configuration of a conventional cathode ray tube.

FIG. 6 is a cross-sectional view showing an internal schematic structure of a conventional cathode ray tube.

FIG. 7 is a front view showing a configuration of a conventional electron gun.

FIG. 8 is an enlarged front view showing an oxide cathode of a conventional electron gun.

FIG. 9 is a flowchart showing a conventional cathode ray tube manufacturing process.

FIG. 10 is an enlarged front view showing the configuration of a conventional impregnated cathode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CRT, 5 ... Electron gun, 12 ... Impregnated cathode, 13
… Neck glass, 14… stem glass, 15… turntable,
16: hot air heater, 17: glass fusion sealing burner,
18 non-oxidizing gas supply device, 20 non-oxidizing gas

Claims (2)

[Claims] 1. An electron gun sealing method for sealing an electron gun using an impregnated cathode to an electron tube, comprising: preheating the neck glass of the electron tube and the stem glass of the electron gun; An impregnated cathode characterized in that the electron gun is sealed to an electron tube by heating and blowing a non-oxidizing gas from a hot air heater, preheating in a non-oxidizing gas atmosphere, and heat welding. How to seal the electron gun. 2. A preheating means for preheating a neck glass of the electron tube and a stem glass of the electron gun around a turntable for arranging and transporting the electron tube on which the electron gun is placed on the circumference.
In a sealing device for an impregnated cathode electron gun, which is provided with a glass fusion sealing burner for heating and welding them, the preheating means is constituted by a warm air heater, and a non-oxidizing gas is supplied to the warm air heater. A sealing device for an impregnated cathode electron gun, characterized by connecting devices.