Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2000-06-01
2003-05-20
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S041000, C445S045000
Reexamination Certificate
active
06565401
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cathode ray tube manufacturing method and a cathode ray tube manufacturing system which can increase a degree of vacuum in a cathode ray tube after getter flash.
2. Description of the Related Art
In the related art including Japanese Patent Unexamined Publication No. Sho. 57-67260, normally an inside of the cathode ray tube can be kept in a vacuum by sealing a tip tube, which is attached to an electron gun in the cathode ray tube, in an exhaust furnace to melt and seal it.
Then, in order to form a getter film which chemically adsorbs gas molecules of a residual gas in the cathode ray tube to increase a degree of vacuum in the cathode ray tube, the getter flash is carried out by high-frequency heating the getter in the cathode ray tube to vapor it onto an inner surface of the cathode ray tube.
Then, thermal decomposition of a cathode is performed, and then ageing is carried out to activate the oxide cathode of the electron gun at a point of time when the gas molecules of the residual gas is reduced.
In addition to the above, as the technology for improving the degree of vacuum in the cathode ray tube, in Japanese Patent Unexamined Publication No. Sho. 63-248034, a heater of the electron gun is heated in order to decompose the gas molecules of the residual gas, which still remain in the cathode ray tube, into carbon dioxide and moisture, which the getter film is ready to chemically adsorb. Also, in Japanese Patent Unexamined Publication No. Hei. 5-28907, as shown in
FIG. 11
, as a method of activating the cathode, gun heating in which high-frequency dielectric heating is applied to parts of the electron gun is carried out prior to the ageing step.
In the cathode ray tube manufacturing method in the related art, when the getter is fitted to the funnel, t he getter is oxidized and also adsorbs a quantity of gas because the cathode ray tube is heated in the frit sealing step. Then, because such gas is outgassed at the time of getter flash immediately before the getter is vapored, the gas is readsorbed by materials in the cathode ray tube and then discharged in the ageing step or in operation to exert a harmful influence upon the cathode. As a result, the electron emmitting characteristic of the cathode is lowered. In other words, the emission life characteristic of the cathode ray tube is degraded.
Also, the gas which is discharged before the getter flash is physically adsorbed by inner structures of the cathode ray tube by virtue of the van der Waals force, etc., and such gas cannot be adsorbed by the getter film after the getter flash to still remain in the inner structures of the cathode ray tube. Therefore, the gas which has been physically adsorbed is discharged gradually in the cathode ray tube according to the temperature rise caused in the ageing step or in operation of the cathode ray tube to exert the harmful influence upon the cathode. Thus, the emission life characteristic of the cathode ray tube is also degraded.
In addition, if merely the thermal decomposition of the cathode is carried out by heating an electron gun mounting structure to 200° C. or more after the getter flash, the temperature rise of the inner structures of the cathode ray tube is small and thus the outgas which has been physically adsorbed is small. In particular, since the gas which has been physically adsorbed by an inner coating graphite acting as an internal conductor on an inner surface of the funnel portion cannot be discharged during manufacturing steps of the cathode ray tube, such heating of the electron gun mounting structure can make only a small contribution to improvement of the emission life characteristic.
SUMMARY OF THE INVENTION
The present invention has been made to overcome the above subjects, and it is a first object of the present invention to provide a cathode ray tube manufacturing method which is capable of outgassing a gas, which has been physically adsorbed by inner structures of a cathode ray tube after getter flash, into an inside of the cathode ray tube during manufacturing steps of the cathode ray tube and then causing the getter film to chemically adsorb the gas not to be outgassed into the inside of the cathode ray tube in the ageing step or in operation of the cathode ray tube.
Also, it is a second object of the present invention to provide a cathode ray tube manufacturing system which is capable of discharging the gas, which has been physically adsorbed by the inner structures of the cathode ray tube, into the inside of the cathode ray tube and then causing the getter film to chemically adsorb the gas.
In order to achieve the above first object, according to a first aspect of the invention, there is provided a cathode ray tube manufacturing method comprising: an exhaust step of removing an air and a residual gas in an inside of a cathode ray tube; a getter flash step of removing the residual gas; a heating step for heating a funnel portion of the cathode ray tube; and an ageing step for activating the cathode.
In order to achieve the above second object, according to a second aspect of the invention, there is provided a cathode ray tube manufacturing system comprising: a moving board for moving a cathode ray tube in parallel with a set of surfaces of a funnel portion of the cathode ray tube while fixing the cathode ray tube; infrared seating means arranged in parallel with a carrying direction of the moving board and at a level higher than a lower end of the moving board along the funnel portion of the cathode ray tube; and a supporting table for supporting the moving board and the infrared heating means, wherein the moving board has an auxiliary mirror surface which reflects an infrared ray to the funnel portion in a carrying direction side.
According to a third aspect of the invention, there is provided a cathode ray tube manufacturing system comprising: a moving board for moving a cathode ray tube while fixing the cathode ray tube; infrared heating means arranged in parallel with a carrying direction of the moving board along a funnel portion; and a cage for supporting the infrared heating means to cover the cathode ray tube.
REFERENCES:
patent: 2871086 (1959-01-01), Korner et al.
patent: 5766054 (1998-06-01), Kaihara
patent: 2002/0042240 (2002-04-01), Fujimura et al.
patent: 57067260 (1982-04-01), None
patent: 58-051443 (1983-03-01), None
patent: A63181237 (1988-07-01), None
patent: A63248034 (1988-10-01), None
patent: 5028907 (1993-02-01), None
patent: 1019970008297 (1997-02-01), None
patent: 1019970051680 (1997-07-01), None
Adachi Etsushi
Imanishi Wataru
Nakamura Chikayuki
Sugano Takeshi
Birch Stewart Kolasch & Birch, LLP.
Mitsubishi Denki & Kabushiki Kaisha
Ramsey Kenneth J.
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