Electric lamp and discharge devices – Electrode and shield structures – Cathodes containing and/or coated with electron emissive...
Patent
1997-12-09
2000-03-07
Patel, Vip
Electric lamp and discharge devices
Electrode and shield structures
Cathodes containing and/or coated with electron emissive...
313346DC, H01J 128, H01J 114
Patent
active
060344695
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electron tube such as a color picture tube, a klystron tube, a traveling wave tube, a gyrotron tube.
BACKGROUND ART
In recent years, a micro-wave electron tube such as a klystron or the like have had a tendency to exhibit a high output. Particularly, those tubes which are used in a plasma apparatus for nuclear fusion or a particle accelerator exhibit an output of a megawatt or more. A much higher output is required for those tubes. Meanwhile, there have been demands for developments in a color picture tube improved in resolution by increasing scanning lines and a super high frequency responsive picture tube, and hence, improvements in brightness have been required. Improvements in brightness have also been required for a projection tube. To respond to these requirements and demands, the emission current density of a current from a cathode must be greatly increased in comparison with a conventional apparatus.
Several conventional electronic tubes such as a color picture tube used in a color picture receiver require a high voltage supplied to a convergence electrode, a focus electrode or the like, in addition to an anode voltage. In this case, a problem issues in the aspect of a withstand voltage if a high voltage is supplied from a stem portion of the color picture tube. Therefore, a method is adopted in which a resister for a divisional voltage together with an electron gun are incorporated as a electron-gun built-in resister into the color picture tube and in which an anode voltage is divided to supply high voltages to electrodes, respectively.
Starting from studies made in 1939, developments have been made to use this tube as an amplifier tube, an oscillation tube, or the like which can widely response to an UHF band to a milli wave range. In 1960s, further developments have been started to use a klystron tube for a satellite communication earth station. In 1970s, studies have been promoted in view of high efficiency operation of a klystron tube, and products with an efficiency of 50% or more have been put into practical use including UHF-TV broadcasting. Recently, a klystron tube of a super high power has been developed which attains an efficiency of 50 to 70%, a continuous wave output of 1 MW, and a pulse output of 150 MW, and has been used in an accelerator of a super large scale, a plasma heating apparatus for nuclear fusion studies. A klystron tube can generate a high power at a high efficiency, and is therefore used widely in the field of high power tubes.
A traveling wave tube was invented in 1943 and was completed thereafter. There are various types of traveling wave tubes, such as a spiral type, a cavity coupling type, a cross finger type, a ladder type, and the likes. A traveling wave tube of a spiral type has been widely used as a transmitting tube to be mounted on an air-plane, an artificial satellite or the like. A cavity connection type traveling wave tube has been developed for the purpose of compensating for a withstanding power capacitance of a spiral type, and has been put into practice mainly as a transmitting tube for a satellite communication earth station. Although a traveling wave tube normally attains an efficiency of about several to 20%, a traveling wave tube which attains an efficiency of 50% has been developed for a satellite when electrical potential depression-type corrector is provided with the traveling wave tube.
Meanwhile, as well-known, a gyrotron tube is an electron tube based on an operation principle of a cyclone maser effect, and is used as a high frequency high power source which generates a high power milli wave of several tens to several hundreds GHz.
An impregnated-type cathode ensures a higher emission current density than an oxide cathode, and has therefore been used as an electron tube for a cathode ray tube, a traveling wave tube, a klystron tube, a gyrotron tube, or the like. Use of an impregnated-type cathode has been limited to particular applications such as an HD-TV tube, an ED-TV tube, and the lik
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Patent Abstracts of Japan, No. 59-203343, Nov. 17, 1984, Appln. No. 58-077432, May 1983, Yamamoto Yoshihiko "Impregnated Cathode".
Higuchi Toshiharu
Homma Katsuhisa
Kobayashi Kazuo
Koyama Kiyomi
Matsumoto Sadao
Gerike Matthew J.
Kabushiki Kaisha Toshiba
Patel Vip
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