Electron gun
AssigneeNew Japan Radio Co., Ltd.
InventorsToru Kimura, Misao Iseki, Hideyuki Obata
Life of this patent
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Abstract
An electron gun comprising a cathode having an electron emitting surface and whose planar shape is circular; a heater; an anode being arranged to oppose the cathode; and a heat resistant member. The anode applies a positive potential relative to the cathode to extract electrons in a predetermined direction. The cathode has, in a central portion thereof, a through hole along a central axis of the cathode. The heat resistant member has a first portion to close the through hole and a second portion being positioned between the cathode and the heater.
Claims20
An electron gun comprising a cathode having an electron emitting surface in form of curved concave, whose planar shape is circular and to focus an electron beam;
- a heater;
- and an anode being arranged to oppose the cathode, wherein
- a through hole along a central axis of the cathode is provided in a central portion of the cathode;
- and
- a heat resistant member having a first portion to close the through hole and a second portion being jointed to a bottom surface being a surface opposite to the electron emitting surface of the cathode is arranged in the electron gun;
- and
- the first portion has a projection portion that protrudes from a jointing plane between the second portion and the bottom surface toward the through hole, and a thickness of the projection is not less than one fourth and not more than one tenth of a depth of the through hole.
An electron gun comprising a cathode having an electron emitting surface in form of curved concave, whose planar shape is circular and to focus an electron beam;
- a heater;
- and an anode being arranged to oppose the cathode, wherein
- a through hole along a central axis of the cathode is provided in a central portion of the cathode;
- and
- a heat resistant member having a first portion to close the through hole and a second portion being jointed to a bottom surface being a surface opposite to the electron emitting surface of the cathode is arranged in the electron gun;
- and
- the first portion has a hollow cylindrical portion that protrudes from a jointing plane between the second portion and the bottom surface toward the through hole, and the hollow cylindrical portion is inserted into the through hole.
Dependencies are inferred from the claim text.