X-ray tubes
AssigneeHitachi, Ltd.
InventorsTadashi Hayashi, Setsuo Nomura
Life of this patent
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Abstract
In an X-ray tube comprising a cathode electrode including a filament for emitting electrons and a focusing electrode having a focusing groove adapted to contain the filament, and an anode electrode opposing the cathode electrode and maintained at a high potential which is positive relative to the filament, an electron emitting region of the filament facing the anode electrode is formed as a substantially flat surface, and the filament, the focusing electrode and the anode electrode are arranged such that a portion of the anode electrode upon which electron collide will be positioned in a focal plane of a cathode lens formed by the filament, the focusing electrode and the anode electrode.
Claims5
An X-ray tube for producing a minute focused spot of high current density comprising a cathode electrode including a filament for emitting electrons and a focusing electrode having a focusing groove adapted to contain said filament, and an anode electrode opposing said cathode electrode adapted to be maintained at a high potential which is positive relative to said filament, wherein a relatively large electron emitting region of said filament facing said anode electrode is formed as a substantially flat surface, and wherein said filament is disposed at a predetermined depth of said focusing groove, the depth being determined as relatively small compared to the width of said focusing groove, a portion of said anode electrode upon which electrons collide being positioned in a focal plane of a cathode lens which is formed by said filament, said focusing electrode and said anode electrode, said cathode lens having a weak focusing action with a focal length substantially equal to the distance between said anode electrode and said filament to produce a minute focused spot of high current density.
Dependencies are inferred from the claim text.