Patent ID: 7801278
Filing Date: 2010-09-21
Classification: H01J

Abstract:
1. A rotary anode X-ray tube having a center axis, comprising: a cathode for emitting an electron beam; a rotary anode formed into a hollow disk-like shape, which is provided with a target on which the electron beam is irradiated to generate an X-ray, the rotary anode having a disk-like inner surface; a rotating body formed into a hollow cylindrical shape, which supports the rotary anode and has a cylindrical inner surface; a fixed shaft having fixed at both end portions, which is so arranged as to be inserted into the rotating body and to rotatably support the rotating body, the fixed shaft having a disk portion and columnar bearing parts integrally formed with the disk portion and extending along the center axis from the disk portion, the columnar bearing parts having outer surfaces facing the cylindrical inner surface with a first gap, the disk portion having a outer surface opposed to the disk-like inner surface with a second gap communicating with the first gap, wherein the fixed shaft is so formed into a hollow structure as to have a flow path in which a cooling medium to be supplied along the center axis; a lubricant which is applied to the first and second gaps; and first and second dynamic pressure bearings each of which is formed on the outer surfaces of the bearing parts, which includes bearing grooves formed on at least one of the cylindrical inner surface and the outer surfaces of the bearing parts and the lubricant in the first gap, wherein a center of gravity of the rotary anode is arranged between the first and second dynamic pressure bearings.