X-ray generation tube, X-ray generation device including the X-ray generation tube, and X-ray imaging system
AssigneeCanon Kabushiki Kaisha
InventorsKazuya Tsujino, Kazuyuki Ueda
Life of this patent
Estimating the term…
Abstract
Provided is a high-output X-ray generation tube in which thermal damage to a target is reduced. The X-ray generation tube includes a target, an electron source, and a grid electrode having multiple electron passage apertures disposed between the target and the electron source. A source-side electron beam on the electron source side with respect to the grid electrode has a current density distribution, and the grid electrode has an aperture ratio distribution so that a region of the source-side electron beam in which a current density is largest is aligned with a region of the grid electrode in which an aperture ratio is smallest.
Claims25
An X-ray generation tube comprising:
- a target for generating an X-ray through irradiation with an electron beam;
- an electron source provided opposed to the target;
- and
- a grid electrode having multiple electron passage apertures,
- wherein the grid electrode is disposed between the target and the electron source so that a part of a source-side electron beam emitted from the electron source passes through the multiple electron passage apertures and irradiates the target,
- wherein the source-side electron beam shows a current density distribution,
- wherein the grid electrode has an aperture ratio distribution,
- wherein a region of the source-side electron beam, in which a current density is largest, is aligned with a region of the grid electrode, in which an aperture ratio is smallest,
- wherein the grid electrode causes the part of the source-side electron beam to pass through the multiple electron passage apertures so as to form a target-side electron beam on the target side of the grid electrode, and
- wherein a current density at a beam center of the target-side electron beam is lower than a current density at a beam center of the source-side electron beam.
An X-ray generation tube comprising:
- a target for generating an X-ray through irradiation with an electron beam;
- an electron source provided opposed to the target;
- a grid electrode having multiple electron passage apertures;
- and
- a focusing lens electrode,
- wherein the grid electrode is disposed between the target and the electron source so that a part of a source-side electron beam emitted from the electron source passes through the multiple electron passage apertures and irradiates the target,
- wherein the source-side electron beam shows a current density distribution,
- wherein the grid electrode has an aperture ratio distribution,
- wherein a region of the source-side electron beam, in which a current density is largest, is aligned with a region of the grid electrode, in which an aperture ratio is smallest,
- wherein the focusing lens electrode focuses the source-side electron beam,
- wherein the focusing lens electrode defines, between the focusing lens electrode and the target, a crossover that is a virtual point at which a beam diameter of the target-side electron beam becomes smallest,
- wherein the focusing lens electrode further defines a crossover conjugate point at a position conjugate to the crossover,
- wherein the focusing lens electrode further defines, on the electron source side, a focus center conjugate point at a position conjugate to a focus center on the target, and
- wherein the grid electrode is disposed at a position from the crossover conjugate point to the focus center conjugate point.
Dependencies are inferred from the claim text.