Patent ID: 9653248
Date: 2017-05-16
CPC Classifications: A61B,H01J

Claim:
1. An X-ray tube comprising: an anode target which emits X-rays upon incidence of an electron beam on the anode target; a cathode including a filament and a convergence electrode which includes a groove portion in which the filament is provided, and which causes an electron beam to focus, the electron beam being emitted from the filament toward the anode target through an opening of the groove portion; and an envelope which accommodates the anode target and the cathode, wherein a length direction of the groove portion is a direction along a major axis of the filament, and a width direction of the groove portion is a direction perpendicular to a depth direction and the length direction of the groove portion; the groove portion includes: a pair of first bottom surfaces which are located in the same plane as the filament and between which the filament is interposed in the width direction; and a pair of second bottom surfaces between which the filament and the pair of first bottom surfaces are interposed in the length direction and which are located closer to the opening than the pair of first bottom surfaces, and end portions of the filament are interposed between the pair of second bottom surfaces in the width direction.