Patent ID: 8223455

Claim:
A rotor hub for use in a motor of a disk drive, comprising: a shaft connecting portion arranged to be directly connected to a shaft serving as a central axis such that the rotor hub rotates together with the shaft; a disk loading portion centered about the central axis, arranged radially outside the shaft connecting portion so as to surround the central axis; a hollow, approximately cylindrical yoke arranged below the disk loading portion, centered about the central axis, and supporting a field magnet at one of an inner side surface thereof and an outer side surface thereof; and a flexible portion connecting the disk loading portion to the yoke and arranged to absorb a force applied thereto from the yoke; wherein an upper portion of the yoke is positioned below the flexible portion; the yoke protrudes in a downward direction such that a radial outer surface of the yoke does not contact any portion of the flexible portion; the disk loading portion includes an upper surface arranged to receive a disk-shaped storage medium thereon and a lower surface including a concave portion, the concave portion opening toward the lower surface and having an approximately annular shape centered about the central axis; an axially uppermost portion of the flexible portion is arranged at the same axial height as an axially uppermost portion of the concave portion; and a radially outer surface of the concave portion is a radially inner surface of the flexible portion.