In-pivot hybrid stepper motor for ball screw cam elevator mechanism for reduced-head hard disk drive

A permanent magnet (PM)-variable reluctance (VR) hybrid stepper motor configured to rotate about a fixed shaft, the hybrid stepper motor comprising:

• a plurality of ring-shaped permanent magnets (PMs);
• a stack of electrical steel lamination rings interposed between each adjacent pair of the PMs;
• wherein the PMs and the lamination rings collectively operate as a rotor of the hybrid stepper motor;
• a stator, disposed within the rotor, comprising a stack of electrical steel laminations configured with a plurality of main poles each having a plurality of teeth;
• and
• a coil wound on each of the main poles.

A method for vertically translating a head-stack assembly (HSA) in a hard disk drive (HDD) to access multiple magnetic-recording disks, the method comprising:

• driving a permanent magnet (PM)-variable reluctance (VR) hybrid stepper motor disposed within a ball screw cam assembly comprising a screw, thereby rotating the screw about a coaxial fixed shaft;
• allowing a planar multi-ball bearing assembly that is coupled with the HSA to translate vertically in response to rotating the screw;
• and
• while the bearing assembly is translating, sensing the vertical position of the HSA.

A reduced-head hard disk drive (HDD), comprising:

• recording means for storing digital information;
• reading/writing means for reading from and writing to the recording means;
• means for moving the reading/writing means to access portions of the recording means;
• a permanent magnet (PM)-variable reluctance (VR) hybrid stepper motor rotating means for rotating cam means about a fixed shaft for translating the reading/writing means from one recording means to another recording means;
• and
• means for sensing a vertical position of the reading/writing means.