Patent ID: 11037590

Abstract:
An approach to a reduced-head hard disk drive (HDD) involves an actuator elevator subsystem that includes a ball screw cam assembly with a hybrid permanent magnet (PM)-variable reluctance (VR) stepper motor disposed therein, to rotate the cam screw, which vertically translates an actuator arm assembly so that a corresponding pair of read-write heads can access different magnetic-recording disks of a multiple-disk stack. A suitably configured hybrid stepper motor can provide 200 full steps/rev for a 3.8 mm translation. Thus, to meet or surpass a step resolution of 6 μm/μstep or 0.5625°/μstep, the hybrid stepper motor would only need to be operated at 4 micro-step mode in order to achieve a 0.45°/μstep or 0.00475 mm/μstep, which enables a smoother motion since the available holding torque at the 4th micro-step provides sufficient torque margin to overcome load torque, frictional torque, and detent torque.