A dual-stage magnetic disk drive actuator using a piezoelectric device for a high track density

A dual-stage actuator has been developed using a piezoelectric device for a magnetic disk drive with a high track density over 15 kTPI. This actuator uses a VCM (voice coil motor) rotary actuator as a coarse actuator and a piezoelectric actuator installed in a head-arm as a fine actuator. The stroke of the fine actuator is 4.6 μm, which is sufficient for a track pitch of 1.5 μm at 17 kTPI. The head position is detected by an optical method using a dot-pattern etched on a disk. The authors describe the design of the dual-stage actuator, including structural analysis, its static and dynamic characteristics, the dual-stage feedback control system. Experimental results of tracking with high accuracy on a 3.5-in disk-drive unit are presented