Advance piezo-actuator technologies for hard disk drive applications

Piezoelectric actuators have been widely used in hard disk drives to form dual stage actuations for position control. Early designs, categorized as milli-actuators, typically place piezo elements on suspension base plate to swing suspension to induce motion of the head, located at the suspension tip. In recent years, micro-actuators with piezo elements next to the magnetic heads are introduced to improve positioning accuracy. These micro-actuators are first reviewed in this paper. An analytic model is then derived to understand key design parameters related to the micro-actuator performance and to compare designs. With the guidance of the model, the paper explores improvement directions for future micro-actuators. Combining the milli-actuator and micro-actuator to form triple stage actuations is shown to not only provide better position control accuracy than the dual stage actuations, but also expand micro-actuator design space for further performance enhancement, which provides a path for hard disk drive industry to keep growing track density for higher storage capacity.