VCM design to improve dynamic performance of actuator in a disk drive

PES design margin of current hard disk drive becomes getting smaller as track density of high-capacity disk drives increases. In the present work, a new actuator design concept is introduced for reducing one of the actuator vibration modes so called a butterfly mode that normally limits expansion of servo bandwidth. The new actuator has single coil with four sections having respective particular directions. By adjusting the length and direction of the sections of the VCM coil, the forces perpendicular to track seeking direction can be balanced with each other, and then the butterfly mode is not excited by the resultant force of VCM. Contribution of the proposed actuator design for the PES management is verified by numerical simulations. As a result, the servo bandwidth is to be increased so that PES can be decreased due to improved dynamics of the proposed method.