Arm Design to Reduce Arm Bending Resonance-Induced Off-Track in a Hard Disk Drive

The paper presents a strategy to reduce the position error signal (PES) induced by arm bending mode in high track density magnetic disk drives. As the track width becomes narrower to increase data storage capacity, off-track due to arm bending mode as well as disk vibration makes a large contribution to track misregistration (TMR). Consequently it is important to reduce arm bending resonance-induced off-track in order to meet TMR budget. A special arm is designed so that head can move back on track to cancel off-track due to asymmetric motion while arm is bending. It is shown that such an arm can reduce TMR due to arm bending mode by allowing the head to move in such a way that will compensate the off-track caused by arm bending mode. Finally, the efficacy of the proposed strategy is verified by measuring PES of actual sample drives with newly designed arm.