Design Modification of Micro-Actuator to Improve Shock Resistance of HDD

To realize higher track density of a hard disk drive, increasing servo bandwidth may reduce track-misregistration (TMR). However, the servo bandwidth is limited by the mechanical resonances of the arm, coil of the voice coil motor (VCM) and ball bearing pivot. One approach to overcome the problem is using dual stage actuator system. The dual stage actuator (DSA) consists of an primary actuator driven by VCM and a secondary actuator driven by PZT. VCM actuator is used for coarse control of seek and settling whereas the 2^nd actuator is used for fine control of track following. As VCM is turned off during track following in DSA, the VCM resonance does not limit the increase of servo bandwidth any longer. Among the 2^nd actuators, the so-called micro actuator locating at the tip of the suspension and driving head slider is advantageous for higher servo bandwidth and collocation of the 2^nd actuator and the read/write sensor, whereas it is disadvantageous for shock resistance due to large tip mass. In this study, micro actuator is modified in order to improve shock resistance with simple design parametric study.