Tracking Dynamics of In-line Suspensions in High-Performance Rigid Disk Drives with Rotary Actuators

Abstract

The laser Doppler interferometric modal measurement technique is combined with finite element analysis to study the dynamics of in-line suspensions under actual operating conditions in commercially available small form factor rigid disk drives equipped with rotary actuators. It is shown that the sway mode, which is a result of in-plane bending of the load beam, is the primary source of radial slider motions and contributes significantly to off-track error. It is also shown that the initial deformed geometry of the suspension, which is determined by the boundary condition during large angle deflection and the nature of the pre-bend shape, has direct effects on the in-plane stiffness of the suspension and therefore the sway mode frequency.