Dual-Stage Nanopositioning Scheme for 10 Tbit/in Hard Disk Drives With a Shear-Mode Piezoelectric Single-Crystal Microactuator

A dual-stage piezoelectric shear-mode actuation scheme aiming at high-density hard disk drive applications is designed, simulated, and experimentally evaluated. In this actuation scheme, a shear-mode piezoelectric single-crystal microactuator is installed between a suspension and a slider for realizing magnetic head nanopositioning in hard disk drives. The piezoelectric single-crystal-based shear-mode microactuator is dedicatedly designed and made of (1-x)Pb(Zn_1/3Nb_2/3)O₃PbTiO₃ (x=0.06-0.07) material to meet the technical specifications of servo control for 10 Tbit/in² hard disk drives. The shear displacement of this microactuator under a constant voltage is independent of the dimensions of the microactuator, which has the great promise for further miniaturization and excellent performance consistency control. Theoretical analysis shows that the first intrinsic resonance of the microactuator is around 143 kHz. The shear-mode microactuator has a displacement of 25.4-30.7 nm at 12 V at frequencies up to 60 kHz. After it is installed between a suspension and a slider, and tested on a spin stand, the shear-mode microactuator exhibits a working frequency of 39.1 kHz and a displacement of more than 22 nm at 12 V under the disk flying condition. The technical feature and performance as achieved show that the dual-stage nanopositioning scheme using a shear-mode piezoelectric single-crystal microactuator is promising to meet the requirements of servo control for 10 Tbit/in² hard disk drives.