Development of a single coil coupled force VCM actuator for high TPI magnetic recording

A novel high bandwidth actuator assembly (HBX4) is developed for the applications of high TPI recording in hard disk drives. The novel design in voice coil motor (VCM) construction, with flat moving-coil, is as simple as a conventional one. The VCM generates orthogonal force or pure torque. A 3D finite element analysis (FEA) is conducted in the electromagnetic design to optimize some critical electromagnetic parameters and the main dimensions. A 3D FEA is also carried out to predict the dynamic performance. The study shows that the lateral quasirigid body vibration mode (QR mode), which limits the servo bandwidth in a conventional actuator, has been substantially suppressed. Measurement of the characteristics of a prototype is carried out and the result is discussed.