A disk drive includes a head stack assembly having a storage disk, a data transducer,
an actuator pivot center and a positioner. The positioner includes a magnet assembly,
a primary coil array that generates a first rotational displacement of the data
transducer, and a secondary coil array that generates a second rotational displacement
of the data transducer. The absolute value of the ratio of the first rotational
displacement to the second rotational displacement is at least approximately 1.5:1.
The primary coil array generates a first vibration displacement that causes the
data transducer to move off track, and the secondary coil array generates a second
vibration displacement that is out of phase from the first vibration displacement.
The absolute value of the sum of the first and second vibration displacements is
less than the absolute value of the first vibration displacement. The disk drive
can also include a control system that directs a first current to the primary coil
array and a second current to the secondary coil array that is out of phase from
the first current. The secondary coil array can include a proximal coil and a distal
coil, with the proximal coil being positioned closer to the actuator pivot center
than the distal coil. Further, only a portion of at least one of the coils is positioned
directly between the magnet arrays. In another embodiment, the head stack assembly
includes a latitudinal axis that divides the head stack assembly into a positioner
region and a transducer region. The secondary coil array is positioned substantially
within the positioner region of the head stack assembly. The positioner generates
a primary force and a secondary force that combine to generate a constant net force
in a direction along the longitudinal axis while the data transducer moves between
the inner diameter and the outer diameter.
