Improved head gimbal assemblies reducing TMR (Track Mis-Registration) in
a hard disk drive are provided. These head gimbal assemblies are as mechanically
simple as contemporary head gimbal assemblies, support parallel flying sliders
over flat disk surfaces, and reduce TMR' induced by disk vibration. They are easier
to build, more reliable, and cost less to make, than other known approaches at
comparable track densities and rotational rates. The improved head gimbal assemblies
include three sets of mechanisms moving the slider parallel the disk surface, when
the disk surface is flat, and radially moving the slider toward the track, when
the disk surface is bent. The first and third mechanisms as well as the second
and third mechanisms can be used together in a head gimbal assembly.
An improved and distinctive servo-controller scheme resulting in an overall improvement
in PES performance, particularly when applied to hard disk drives employing the
invention's TMR reduction mechanisms. The servo-controllers trade off gain in the
disk vibration frequency range, in favor of, increased rejection of low frequency
disturbances. This leads to the lowest PES statistics, when applied to hard disk
drives with the TMR reduction mechanisms of the invention.
