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 for 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.