Head position control on quasi-static read/write tester

To develop high-density magnetic recording systems, a simple feedback system without servo writing was applied to a quasi-static read/write tester in which a medium reciprocates against a stand-still head. The head position signal in cross-track direction during the scanning is fed back to the high-precision piezoelectric actuator of the media stage. The stage is controlled so as to make the head/medium alignment error zero. A contact head slider assembled on a parallel-link suspension was used to evaluate the feedback system. The tester shows an accuracy of 1.5 nm in cross-track direction which is preferable for the read/write tests at future high recording densities.