Head-Positioning System Employing Ternary-Valued Position Error Signal
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
A head-positioning system for a small hard disk file uses a single servo sector with a ternary-valued position error signal and a stepping mechanism able to step to fractions of a track. An initial approximation of the offset of the real track position from the nominal is made on the basis of a thermal expansion model by assigning values to constants in a model equation. If an access to the track concerned does not produce the null position error signal (PES) value, the head is stepped in the appropriate direction until null is reached. The model constants are updated in accordance with the actual null position so that subsequent accesses should reach the track first time. The steps for computing the necessary constants are as follows.