High track density head positioning using sector servos

A fast and accurate head positioning system, which can support a high track density disk drive with greater than 2000 TPI, has been achieved using sector servos. This paper describes several newly developed techniques, such as four-phase servo pattern encoding, modified RZ recording and fast and accurate positioning control, which make it possible to introduce the sector servos to high track density systems. With these techniques, an access time as fast as servo surface accessing and ±0.4 μm positioning accuracy have been achieved.