Multi-Wedge Servo Control Using Servo Head and Sync Head in Hard Disk Drive
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
This article describes a technique to control the multi-wedge servo system in a hard disk drive. The main point is the introduction of the servo surface and what we call "the hard sector sync surface". By this technique four wedge servos, which cut the seek latency for the wedge information by four, can be inserted in one cylinder. The hard sector format to make the servos transparent to the hard disk controller is employed. The hard sector sync surface has a special signal pattern named 'sector 8 mark' that is used to detect the nearest wedge servo information to make positioning correction after seeking. In the conventional method for the wedge servo system, each cylinder has only one wedge servo. To detect it after seeking, the index signal has to be detected, which indicates the beginning of the wedge information.