Transducer Positioning System and Data Disk Therefor

This U.S. Patent (4,390,912) describes a transducer positioning system and a magnetic disk designed for a disk drive unit. The system features a magnetic disk with interleaved data and servo sectors. Each servo sector contains at least two sets of circumferentially spaced servo information blocks, which include first and second asymmetrical, time-displaced, complementary signals. These signals are recorded in radially adjacent blocks, and their phase boundaries define the centerlines of the data tracks. The system includes a servo controller that uses a null detector to position a movable transducer over a data track centerline based on these phase boundaries. Additionally, the controller uses a track difference counter to count zero crossings during transducer movement, providing accurate positioning and velocity control during track seeking operations.