Patent Number: 7,612,961

Title: Magnetic recording disk and disk drive with patterned phase-type servo fields for read/write head positioning

Abstract: A magnetic recording disk drive uses a disk having pre-patterned servo sectors extending generally radially across the data tracks. The servo sectors include at least two position error signal (PES) bursts or fields. The phases of the PES fields in the servo readback signal are demodulated to generate a PES to control the disk drive actuator for positioning the read/write heads. Each field contains generally radially directed magnetized stripes, with each stripe comprising a plurality of discrete radially-spaced generally parallelogram-shaped islands, each island having its length oriented at an acute angle relative to a track centerline. The stripes have alternating polarity of magnetizations in the along-the-track direction. In one implementation there are four fields: a first pair of fields A and B wherein the pattern of the radial stripes in field A is the mirror image about a radial line of the pattern of the radial stripes in field B, and a second like pair of fields C and D, but wherein the radial stripes in fields C and D are shifted radially from the radial stripes in fields A and B.

Inventors: Yamamoto; Satoshi (San Jose, CA)

Assignee: Hitachi Global Storage Technologies Netherlands B.V.

International Classification: G11B 5/09 (20060101)

Expiration Date: 1/03/02017