公开(公告)号：JP2001110026A

公开(公告)日：2001-04-20

申请号：JP2000250779

申请日：2000-08-22

Applicant: IBM

Inventor： ALEX KURIUINJI ,  JOHN JAMES GUNIWEKU ,  ROBERT ALLEN HUTCHINS ,  STEVEN CARTER WILLS

IPC: G11B5/584 ,  G11B5/55 ,  G11B5/58 ,  G11B21/08

Abstract: PROBLEM TO BE SOLVED: To increase the track density of a data storage medium while using a servo track of a conventional medium in regard to a servo position detector which detects a dividing position that had the offset displacement to the edge of the servo track and follows the dividing position. SOLUTION: The servo tracks 40 and 42 have edges 47 and 48 on both sides opposite to each other of a center recorded servo signal 44, and a prescribed distance is set between both edges 47 and 48. A servo reproduction element includes an active detection area that is not larger than and substantially equal to the said distance set between the edges 47 and 48. An independent position detector detects a rough position of the servo reproduction element and shows one of both edges 47 and 48 or one of dividing positions 55-58 that is aligned with the servo reproduction element. A logic circuit compares two detected servo signals with each other and decides a ratio between both signals. Then an error is decided between the decided ratio of both servo signals and a prescribed ratio.