Patent ID: 6947233
Filing Date: 2005-09-20
Classification: G11B

Abstract:
1. A disk drive apparatus comprising: a plurality of disks each including at least one recording surface on which servo information items each containing position information are recorded, each servo information item containing a servo mark used to identify said each servo information item, the servo information items being recorded at regular intervals on a single circumferential portion of each recording surface of the disks; a head provided for each recording surface of the disks and used at least to read information from a corresponding disk; means for selecting one of the heads; a servo gate generator configured to generate a series of servo gate pulses indicative of timings at which the servo information items are read by a head, selected by the selecting means from the corresponding disk; detection means for starting, in a first mode each time the servo gate generator generates a servo gate pulse, detection of the servo mark, contained in said each servo information item, from information read by the selected head from the corresponding disk, thereby detecting, from the read information, the position information contained in said each servo information item, at a timing determined by a timing at which the servo mark has been detected, the detection means detecting, in a second mode, the servo mark and the position informaton, contained in said each servo information item, from the information read by the selected head from the corresponding disk, at respective timings determined, by timings at which the servo gate generator generates respective servo gate pulses; means for controlling, in the first mode, generation of the servo gate pulses by the servo gate generator, using a program; and a servo-mark-continuity detector configured to detect, in the first mode, that servo marks have been detected continuously, thereby switching the first mode to the second mode.