Patent ID: 6839194

Claim:
A disk drive apparatus comprising: at least one disk including at least one recording surface on which servo information items are recorded at regular intervals in a direction of a circumference of the at least one disk, the servo information items including respective position information items and respective servo marks used to identify the servo information items; a head provided for the at least one recording surface and used to read information from the at least one disk; a servo detector configured to detect each servo information item from the information read by the head from the at least one disk; a servo mark detector configured to detect a corresponding one of the servo marks from said each servo information item detected by the servo detector; a counter configured to measure a servo interval, the servo interval being an interval between two successive ones of the servo marks detected by the servo mark detector; a correction circuit configured to correct a predetermined time period T 2 on the basis of the servo interval measured by the counter and a predetermined ideal servo interval; a determination circuit configured to determine which one of the time period T 2 and a time period T 2 ′ obtained by correcting the time period T 2 using the correction circuit should be used; and a servo-sector-pulse-generating unit configured to generate a servo sector pulse a predetermined time period T 1 after the servo mark detector detects each servo mark, the time period Ti being shorter than the time period T 2 , the servo-sector-pulse-generating unit generating a pseudo servo sector pulse when the time period determined by the determination circuit has elapsed after detection of said each servo mark, if a next servo mark is not detected during the time period determined by the determination circuit.