| 摘要 |
PURPOSE:To attain accurate positioning of a head to an object track by narrowering a track pitch of servo information forming a track deflection detecting region in advance to obtain track deflection information of a disc recording medium with high accuracy. CONSTITUTION:The 2nd servo track ST2 comprising the 2nd track pitch T2 having 1/2 width of the 1st track pitch T1 is formed to the 2nd servo sector 17. Servo information is written to the servo track ST2. Since the 2nd track pitch T2 of a track deflection detecting region 13 is narrower than the effective recording reproducing track width T1 of the head, a linear region of a position signal obtained from servo information taking at least four tracks as one period has the 2nd track pitch or over without fail. Thus, a complete linear signal consecutive in the track broadwise direction is obtained by applying prescribed operation to at least two position signals different from the phase by one track's share on the 2nd track pitch T2. |
