| 摘要 |
PURPOSE:To equalize the density of both the data track and the servo-track, and also obtain a position signal which can be converted to an exact speed signal, by leading out a prescribed position signal in accordance with two-phase servo-information from the servo-head. CONSTITUTION:The servo-information detection part 60 generates signals A-D which are periodically varied in accordance with the position of the servo-head 20, generates position signals E-H which are out of phase by 90 deg. each in accordance with said signals A-D, and sends them out to the selective part 70. In case when a level of the signal E is within a prescribed range, the selective part 70 selects and outputs one of the signals E, G in accordance with the polarity of the signal F or H, and also, in case a level of the signal E is not within the prescribed range, the selective part 70 selects and outputs one of the signals F, H in accordance with the polarity of the signal E or G. And, the head 20 is located in the radial direction of the disk so that a level of this output position signal P becomes zero. |
