| 摘要 |
PURPOSE:To eliminate decrease of recordable data signals by record of servo signals by detecting positioning error of a magnetic head once every rotation of a magnetic disk and making closed loop servo. CONSTITUTION:One index pulse 21 is generated in every rotation of a magnetic disk, and a servo signal consisting of burst signals A, B is recorded alternately deviating by 1/2 track pitch from data recording tracks n, n+1-. When a magnetic head 11 that reproduces track n+1 deviated upward, regenerative amplitude of the signal A decreases, and regenerative amplitude of the signal B increases. On the other hand, reproducing output is inputted from the magnetic heard 11 to a positional deviation detecting circuit 13. Direction and amount of positional deviation of the head 11 is detected by finding difference of amplitude of burst signals A, B, and fed back to a step motor 7 through a comparator 17, an amplifier 18 and a driving circuit 19. It is enough to record the servo signal at one place in every recording track at specified part in circumferential direction of the magnetic disk. |
