| 摘要 |
PURPOSE:To detect accurately the off-track quantity without affected by fluctuation in reproduced output level caused by conditons of contact of the magnetic head and the irregularity of magnetic body of a recording medium by detecting th quantity of off-track from the ratio of amplitude between reproduced waveform amplitudes of a pair of servo signals. CONSTITUTION:Reproduced outputs of a magnetic head 9 are amplified by a head amplifer 10, and a timing generator 12 controls detecton timing of amplitude of reproduced signal waveform by a peak hold circuit 13 and sample and hold circuits 14, 15 based on a synchronizing signal (e) obtained in a synchronizing signal detecting circuit 11. The reproduced waveform amplitude of a pair of servo signals that increases and decreases reciprocally in proportion to tracking errors of the magnetic head 9 is obtained. A ratio of reproduced waveform amplitudes is determined by a division circuit 16 and converted to the quantity of off-track by a correcting circuit 17. A stepping motor 19 is controlled through a motor controlling circuit 18, and correction of the position of the mangetic head 9 is performed. |
