| 摘要 |
PURPOSE:To correct the error of a servo signal from an ideal value, which is caused by a defect on a magnetic disc, to allow a magnetic head to follow up tracks with a high precision, by offsetting the magnetic head on a basis of the corrected servo signal to allow the magnetic head to follow up data tracks with a high precision. CONSTITUTION:An original servo signal 9 is inputted to a rotation position detecting circuit 20, and an ROM22 is accessed by an address 21 and a cylinder number 19 which are obtained by detecting a rotation position of a servo track, and correcting data (digital data) 23 is generated. Correcting data 23 is converted to a correcting voltage 25 by a D/A converter 24 and is applied to a position signal generating circuit 12. Since a servo signal 11 including position deviation is inputted to the position signal generating circuit 12 also, the correcting voltage 25 cancels an unnecessary position deviation in the servo signal 11, and a position signal 13 is obtained which controls a voice coil motor 17 so that the locus which a data head 6 describes for a magnetic disc 2 is a perfect circle. |
