Patent Number: 6,166,871

Title: Method for decoding head position signal including on-the-fly compensation for misread track number

Abstract: A method for generating a reliable head position signal including track number validation. A head position signal is generated using two triangular signals PosN and PosQ having a phase difference of a 1/4 period, and a track number which is recorded on the medium. The track number is validated by comparing the relationship of the signs of the signals PosN, PosQ with the track number according to a predetermined rule. The track number may be a corrected if the track number was misread. Subsequently, a position signal generator demodulates the position signal on the basis of the absolute values of signals PosN, PosQ, the signs of the signals PosN, PosQ, and the track number. The accuracy of the head position signal is further improved using a conversion coefficient (position sensitivity factor) for correcting the amplitudes of the signals PosN and PosQ. A position sensitivity determining portion generates a sum signal (PosN+PosQ) and/or a difference signal (PosN-PosQ) and positions a head at a point of a track at which the absolute values of the signals PosN, PosQ are equal by using either of the sum signal and the difference signal. The position sensitivity determining portion then measures the sum signal .vertline.PosN.vertline.+.vertline.PosQ.vertline. of the absolute values of signals PosN, PosQ , and determines the position sensitivity factor so that the measured value is equal to a preset value.

Inventors: Takaishi; Kazuhiko (Kawasaki, JP)

Assignee: Fujitsu Limited

International Classification: G11B 27/30 (20060101); G11B 21/10 (20060101); G11B 27/10 (20060101); G11B 5/55 (20060101); G11B 5/596 (20060101); G11B 005/09 ()

Expiration Date: 12/26/2017