Patent ID: 8553345
Filing Date: 2013-10-08
Classification: G11B

Abstract:
1. A position demodulation apparatus comprising: a demodulator configured to demodulate a first demodulation signal and a second demodulation signal having a phase difference of 90 degrees to the first demodulation signal based on a read-out signal obtained by reading out a servo pattern recorded on a medium by the head for positioning of a head with respect to the medium; a correcting module configured to perform on the first demodulation signal and the second demodulation signal a correction in which, when a trace of a Lissajous figure is drawn representing the first demodulation signal and the second demodulation signal as values on coordinate axes different from each other on a plane, a ratio of respective lengths between intersections of the trace intersecting with two axes orthogonal at an origin of the plane and different from the coordinate axes is kept constant; and a position demodulator configured to demodulate a positional signal for determining a position of the head based on the first demodulation signal and the second demodulation signal after being corrected by the correcting module.