| 摘要 |
<p>A system for detecting a head position for use in a tracking servo system to accurately and quickly place a read-write head (31,32) on a selected data track of a magnetic disk memory (30). The magnetic disk comprises data sectors and servo sectors embedded between the data sectors. A two-phase servo information pattern of a 4-track period is recorded on each of the servo sectors. Servo information (A, B, C, D) is reproduced by the read-write head from the each servo sector to produce two-phase first and second position signals (X, Y) which vary like a substantially trapezoidal waveform as a function of head position. A track on which the head is present among the tracks within one period of the servo information pattern is detected dependent on the polarity relation between the first and second position signals. Third and fourth positions signals (U, V) are formed which respectively correspond to the sum of and the difference between the first and second position signals (X, Y). The present positions of the head within the detected track is accurately obtained in accordance with either one of the third and fourth positions signals (U, V) which varies linearly in the detected track. A head actuator (33) is controlled in accordance with a distance between the present position of the head (31, 32) and the selected track, so that the head is accurately and quickly positioned in the target track.</p> |
