Storage apparatus, storage control circuit, and head-position-displacement measuring method
A measurement recording unit causes the head to move across a predetermined amount, at least more than one track during one lap of track, with a predetermined radial position and a track position of the magnetic disk being taken as recording start points, thereby writing measurement data while drawing a spiral path. A measurement reading unit causes the measurement data recorded in a spiral manner to be read while gradually shifting a read-beginning point within a predetermined scanning range from an inner perimeter side including the recording start points to an outer perimeter side. A position-displacement detecting unit finds a distribution of amplitudes of a read-back signal within a read scanning range and detects, in a distribution of evaluation values, an amount of position displacement of a read head and a write head on the storage medium in a radial direction for storage.
1. A storage apparatus comprising:
a storage medium with a configuration of having a plurality of tracks formed of a magnetic-storable magnetic substance, the tracks being sectioned by a non-magnetic substance that does not allow magnetic recording;
a head having a read head for reading magnetic storage information recorded on the tracks and a write head for writing magnetic storage information on the tracks;
a measurement data recording unit that causes the head to move across a predetermined amount at least equal to or more than one track during one lap of track, with a predetermined radial position and a track position of the storage medium being taken as a recoding start point, thereby writing measurement data in the storage medium while drawing a spiral path;
a measurement data reading unit that causes the head to move, while scanning read-beginning points within a predetermined scanning range from an inner perimeter side including the recording start point of the measurement data recording unit to an outer perimeter side, across the predetermined amount of the measurement data recording unit for each of the read-beginning points, thereby reading the measurement data from the storage medium while drawing a spiral path; and
a head-position-displacement detecting unit that finds a distribution of evaluation values within the predetermined scanning range from a measurement data read-back signal obtained by the measurement data reading unit and detects, in the distribution of evaluation values, an amount of position displacement of the read head and the write head on the storage medium in a radial direction for storage.
2. The storage apparatus according to claim 1 , wherein
the measurement data recording unit previously sets a target shift amount obtained by dividing a track width by the number of servo sectors for recording in a track perimeter direction at predetermined spacing and, after starting writing from the recording start point, causes the magnetic head to move in a radial direction by the target shift amount upon each servo-sector detection, thereby writing the measurement data in the storage medium while causing the magnetic head to move across at least one track during one lap of track.
3. The storage apparatus according to claim 2 , wherein
the measurement data reading unit causes, after starting reading from a read-beginning point from which scanning is performed within the predetermined scanning range, the magnetic head to move in the radial direction by the target shift amount upon each servo-sector detection, thereby reading the measurement data from the storage medium while causing the magnetic head to move across at least one track during one lap of track.
4. The storage apparatus according to claim 1 , wherein
the head position displacement detecting unit detects amplitudes of a read-back signal obtained from the measurement data reading unit as the evaluation values, and detects the amount of position displacement from a peak value in a distribution of the amplitudes.
5. The storage apparatus according to claim 4 , wherein
the head-position-displacement detecting unit detects, as the amplitudes of the read-back signal, an average value or an accumulated value of the amplitudes of the read-back signal obtained by reading one spiral path.
6. The storage apparatus according to claim 1 , wherein
the head-position-displacement detecting unit detects error rates of a read-back signal obtained by the measurement data reading unit as the evaluation values, and detects the amount of position displacement from a bottom peak value in the distribution of the error rates.
7. The storage apparatus according to claim 1 , wherein
the amount of position displacement is detected and stored for each of all track positions of the storage medium by the measurement data recording unit, the measurement data reading unit, and the head-position-displacement detecting unit.
8. The storage apparatus according to claim 1 , wherein
the amount of position displacement is detected and stored at a plurality of measurement positions on the storage medium in a radial direction by the measurement data recording unit, the measurement data reading unit, and the head-position-displacement detecting unit, and an amount of position displacement at each position other than the measurement positions is found through an interpolating calculation from amounts of position displacement at measurement positions on both sides.
9. A storage control circuit of a storage apparatus provided with
a storage medium with a configuration of having a plurality of tracks formed of a magnetic-storable magnetic substance, the tracks being sectioned by a non-magnetic substance that does not allow magnetic recording, and
a head having a read head for reading magnetic storage information recorded on the tracks and a write head for writing magnetic storage information on the tracks, the storage control circuit comprising:
a measurement data recording unit that causes the magnetic head to move across a predetermined amount at least more than one track during one lap of track, with a predetermined radial position and a track position of the storage medium being taken as a recoding start point, thereby writing measurement data in the storage medium while drawing a spiral path;
a measurement data reading unit that causes the head to move, while scanning read-beginning points within a predetermined scanning range from an inner perimeter side including the recording start points of the measurement data recording unit to an outer perimeter side, across the predetermined amount of the measurement data recording unit for each of the read-beginning points, thereby reading the measurement data from the storage medium while drawing a spiral path; and
a head-position-displacement detecting unit that finds a distribution of evaluation values within the predetermined scanning range from a measurement data read-back signal obtained by the measurement data reading unit and detects, in the distribution of evaluation values, an amount of position displacement of the read head and the write head on the storage medium in a radial direction for storage.
10. The storage control circuit according to claim 9 , wherein
the measurement data recording unit previously sets a target shift amount obtained by dividing a track width by the number of servo sectors for recording in a track perimeter direction at predetermined spacing and, after starting writing from the recording start point, causes the magnetic head to move in a radial direction by the target shift amount upon each servo-sector detection, thereby writing the measurement data in the storage medium while causing the magnetic head to move across at least one track during one lap of track.
11. The storage control circuit according to claim 10 , wherein
the measurement data reading unit causes, after starting reading from a read-beginning point from which scanning is performed within the predetermined scanning range, the magnetic head to move in the radial direction by the target shift amount upon each servo-sector detection, thereby reading the measurement data from the storage medium while causing the magnetic head to move across at least one track during one lap of track.
12. The storage control circuit according to claim 9 , wherein
the head position displacement detecting unit detects amplitudes of a read-back signal obtained from the measurement data reading unit as the evaluation values, and detects the amount of position displacement from a peak value in a distribution of the amplitudes.
13. The storage control circuit according to claim 12 , wherein
the head-position-displacement detecting unit detects, as the amplitudes of the read-back signal, an average value or an accumulated value of the amplitudes of the read-back signal obtained by reading one spiral path.
14. The storage control circuit according to claim 9 , wherein
the head-position-displacement detecting unit detects error rates of a read-back signal obtained by the measurement data reading unit as the evaluation values, and detects the amount of position displacement from a bottom peak value in the distribution of the error rates.
15. The storage control circuit according to claim 9 , wherein
the amount of position displacement is detected and stored for each of all track positions of the storage medium by the measurement data recording unit, the measurement data reading unit, and the head-position-displacement detecting unit.
16. The storage control circuit according to claim 9 , wherein
the amount of position displacement is detected and stored at a plurality of measurement positions on the storage medium in a radial direction by the measurement data recording unit, the measurement data reading unit, and the head-position-displacement detecting unit, and an amount of position displacement at each position other than the measurement positions is found through an interpolating calculation from amounts of position displacement at measurement positions on both sides.
17. A head-position-displacement measuring method of a storage apparatus provided with
a storage medium with a configuration of having a plurality of tracks formed of a magnetic-storable magnetic substance, the tracks being sectioned by a non-magnetic substance that does not allow magnetic recording, and
a head having a read head for reading magnetic storage information recorded on the tracks and a write head for writing magnetic storage information on the tracks, the method comprising:
a measurement data recording step of causing the head to move across a predetermined amount at least equal to or more than one track during one lap of track, with a predetermined radial position and a track position of the storage medium being taken as a recoding start point, thereby writing measurement data in the storage medium while drawing a spiral path;
a measurement data reading step of causing the head to move, while scanning read-beginning points within a predetermined scanning range from an inner perimeter side including the recording start point in the measurement data recording step to an outer perimeter side, across the predetermined amount in the measurement data recording step for each of the read-beginning points, thereby reading the measurement data from the storage medium while drawing a spiral path; and
a head-position-displacement detecting step of finding a distribution of evaluation values within the predetermined scanning range from a measurement data read-back signal obtained by the measurement data reading unit and detecting, in the distribution of evaluation values, an amount of position displacement of the read head and the write head on the storage medium in a radial direction for storage
18. The head-position-displacement measuring method according to claim 17 , wherein
the measurement data recording step previously sets a target shift amount obtained by dividing a track width by the number of servo sectors for recording in a track perimeter direction at predetermined spacing and, after starting writing from the recording start point, causes the magnetic head to move in a radial direction by the target shift amount upon each servo-sector detection, thereby writing the measurement data in the storage medium while causing the magnetic head to move across at least one track during one lap of track.
19. The head-position-displacement measuring method according to claim 18 , wherein
in the measurement data reading step, after reading from a read-beginning point from which scanning is performed within the predetermined scanning range is started, the magnetic head is caused to move in the radial direction by the target shift amount upon each servo-sector detection, thereby reading the measurement data from the storage medium while the magnetic head is caused to move across at least one track during one lap of track.
20. The head-position-displacement measuring method according to claim 18 , wherein
in the head position displacement detecting step, amplitudes of a read-back signal obtained from the measurement data reading step as the evaluation values are detected, and the amount of position displacement is detected from a peak value in a distribution of the amplitudes.