Phase adjusting device, magnetic storage medium, and storage device
View Patent ↗A magnetic storage medium such as a BPM includes a plurality of magnetic dots for writing and reproducing data disposed in a magnetically separated manner so as to be spaced a predetermined distance in a down-track direction and a plurality of tracks concentrically disposed so that the magnetic dots are disposed in a magnetically separated manner. In the BPM, a phase-adjusting track is disposed in an arbitrary track among the tracks. On the phase-adjusting track, phase detection dots disposed in a down-track direction to allow writing and reproduction of phase detection data and blank bits providing a predetermined phase difference in a down-track direction to next successive phase-detecting dots are alternately disposed in a successive manner.
1. A phase adjusting device comprising:
a rotation drive controlling unit that drives a magnetic storage medium for rotation, the magnetic storage medium having a plurality of magnetic dots disposed along a down-track direction in a magnetically separated manner and phase-detecting dots and blank bits alternately disposed along a phase-adjusting track provided between adjacent lines of the magnetic dots in a cross-track direction to provide a predetermined phase difference in the down-track direction;
a magnetic-head drive controlling unit that adjusts and controls a write timing and a reproduction timing of a magnetic head unit with respect to the magnetic dots of the magnetic storage medium;
a position-information managing unit that manages position information of the phase-detecting dots in the phase-adjusting track;
a write controlling unit that, upon detecting a phase-detection start signal, starts writing of phase detection data by repeatedly reversing a magnetizing direction with a predetermined period of dot counts on the phase-adjusting track via the magnetic head unit and manages a write start position thereof;
a reproduction controlling unit that, after the phase detection data is written, reproduces and outputs the phase detection data written in the phase-detecting dots on the phase-adjusting track in accordance with a reproduction timing of the magnetic head unit at the write start position;
a reproduction-output-waveform obtaining unit that obtains a reproduction output waveform of the phase detection data written in the phase-detecting dots on the phase-adjusting track reproduced and output by the reproduction controlling unit;
a maximum-output-pattern detecting unit that detects an output pattern with a maximum peak at a minus side and a plus side of the reproduction output waveform obtained by the reproduction-output-waveform obtaining unit;
a zero-cross-position detecting unit that detects a zero-cross position regarding the output pattern of the maximum peak detected by the maximum-output-pattern detecting unit; and
an optimum-phase-adjustment-amount determining unit that determines an optimum phase-adjusting amount for matching a phase of the write timing of the magnetic head unit with respect to the magnetic dots of the magnetic storage medium based on the zero-cross position detected by the zero-cross-position detecting unit and the position information of the phase-detecting dots managed by the position-information managing unit.
2. The phase adjusting device according to claim 1 , further comprising a reference-clock obtaining unit that obtains a reference clock from reproduction output, wherein
upon detecting a zero-cross regarding the output pattern of the maximum peak detected by the maximum-output-pattern detecting unit, the zero-cross-position detecting unit detects the zero-cross position based on the number of reference clocks from the write start position to the detection of the zero-cross.
3. A magnetic storage medium comprising:
a plurality of magnetic dots disposed along a down-track direction in a magnetically separated manner; and
phase-detecting dots and blank bits alternately disposed along a phase-adjusting track provided between adjacent lines of the magnetic dots in a cross-track direction to provide a predetermined phase difference in the down-track direction.
4. The magnetic storage medium according to claim 3 , wherein
the phase-detecting dots are formed of a predetermined number of magnetic dots disposed each with the predetermined space, and
with a distance obtained by adding a distance corresponding to a length of the phase-detecting dots in the down-track direction and a distance corresponding to a predetermined fraction of the dot length of the magnetic dots in the down-track direction being taken as a length of the blank bits in the down-track direction, the blank bits provide a predetermined phase difference of the distance corresponding to the predetermined fraction of the dot length of the magnetic dots to next successive phase-detecting dots in the down-track direction.
5. The magnetic storage medium according to claim 4 , wherein
the phase-detecting dots are formed of four magnetic dots disposed each with the predetermined space, and
with a distance obtained by adding a distance corresponding to a length of the phase-detecting dots formed of four magnetic dots disposed each with the predetermined space and a distance corresponding to one-third of the dot length of the magnetic dots being taken as a length of the blank bits in the down-track direction, the blank bits provide a predetermined phase difference of the distance corresponding to one-third of the dot length of the magnetic dots to next successive phase-detecting dots in the down-track direction.
6. A storage device comprising:
a magnetic storage medium having a plurality of magnetic dots disposed along a down-track direction in a magnetically separated manner and phase-detecting dots and blank bits alternately disposed along a phase-adjusting track provided between adjacent lines of the magnetic dots in a cross-track direction to provide a predetermined phase difference in the down-track direction;
a magnetic head unit that writes data in the magnetic dots of the magnetic storage medium and reproduces the data from the magnetic dots of the magnetic storage medium;
a rotation drive controlling unit that drives the magnetic storage medium for rotation; and
a magnetic-head drive controlling unit that adjusts and controls a write timing and a reproduction timing of the magnetic head unit with respect to the magnetic dots of the magnetic storage medium.
7. The storage device according to claim 6 , further comprising:
a position-information managing unit that manages position information of the phase-detecting dots in the phase-adjusting track;
a write controlling unit that, upon detecting a phase-detection start signal, starts writing of phase detection data by repeatedly reversing a magnetizing direction with a predetermined period of dot counts on the phase-adjusting track via the magnetic head unit and manages a write start position thereof;
a reproduction controlling unit that, after the phase detection data is written, reproduces and outputs the phase detection data written in the phase-detecting dots on the phase-adjusting track in accordance with a reproduction timing of the magnetic head unit at the write start position;
a reproduction-output-waveform obtaining unit that obtains a reproduction output waveform of the phase detection data written in the phase-detecting dots on the phase-adjusting track reproduced and output by the reproduction controlling unit;
a maximum-output-pattern detecting unit that detects an output pattern with a maximum peak at a minus side and a plus side of the reproduction output waveform obtained by the reproduction-output-waveform obtaining unit;
a zero-cross-position detecting unit that detects a zero-cross position regarding the output pattern of the maximum peak detected by the maximum-output-pattern detecting unit; and
an optimum-phase-adjustment-amount determining unit that determines an optimum phase-adjusting amount for matching a phase of the write timing of the magnetic head unit with respect to the magnetic dots of the magnetic storage medium based on the zero-cross position detected by the zero-cross-position detecting unit and the position information of the phase-detecting dots managed by the position-information managing unit.
8. The storage device according to claim 6 , wherein
the phase-detecting dots are formed of a predetermined number of magnetic dots disposed each with the predetermined space,
with a distance obtained by adding a distance corresponding to a length of the phase-detecting dots in the down-track direction and a distance corresponding to a predetermined fraction of the dot length of the magnetic dots in the down-track direction being taken as a length of the blank bits in the down-track direction, the blank bits provide a predetermined phase difference of the distance corresponding to the predetermined fraction of the dot length of the magnetic dots to next successive phase-detecting dots in the down-track direction.