System and method for setting a read/write offset and for recovering from data read errors

A read data error recovery method for recovering a read data error of recorded data in a disk device including a rotary actuator having a head section for accessing a disk recording medium, comprising the steps of:

• [A] determining an off-track direction where an amplitude increases, by moving said head section to off-track positions on both sides of an on-track nominal position and measuring an amplitude of read back signals by a read head in the limited vicinity of a data sector where a read data error occurs;
• [B] searching an off-track position where said amplitude becomes a local maximum by gradually shifting said head section in the off-track direction where said amplitude increases and measuring said amplitude at each off-track position;
• and
• [C] reading data recorded in said data sector by moving said head section to the off-track position where said amplitude becomes a local maximum.

A read data error recovery method for recovering a read data error of recorded data in a disk device with a rotary actuator having a head section for accessing a disk recording medium, said method comprising the steps of:

• [A] performing tracking with said head section at a plurality of different tracking positions in a predetermined search range with regard to a track where said read data error occurs and measuring respective amplitudes of read head signals by the head section in the vicinity of a data sector where the read data error occurs;
• [B] finding an approximate expression of a profile of the measured amplitude for each of the plurality of tracking positions and finding a position, where a maximum value is given in said approximate expression, as a tracking position where amplitude of the read back signal reaches a maximum value;
• [C] tracking to a position with said head section where the amplitude maximizes;
• and
• [D] reading data recorded in the data sector.

A disk device comprising:

• a disk recording medium having a plurality of sectored tracks in which data are recorded;
• a head section including a write head and a read head for accessing data recorded on said disk recording medium;
• a rotary actuator for moving said head section in a radial direction of said disk recording medium;
• and
• a control unit for controlling said rotary actuator, said control unit including means for recovering a read data error of recorded data, said means for recovering including:
• means for determining an off-track direction where an amplitude increases, by moving said head section to off-track positions on both sides of an on-track nominal position and measuring an amplitude of read back signals by a read head in the limited vicinity of a data sector where a read data error occurs;
• means for searching an off-track position where said amplitude becomes a local maximum by gradually shifting said head section in the off-track direction where said amplitude increases and measuring said amplitude at each off-track position;
• and
• means for reading data recorded in said data sector by moving said head section to the off-track position where said amplitude becomes a local maximum.

A disk device comprising:

• a disk recording medium having a plurality of sectored tracks in which data are recorded;
• a head section for accessing data recorded on said disk recording medium;
• a rotary actuator for moving said head section in a radial direction of said disk recording medium;
• and
• a control unit for controlling disk access by said head section, said control unit including means for recovering a read data error of recorded data, said means for recovering including:
• means for performing tracking with said head section at a plurality of different tracking positions within a predetermined search range of a track where said read data error occurs and measuring respective amplitudes of read head signals by the head section in the vicinity of a data sector where the read data error occurs;
• finding an approximate expression of a profile of the measured amplitude for each of the plurality of tracking positions and finding a position, where a maximum value is given in said approximate expression as a tracking position where amplitude of the read back signal reaches a maximum value;
• tracking to a position with said head section where the amplitude maximizes;
• and
• reading data recorded in the data sector.

A disk device, comprising:

• a disk recording medium having a plurality of sectored tracks in which data are recorded;
• a head section including a write head and a read head for accessing said disk recording medium;
• a rotary actuator for moving said head section in a radial direction of said disk recording medium;
• and
• a control unit for controlling disk access by said head section, said control unit including means for configuring said disk drive to compensate for a RW offset between the write head and the read head, said means for configuring including:
• means for recording a test pattern utilizing said write head in each of a plurality of tracks of said disk recording medium;
• means for reading said test patterns utilizing said read head at a plurality of different tracking positions for each of the plurality of tracks, and measuring an amplitude of a read back signal at each tracking position;
• means for finding an approximate expression of a profile of the measured amplitude at each of said plurality of tracking positions for each of said plurality of tracks to be measured;
• means for finding a tracking position that gives a maximum value of said approximate expression of each of said plurality of tracks to be measured;
• means for determining, based upon the tracking position found for each measured track, a plurality of coefficients of a track-dependent arithmetic expression by which a RW offset for any track in said disk device can be calculated;
• and
• means for storing said plurality of coefficients within said disk device.