Disk recording medium including data pre-formatted-data-recorded header having first and second identical address numbers radially displaced from each other on opposite sides of groove or land track center line, and disk drive unit for use with the recording medium

A disk recording medium comprising recording tracks including groove tracks and land tracks that each have sectors as data units, wherein:

• a) each of said sectors includes:
• 1) a preformatted-data-recorded header area that includes a first address and a second address that have identical address numbers and that are radially displaced from each other on opposite sides of a center line of one groove track or one land track;
• and
• 2) a writing/reading area in which data is written or read;
• wherein:
• a plurality of zones are radially formed on said disk recording medium;
• and
• in at least one zone, different logical addresses are assigned to said groove tracks and said land tracks.

A disk drive unit for use with a disk recording medium that has recording tracks including groove tracks and land tracks that each have sectors as data units, wherein each of said sectors includes:

• 1) a preformatted-data-recorded header area that includes a first address and a second address that have identical address numbers and that are radially displaced from each other on opposite sides of a center line of one groove track or one land track;
• and
• 2) a writing/reading area in which data is written or read;
• said disk drive unit comprising:
• a) head means for writing/reading information to/from said groove tracks and said land tracks;
• and
• b) control means for controlling said head means to perform a writing operation or a reading operation based on a sector address on the groove track or a sector address on the land track, the sector being determined using the address values read by said head means at said first address and said second address;
• c) servo means for switching scanning modes of writing or reading by said head means, the scanning modes corresponding to the scanning of said groove tracks and the scanning of said land tracks;
• wherein said control means determines, based on the scanning mode switched by said servo means and the two address values at said first address and said second address, the sector address on the groove track or the sector address on the land track.

A disk drive unit for use with a disk recording medium that has recording tracks including groove tracks and land tracks that each have sectors as data units, wherein each of said sectors includes:

• 1) a preformatted-data-recorded header area that includes a first address and a second address that have identical address numbers and that are radially displaced from each other on opposite sides of a center line of one groove track or one land track;
• and
• 2) a writing/reading area in which data is written or read;
• said disk drive unit comprising:
• a) head means for writing/reading information to/from said groove tracks and said land tracks;
• and
• b) control means for controlling said head means to perform a writing operation or a reading operation based on a sector address on the groove track or a sector address on the land track, the sector being determined using the address values read by said head means at said first address and said second address;
• wherein:
• a plurality of zones which are radially formed on the said disk recording medium;
• and
• when said head means scans either the groove track or the land track, said control means specifies one zone based on the difference between the two address values read at said first address and said second address.