Eccentricity detection and compensation of a disk by a preformatted encoding pattern

A signal recording apparatus having information data write means for rotating a signal recording medium with a center portion of said signal recording medium engaged with a driving shaft of a rotary driving mechanism and writing information data in a plurality of sectors in either tracks provided on said signal recording medium in the form of concentric circles with respect to the center portion or in a spiral track provided thereon, wherein the improvement comprises:

• reading means for reading an encoding pattern previously provided on said signal recording medium in an area of a concentric circle with respect to said center portion and separate from the sectors and further, reading additional information, which indicates a data structure in the track, previously written on said signal recording medium in an area of a concentric circle with respect to said center portion separate from the sectors and the area in which said encoding pattern is written;
• means responsive to said encoding pattern which is read, for generating a reference pulse signal including a starting point signal indicating a starting point of said encoding pattern
• modulating means for modulating, on the basis of said reference pulse, the frequency of a write clock signal generated in said information data write means for writing said information data onto said signal recording medium;
• starting point detecting means for detecting said starting point signal from said reference pulse signal;
• and
• control signal generating means for generating, on the basis of the starting point signal output from said starting point detecting means and the additional information read by said reading means, a control signal for writing said information data with a write head along the track of said signal recording medium;
• wherein
• said information data are written in positions with said encoding pattern taken as a reference using said modulated write clock signal.

A signal reproducing apparatus having read-out means for reading out information data written in a plurality of sectors in either tracks provided on a signal recording medium in the form of concentric circles with respect to a center portion or in a spiral track provided thereon while said signal recording medium is rotated with the center portion thereof engaged with a driving shaft of a rotary driving mechanism and, further, having read clock signal generating means for reproducing a recorded clock signal corresponding to said information data to thereby generate a read clock for reading out said information data, wherein the improvement comprises:

• reading means for reading an encoding pattern previously provided on said signal recording medium in an area of a concentric circle with respect to said center portion separate from the sectors and further, reading additional information, which indicates a data structure in the track, previously written on said signal recording medium in an area of a concentric circle with respect to said center portion separate from the sectors and the area in which said encoding pattern is written;
• means responsive to said encoding pattern which is read, for generating a reference pulse signal including a starting point signal indicating a starting point of said encoding pattern;
• modulating means for modulating, in accordance with said reference pulse, the frequency of said read clock signal generated in said read clock signal generating means;
• starting point detecting means for detecting said starting point signal from said reference pulse signal and outputting a starting point signal;
• and
• control signal generating means for generating, on the basis of the starting point signal output from said starting point detecting means and the additional information read by said reading means, a control signal for reading out said information data with a read head from a track of said signal recording medium;
• wherein
• said information data are read out from the track using said modulated read clock signal.