System and method for detecting deviations in the positioning of a head relative to a track on the disc of a disc storage unit wherein the unit generates a ramp signal having a gradient determined by the position of the track on the disc

DETAILED DESCRIPTION In view of the above, the primary object of the present invention is to provide a system for detecting an off-track amount of the head position in a disc storage unit in which a processing circuit for processing reference information read out through a read/write head can be simplified in construction and the off-track amount of the read/write head position can be detected with a high degree of accuracy.
Another object of the present invention is to provide a system for detecting an off-track amount of a head position in a disc storage unit in which reference information is written in the disc in a simple manner and without requiring a high degree of accuracy, in and which the area of regions on the surface of the disc required for the storage of reference information is reduced much as is practically possible.
A further object of the present invention is to provide a system for detecting an off-track amount of a head position in a disc storage unit in which the off-track amount of the read/write head position is determined with a high degree of accuracy without being adversely affected according to the radial positions of the surface ot the disc at which reference information is stored.
In order to accomplish the foregoing and other objects and ends, according to the present invention, a repetitive pattern is stored as reference information in each region in such a way that it is deviated in the longitudinal direction of a track from the repetitive patterns stored in the adjacent regions.
When the reference information in the two adjacent regions is read out by the read/write head, a ramp signal whose gradient is varied depending upon the position of the desired track on the surface of the disc is generated in synchronism with the readout of the reference information.
The ramp signal is used as a threshold value and the numbers of the repetitive pattern signals obtained from the signals read out from the reference information in the two adjacent regions which are in excess of the threshold value is counted