The position shift detection device and method of detection null of the head in the

摘要

PURPOSE:To accurately detect the positional deviation of a data head by recording plural kinds of servo pattern information extended over three or more areas on the outer and inner peripheral sides of a cylinder for measurement and detecting these information based on the read result. CONSTITUTION:Areas 10 to 16 are allocated on inner and outer peripheral sides of the cylinder for measurement with this cylinder as the center with the core width of a data head l as a unit. Servo patterns 17 to 19 are provided to extend over three or more areas 14 to 16, 11 to 15 11 to 12 and 15, 16 out of these areas 10 to 16, and '010', '011'... are read in accordance with the area position of the head 1. Patterns 20, 21, 22, and 23 for positional deviation detection are provided in the same manner, and the positional deviation of the head 1 from boundary lines of adjacent areas 10 to 16 is detected by the difference of the read peak value, and detection is repeated plural time while performing the feedback control to secure the linearity characteristic in a wide range, and the head positional deviation is quickly and accurately detected without influences of disk eccentricity and inter-head positional deviation.