Sensitivity correcting circuit of servo signal detection on data surface

Abstract

A sensitivity correcting circuit offsets a data head outwardly from an ontrack position by a given quantity (X1), reads first and second servo information (A, B) to provide signals (V.sub.A, V.sub.B), and detects a difference (V1) between the peak values of the signals. Also, the system offsets the data head inwardly from the ontrack position by a given quantity (X2), reads the first and second servo information (A, B) to provide signals (V.sub.A, V.sub.B), and detects a difference (V2) between the peak values of the signals (V.sub.A, V.sub.B). The circuit then computes a proportional coefficient K according to the detected values (V1, V2), and according to the proportional coefficient, finds an offset specific to the data head. Or an offset measuring circuit comprises an offset detector for detecting offsets of data heads relative to a servo head according to servo information read by the data heads on data surfaces of the disk media; a measurement timing setting circuit for instructing the offset detector to start a detection process according to a predetermined time schedule; and an interrupter for interrupting, if the command control section decodes an access command such as a read or write command provided by the host unit, the offset detection process, executing the access command at first, and resuming the offset detection process after the access command is completed when the detection process by the offset detector is executed.