Abstract: A magnetic disk apparatus using a servo-surface servo and a data-surface servo is disclosed which comprises a servo disk which is disposed on a rotating axis and which has a servo surface on which first servo information is written and a data disk which is disposed on the rotating axis and which has a data surface. A servo head is provided for reading the first servo information from the servo disk and a read/write head is provided which works in association with the servo head for reading and writing information from and to the data surface. Structure is provided to generate a second servo information to be written on the data surface, to command a write timing of the second servo information, to control the write operation, and to control the positioning of the read/write head position. Thus, according to servo information being read from the servo head, servo information to be written to the data surface is generated and written to the data surface.

Abstract: In a head driving control apparatus used, for example, in a hard disc drive, a peak detector detects a peak value of a servo signal output from a data head. A CPU detects a thermal off-track distance L of the data head, on the basis of the peak value of the servo signal. When the thermal off-track distance L is within an allowable off-track distance Lw in a data write mode or within an allowable off-track distance Lc in a data read mode, the CPU enables a data write operation or a data read operation. When the thermal off-track distance L is without the allowable off-track distance Lw in the data write mode or without the allowable off-track distance Lc in the data read mode, the CPU prohibits the data write operation or the data read operation.

Abstract: According to the invention, a magnetic head positioning control apparatus using an index servo data has a circuit for determining a final correction value such that a magnetic head position correcting operation is repeatedly performed at a designated track position. The apparatus also has a circuit for obtaining final correction values for two different tracks, to calculate a thermal offset value accordingly. A correction current value and a track position can be expressed by a linear relation, and two coefficients of the relation can be determined using the two final correction current values. When an arbitrary track position is designated, a thermal offset value can be determined with reference to the two coefficients of the relation and the designated track position.

Abstract: A signal detector of a magnetic disk apparatus has a comparator for generating a pulse signal when an analog signal from a magnetic head for performing the read/write operation of data falls within a range between predetermined voltage levels, a flip-flop for receiving an output signal from the comparator and for generating the signal required in converting a peak of the analog signal to a digital signal, in accordance with the output signal from the comparator, and a gate circuit for supplying a clock pulse to the flip-flop, said clock pulse corresponding to the zero-crossing point of the differential signal for detecting the peak of the analog signal and having a predetermined pulse width, in response to the output signal from the comparator.