Patent ID: 7511906

Claim:
A disk device comprising a disk drive unit for pivotally driving a disk; a magnetic head including a recording head element for recording information at arbitrary positions in a plurality of tracks formed in a region ranging from an inner circumferential portion to an outer circumferential portion of the disk and also including a reproducing head element for reproducing the information recorded at the arbitrary positions in the plurality of tracks and also including a heater element arranged close to the recording head element or the reproducing head element so as to heat the recording head element or the reproducing head element; a head drive unit for driving the magnetic head so that the magnetic head can be moved between the plurality of tracks of the disk; and a control unit for controlling various operations including an operation of writing information at arbitrary positions of the disk with the magnetic head and also including an operation of reading out the information written at the arbitrary positions, wherein; a single frequency data region is previously formed at a predetermined position in each track of the disk, a single frequency of the single frequency data region is set at a frequency of about Â½ of the maximum frequency corresponding to the maximum transfer bit speed in each track, the disk device further comprising a modulation detecting means for detecting the generation of modulation, which is caused by contact between the magnetic head and the disk, on the basis of a regenerative signal of the single frequency data region reproduced by the reproducing head element when the magnetic head is moved to a predetermined position of each track, wherein; the modulation detecting means includes: a regenerative signal output level detecting unit for detecting an output level of the regenerative signal of the single frequency data region reproduced by the reproducing head element; and a Fourier transform unit for carrying out a Fourier transform on the regenerative signal detected by the regenerative signal output level detecting unit, wherein; when a regenerative signal frequency component corresponding to the modulation frequency is extracted by the Fourier transform unit, the generation of the modulation is detected, and when the generation of the modulation is detected, the control unit reduces an amount of protrusion of the recording head element or the reproducing head element by decreasing an intensity of electric power supplied to the heater element.