Patent ID: 6738216
Filing Date: 2004-05-18
Classification: G11B

Abstract:
A disk drive apparatus comprising:a disk medium including a data area on which data is recorded; an actuator which supports a head used to read/write data from/to the data area of the disk medium and drives the head in a radial direction of the disk medium, wherein the head is a composite head including a magnetoresistive head used as a read head and an inductive head used as a write head, and the magnetoresistive head serves as both the read head and a magnetic field detector which detects an externally applied magnetic field; a head retracting mechanism into which the head is retracted from the data area of the disk medium; head load means for performing a head load operation to drive the actuator and move the head from the head retracting mechanism to the data area of the disk medium; control means for checking a result of detection obtained from the magnetic field detector while the head is retracted into the head retracting mechanism and inhibiting the head load means from performing the head load operation in accordance with the result of detection; a head amplifying circuit which supplies a bias current to the magnetoresistive head and amplifies an output of the magnetoresistive head, the output corresponding to a resistance value of the magnetoresistive head which varies with a magnetic field applied to the magnetoresistive head; and an A/D converter which converts the output of the magnetoresistive head amplified by the head amplifying circuit into a digital value, wherein when the head load means performs the head load operation, the control means supplies a preset bias current to the magnetoresistive head from the head amplifying circuit, receives the output of the magnetoresistive head, which is amplified by the head amplifying circuit, through the A/D converter, and processes the output as the result of detection.