Hitachi Global Storage Technologies Netherlands B.v.

Yumi Nagano

Toyomi Ohsawa

Nobumasa Nishiyama

Noriaki Satoh

John Thomas Contreras

Mike Suk

Masayuki Kurita

Masato Taniguchi

Yoshiaki Uji

Michio Nakajima

Kouji Miyake

Takashi Ikeda

Embodiments in accordance with the present invention reduce the structural stress applied to a head, and to achieve the effective control, when the clearance between the head and a disk is adjusted by using a heater. According to one embodiment, the hard disk controller/microprocessing unit (HDC/MPU) controls a slew rate of a heater at the time of TFC (Thermal Fly height Control). In response to processing conditions, a HDC/MPU changes a slew rate of the output of electric current/voltage applied to the heater. This makes it possible to reduce the head stress, and to achieve the effective TFC. To be more specific, with reference to a temperature/slew rate table, the HDC/MPU changes a slew rate in response to the temperature in the read/write processing.

Disk drive and control method thereof

Embodiments in accordance with the present invention reduce the number of errors caused by the aged deterioration of a heater for adjusting the clearance between a head and a disk. According to one embodiment, a thermal fly height control (TFC) controller executes the measurement of a resistance value of a heater in a predetermined timing. The TFC controller judges whether or not the measured resistance value falls within a predetermined reference range. If the measured resistance value falls within the reference range, the processing ends without performing any other processing. If the measured resistance value goes out of the reference range, the TFC controller executes error handling processing in response to a resistance failure. As one of the error handling processing, the TFC controller notifies the host that the abnormality (resistance failure) has been detected in the resistance value of the TFC heater.

Embodiments of the invention make it possible to conduct stable recording on a magnetic disk, even in case of changes in flying height due to thermal protrusion. In one embodiment, a compensatory recording current value Ais used when a first section of user data is recorded in the required number of data sectors from the data sector of the starting address for recording the user data to the data sector of an intermediate address. A recording current value Asmaller than the compensatory recording current value is used when a second section of user data is recorded in the data sectors existing from the data sector of the intermediate address towards the ending address.

Method of controlling a recording current, and magnetic disk device

A system and method for preventing crosstalk noise from being superimposed on a read signal due to noise from a heater line for a slider in a recording disk drive is disclosed. A heater line pair to the slider is not grounded but is in a floating state with respect to an actuator support structure. A heater driver allows a heater current to flow between a positive power supply voltage and a negative power supply voltage. The heater line pair is not grounded, so an impedance is high as viewed from a magnetic disk. Thus, it is possible to effectively suppress a noise transmitted from the magnetic disk and read signal quality is kept from deteriorating due to the crosstalk from the heater line.

Recording disk drive with reduced noise thermal flyheight control

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Kanagawa, Japan

Yumi Nagano