Hitachi Global Storage Technologies Netherlands B.v.

Sayaka Nojiri

Nobuhiko Wasa

Shinya Sakamoto

Hirofumi Saitoh

Kenichi Kuramoto

Shinji Matsushita

Hidefumi Tominaga

Naoya Tsurusaki

Embodiments of the present invention improve the safety against a fall of a disk drive device. In one embodiment, when an HDD has recognized detection result data of a fall sensor to indicate a fall, the HDD unloads a head slider from above a disk to a stand-by position. The HDD checks whether or not the detection result data of the fall sensor indicates a fall on the occasion of a seek start. If the data indicates a fall, the controller unloads an actuator. The HDD issues a seek fake error on the occasion of a seek completion. On the occasion of a re-seek start in the error recovery process, the HDD conducts a fall check referring to the detection result data.

Disk drive device and control method of unloading corresponding to fall detection in disk drive device

Embodiments of the present invention help to prevent destabilization in voice coil motor (VCM) velocity control. According to one embodiment, a hard disk controller/multiprocessing unit (HDC/MPU) calibrates a correction operational coefficient of a detected back electromotive force (EMF) voltage before unloading. The calibration is carried out in a state that an actuator is pivoting. The HDC/MPU calibrates the correction coefficient according to a motion equation of the actuator using VCM current applied to a VCM and a detected value of a back EMF voltage detection circuit.

Disk drive and calibration method therefor

Embodiments in accordance with the present invention provide a disk drive capable of verifying whether the speed of an actuator is true or not, the speed being detected while the actuator is being moved between a retracted position and a recording surface of a magnetic disk, and to provide a control method for controlling the disk drive. In a particular embodiment, a hard disk drive (HDD) comprises: a head for accessing a disk; an actuator for supporting the head, the actuator being driven by a voice coil motor (VCM); a speed monitor for, on the basis of a cylinder ID written to the disk, monitoring the speed of the actuator while the actuator is being moved between a ramp which is provided outside a data area of the disk and the data area; and a speed verifier for, if an abnormal speed condition of the actuator is detected by the speed monitor, verifying the abnormal speed condition on the basis of the counter electromotive voltage of the VCM. If the speed based on the counter electromotive voltage is also abnormal, the speed verifier records the speed as the overspeed.

Disk drive and control method therefor

In an embodiment of the present invention, a Hard Disk Controller Microprocessing Unit (HDC/MPU) supplies, prior to the unloading process, different currents to a VCM, with an actuator positioned in place and kept at a standstill. The HDC/MPU determines a correction factor from VCM speeds vmeas, each of which is detected at each of VCM currents Ivcm. If the determined correction factor falls outside a reference limit, the HDC/MPU determines a new circuit parameter for a VCM speed detection circuit. Further, the HDC/MPU calculates a new correction factor appropriate to the circuit parameter. The HDC/MPU and the VCM speed detection circuit control the speed of the VCM in the unloading process using the new circuit parameter and the new correction factor.

Growing community of inventors

Kanagawa, Japan

Sayaka Nojiri