Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Yasuhiro Iihara

Masanori Aratani

Masahiro Shimizu

Isao Yoneda

Kohji Takasaki

Nobuhiko Wasa

Masaki Kudoh

Atsushi Tobari

Yoshiroh Amano

Toshihisa Kiyonaga

Junzoh Noda

Kaoru Iseri

Yoshifumi Kataoka

A HDD including write components configured to operate within an operating voltage range, charging circuitry comprising a charging capacitor. The charging capacitor includes a higher voltage when charged than the operating voltage range. The HDD also includes pulse circuitry configured to pulse power from the charging circuitry to the write components within the operating voltage range during a controlled shut down of the write components such that remaining data-sector bits are written during the controlled shut down.

Pulse power during a shut down in a hard disk drive

Embodiments of the present invention help to perform appropriate servo control in response to detected vibration in a disk drive device having a vibration sensor. In an embodiment of the present invention, an HDD switches a correction servo mode to perform vibration correction in head positioning and a normal servo mode not to perform the vibration correction. The HDD performs servo positioning in either one of the serve modes and determines servo positioning accuracy in the servo mode from the measured positional error signal. The HDD obtains data indicating the servo positioning accuracy in the other servo mode from a table. The HDD compares the accuracy in the two servo modes and selects the servo mode with higher accuracy. The table contains previous measurements on servo positioning accuracy in the servo modes.

Disk drive device and servo control method thereof

Embodiments of the present invention provide an inspection method for detecting a physical defect of a magnetic disk with high sensitivity without increasing the length of inspection time. In a magnetic disk drive according to one embodiment, the assembling of which has been completed, by reading inspection data written to a magnetic disk, a defect of the magnetic disk is detected in a state in which a read error occurs. Redundant bits of an ECC are added to the inspection data. If a head corresponding to a recording surface to be inspected has superior read performance, an ECC 2 is applied. If the head in question has inferior read performance, an ECC 4 is applied. Accordingly, as compared with a case where a single ECC is applied, the defect detectivity is further improved without increasing the length of inspection time.

Surface analysis test with mixed ECC symbol

Embodiments of the invention avoid an off-track write when an impact is applied. A hard disk drive according to one embodiment of the present invention comprises a magnetic disk; an actuator for moving a head element section over the magnetic disk; and an HDC/MPU for prohibiting the head element section from writing onto the magnetic disk for a short period when a detected impact is found to be greater than a low reference level and not greater than a high reference level, and prohibiting the head element section from writing onto the magnetic disk for a period longer than the short period when the detected impact is found to be greater than the high reference level.

Data storage device and data storage device control method

Growing community of inventors

Kanagawa, Japan

Yasuhiro Iihara