Hitachi Global Storage Technologies Netherlands B.v.

Hitachi Global Storage Technologies

Atsushi Tobari

Masaomi Ikeda

Masahiro Shimizu

Satoshi Hashimoto

Yasuhiro Iihara

Hiroyasu Masuda

Masanori Aratani

Kaoru Iseri

Junzoh Noda

Masahide Yamasaki

Junzou Noda

Takao Matusi

Kouji Matsuda

Embodiments of the present invention help to efficiently determine the appropriate setting of the write current of a magnetic head relative to temperature. According to one embodiment, a test computer determines the set value of a write current as a function of temperature for each head device portion from the relationship between a write current and an error rate. A test execution controller sets a selected head device portion and a write current to an AE, and writes data on a magnetic disk using the components in a HDD. The test execution controller reads the written data, and the error rate of the data from an error correcting section. The test execution controller repeats the same process with the write current varied. Upon completion of the measurement at the preset write currents, the test execution controller transfers the measurement data to the test computer.

Method and apparatus for determining set value of write current of magnetic head

Embodiments of the invention prevent offtrack write that will be caused due to a head vibration in a storage device. In one embodiment, a hard disk drive (HDD) judges approval/disapproval of write of user data to a magnetic disk by using a read signal for user data in addition to servo data in write processing. Thus, a head vibration which cannot be precisely detected based on servo data is detected to prevent off-track write. More specifically, the HDD acquires a read back signal amplitude of a read element with respect to a user data sector within adjacent servo data during a write access phase, and detects a vibration from a maximum value MAX and a minimum value MIN of the read back signal amplitude to judge data write approval/disapproval.

Off track write protection for data storage device

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

Embodiments of the invention provide a magnetic disk drive that does not generate errors when information is read even if considerable time has elapsed after the information was written on the magnetic disk. In one embodiment, a magnetic disk has a storage area divided into a plurality of sectors ST. Time stamps TPcorresponding to each sector data mstored in the sectors STare stored in a time stamp recording medium. A processor controls the magnetic disk drive to read time stamps TPof sector data mstored in any sectors STof the sectors STand refresh sector data mselected based on an elapsed time calculated from information about the time when the time stamps are read and the time stamps TP

Magnetic disk drive and refresh method

Growing community of inventors

Kanagawa, Japan

Atsushi Tobari