Hitachi Global Storage Technologies Netherlands B.v.

Junzoh Noda

Masahiro Shimizu

Yasuhiro Iihara

Atsushi Tobari

Masaki Kudoh

Hiroyasu Masuda

Masanori Aratani

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 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

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Kanagawa, Japan

Junzoh Noda