Recording current control method and magnetic disk drive
AssigneeHitachi Global Storage Technologies Japan, Ltd.
InventorsTakeshi Doi, Masayoshi Shimokoshi, Hitoshi Yoshida
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Abstract
In a magnetic disk drive, a writing element and its surrounding area thermally expand due to the heat generated by a write head coil. The transient phenomenon of such thermal expansion may invoke the transient phenomenon of inadequate writing capacity, thereby causing a writing error at an early stage of a write operation. Control is provided which increases/decreases either or both the write current to be applied to a write head and the amount of its overshoot on an individual sector basis during a writing sequence.
Claims12
A method of controlling a write current in a magnetic disk drive, the method comprising:
- receiving a write command to initiate a present write operation;
- and
- if a predetermined period of time has elapsed since a most recent write operation terminated,
- applying a given write current to a write head coil at the beginning of the present write operation, and
- decreasing the write current during the present write operation in multiple steps the number of which depends on the number of recording operation interruptions, wherein the write current is less than the given write current at the end of the write operation;
- or
- if said predetermined period of time has not elapsed since the most recent write operation terminated, applying a write current less than the given write current at the beginning of the present write operation.
A method of controlling a write current in a magnetic disk drive, the method comprising:
- receiving a write command to initiate a present write operation;
- and
- if a predetermined period of time has elapsed since a most recent write operation terminated,
- applying a first write current to a write head coil during a first portion of the present write operation, and
- applying a second write current during a second later portion of the present write operation, wherein the first write current is higher than the second write current, the write current being decreased from the first write current to the second write current in multiple steps the number of which depends on the number of recording operation interruptions;
- or
- if said predetermined period of time has not elapsed since a most recent write operation terminated, applying the second write current during the first and second portions of the present write operation.
A magnetic disk drive comprising:
- a magnetic disk that rotates during operation;
- a write head having a coil through which a write current is passed during a write operation;
- and
- a write current control circuit that causes said write current to decrease in multiple steps, the number of which depends on the number of recording operation interruptions, during a write operation so that for an initial portion of the write operation, the write current being higher than the write current for an ending portion of the write operation.
A magnetic disk drive using a magnetic head for energizing a coil when information targeted for storage is divided into specified segments and is written onto a magnetic disk medium,
- wherein said magnetic disk drive has means for setting the value of write current to be supplied to the coil for each of said specified segments and recording information while varying the write current in multiple steps, the number of which depends on the number of recording operation interruptions, during a writing sequence.
Dependencies are inferred from the claim text.