US 5,687,036 AGranted

Selection of optimum write current in a disc drive to minimize the occurrence of repeatable read errors

AssigneeSeagate Technology LLC

InventorRoger Jean Kassab

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Abstract

A method for optimizing the write current used by a disc drive read/write transducer to write data to data tracks on a disc. The method optimizes the write current by selecting write currents that minimize the occurrence of repeatable, hard read errors. The method comprises writing a predetermined pattern of information to selected data tracks using each of a plurality of write current values and subsequently reading the data on the selected data track while recording the number of hard read errors for each of the write current values. The optimum write current value is selected at the write current value having the minimum number of hard read errors. An optimum write current value is determined for each of a plurality of locations on the disc and these write current values are stored in the disc drive. During subsequent disc drive write operations, these values are used to determine the optimum write current value for a selected data track through interpolation techniques. Alternatively, for disc drives employing zone-based recording, an optimum write current value can be determined and used for each zone of data tracks on the disc.

Claims10

Dependent claims

In a disc drive having a rotatable disc and an actuator adjacent the disc, the actuator including a read/write transducer for initially writing data to a selected track on the disc by utilizing a write current to selectively magnetize the track during a write operation, the read/write transducer subsequently generating a read signal by detecting the selective magnetization of the track during a read operation, the disc drive further including a read channel for recovering the initially written data from the read signal, a method for optimizing disc drive write performance comprising the steps of:

writing a predetermined data pattern to a selected track using a first write current value having a selected magnitude and subsequently reading the data pattern from the selected track while recording the number of hard errors for the first write current value, further comprising the steps of:
at such time that a read error is detected.
rereading at least a portion of the selected track associated with the read error:
and
classifying the read error as a hard error when the read error reoccurs over a plurality of rotations of the disc:
writing a predetermined data pattern to a selected track using a second write current value having a selected magnitude different from the magnitude of the first write current value and subsequently reading the data pattern from the selected track while recording the number of hard errors for the second write current value, further comprising the steps of:
at such time that a read error is detected,
rereading at least a portion of the selected track associated with the read error;
and
classifying the read error as a hard error when the read error reoccurs over a plurality of rotations of the disc;
selecting an optimal write current value by comparing the number of hard errors for the first write current value to the number of hard errors for the second write current value, the optimal write current value comprising the write current value having the fewest hard errors;
and
storing the optimal write current value in the disc drive and, thereafter, using the optimal write current value during write operations;
wherein at such time that the number of hard errors for the first write current value equals the number of hard errors for the second write current value, the optimum write current value is selected as the write current value having the fewest total number of read errors.

11 more elements

A method for optimizing a write current value in a disc drive having a disc and an actuator adjacent the disc, the actuator including a read/write transducer for writing data to the disc during a write operation and subsequently reading data from the disc during a read operation, the disc including a plurality of nominally concentric tracks, the method comprising the steps of:

identifying a plurality of write current values;
thereafter, for each of the write current values,
providing test data comprising a predetermined sequence of bits;
writing the test data to at least one selected track on the disc to provide recorded data;
reading the recorded data from the disc and comparing the recorded data to the test data;
detecting read errors in the recorded data, each detected read error comprising a discrepancy between a selected portion of the recorded data and a corresponding portion of the test data;
for each detected read error,
rereading the selected portion of the recorded data;
recomparing the selected portion of the recorded data to the corresponding portion of the test data;
and
classifying the read error as a hard error at such time that the error is repeated;
accumulating the total number of read errors and hard errors;
for the plurality of write current values, identifying the optimum write current value as the write current value having the minimum number of hard errors;
storing the optimum write current value on the disc drive;
and,
thereafter, using the optimum write current value to write data to the disc;
wherein at such time that two or more of the write current values have the same minimum number of hard errors, the optimum write current value is identified as the write current value having the minimum number of hard errors and the minimum number of read errors.

14 more elements

In a disc drive having a disc and an actuator adjacent the disc, the actuator having a read/write transducer for writing data to and reading data from concentric tracks on the disc, the disc drive further having write current control circuitry for controlling the magnitude of write current provided to the read/write transducer, the disc drive further including a read channel having error detection and correction circuitry for detecting and correcting up to a selected number of errors in the data read from the tracks, the errors comprising hard errors characterized as comprising repeatable errors and soft errors characterized as comprising non-repeatable errors, an improved method for optimizing the write current in the disc drive comprising the steps of:

(a) selecting a first location on a disc, the first location comprising a plurality of tracks on the disc;
(b) selecting an optimum write current value for the first location on the disc, comprising the steps of:
determining the number of hard errors for each of a plurality of write current values by, for each write current value, writing data to the first location using the write current value, reading data back from the first location and comparing the data written to the first location with the data read back from the first location;
and
selecting the optimum write current value from the plurality of write current values as the write current value having the least number of hard errors, wherein at such time that the least number of hard errors is associated with two or more write current values, selecting the optimum write current value as the write current value having the least number of hard errors and the least number of soft errors;
(c) selecting a second location on a disc, the second location comprising a plurality of tracks on the disc;
(d) selecting an optimum write current value for second location on the disc by repeating step (b) above for the second location;
(e) storing the optimum write current values for the first and second locations;
and, thereafter,
(f) interpolating between the optimum write current values for the first and second locations to determine an optimum write current value for writing data to a selected track on the disc during a disc drive write operation.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/536,958Filed 29 Sep 1995
Granted: 11 Nov 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G11B 20/10481
Improvement or modification of read or write signals: optimisation methods
G11B 5/012
Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor: recording on, or…
G11B 5/035
Analogue recording: equalising
G11B 19/04
Control of operating function, e.g. switching from recording to reproducing: arrangements for preventing, inhibiting, or warning against double…