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US 7,009,792 B2Granted
Method and apparatus for data reproducing in a disk drive
AssigneeKabushiki Kaisha Toshiba
InventorsYuji Sakai, Koji Osafune
Life of this patent
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Abstract
A perpendicular magnetic recording type of disk drive having function of removing a component of a shift in a base line of a reproducing signal is to be disclosed. The disk drive has a read channel including an extracting unit which extracts the component of the shift in the base line of the reproducing signal. The extracting unit includes low-pass filters, and parameters of a lower cut-off frequency of the low-pass filter are adjusted in read operation.
Claims12
A disk drive for perpendicular magnetic recording, comprising:
- a head which reads out a data signal recorded in a disk medium;
- and
- a read channel which includes a signal processing unit having lower cut-off frequency characteristics and including a high-pass filter which carries out removal of low-frequency noise of the data signal outputted from the head and a decoding unit which decodes recording data from the data signal,
- wherein the read channel includes:
- an extracting unit which extracts a component of a shift in a base line of the data signal processed by the signal processing unit, and
- a compensating unit which removes the component of the shift in the base line from the data signal, and
- wherein the extracting unit has:
- a generator which generates an ideal data signal;
- a subtracting unit which outputs a difference data signal according to difference between the ideal data signal and a data signal processed by the signal processing unit;
- and
- an adjusting unit including a gain adjusting circuit and a high-frequency cut-off filter, which process the difference data signal, the adjusting unit generating a signal corresponding to the component of the shift in the base line.
8 more elements
A disk drive for perpendicular magnetic recording, comprising:
- a head which reads out a data signal recorded in a disk medium;
- and
- a read channel which includes a signal processing unit having lower cut-off frequency characteristics and including a high-pass filter which carries out removal of low-frequency noise of the data signal outputted from the head and a decoding unit which decodes recording data from the data signal,
- wherein the read channel includes:
- an extracting unit which extracts a component of a shift in a base line of the data signal processed by the signal processing unit, and
- a compensating unit which removes the component of the shift in the base line from the data signal, and
- wherein the extracting unit has:
- a generator which generates an ideal data signal;
- a subtracting unit which outputs a difference data signal according to difference between the ideal data signal and a data signal processed by the signal processing unit;
- and
- an adjusting unit including a gain adjusting circuit and an integrating circuit, which have high-frequency cut-off characteristics processing the difference data signal, the adjusting unit generating a signal corresponding to the component of the shift in the base line.
8 more elements
A disk drive using a disk medium in which a plurality of groups of data tracks for recording a data signal is formed by a perpendicular magnetic recording method and each group of data tracks is managed in each plurality of zones, comprising:
- a head to read out a data signal recorded in a disk medium in read operation;
- and
- a read channel to process the data signal outputted from the head by a PRML signal processing method to reproduce recording data,
- wherein the read channel includes:
- a high-pass filter circuit having lower cut-off frequency characteristics;
- a signal processing unit which generates sample data obtained from the data signal outputted from the high-pass filter circuit by a PR type of waveform equalizing processing;
- a decoding unit to decode the recording data from the sample data;
- an extracting unit which extracts a component of a shift in a base line included in the data signal according to difference data between the sample data and an ideal sample data;
- and
- a compensating unit which removes the component of the shift in the base line from the data signal to transmit the data signal to the signal processing unit, and
- wherein the decoding unit includes a Viterbi detector which carries out ML type of data detection processing from the sample data, and which further comprises a generator which generates the ideal sample data from a data series detected by the Viterbi detector.
8 more elements
A disk drive using a disk medium in which a plurality of groups of data tracks for recording a data signal is formed by a perpendicular magnetic recording method and each group of data tracks is managed in each plurality of zones, comprising:
- a head to read out a data signal recorded in a disk medium in read operation;
- and
- a read channel to process the data signal outputted from the head by a PRML signal processing method to reproduce recording data,
- wherein the read channel includes:
- a high-pass filter circuit having lower cut-off frequency characteristics;
- a signal processing unit which generates sample data obtained from the data signal outputted from the high-pass filter circuit by a PR type of waveform equalizing processing;
- a decoding unit to decode the recording data from the sample data;
- an extracting unit which extracts a component of a shift in a base line included in the data signal according to difference data between the sample data and an ideal sample data;
- and
- a compensating unit which removes the component of the shift in the base line from the data signal to transmit the data signal to the signal processing unit, and
- wherein the extracting unit includes an integrating circuit and a gain adjusting circuit which have high-frequency cut-off characteristics processing the difference data signal, and which further comprises a parameter adjusting unit which adjusts a gain parameter set in the gain adjusting circuit according to a zone of a read object decided in the read operation.
8 more elements
A disk drive using a disk medium in which a plurality of groups of data tracks for recording a data signal is formed by a perpendicular magnetic recording method and each group of data tracks is managed in each plurality of zones, comprising:
- a head to read out a data signal recorded in a disk medium in read operation;
- and
- a read channel to process the data signal outputted from the head by a PRML signal processing method to reproduce recording data,
- wherein the read channel includes:
- a high-pass filter circuit having lower cut-off frequency characteristics;
- a signal processing unit which generates sample data obtained from the data signal outputted from the high-pass filter circuit by a PR type of waveform equalizing processing;
- a decoding unit to decode the recording data from the sample data;
- an extracting unit which extracts a component of a shift in a base line included in the data signal according to difference data between the sample data and an ideal sample data;
- and
- a compensating unit which removes the component of the shift in the base line from the data signal to transmit the data signal to the signal processing unit, and
- wherein the extracting unit includes a high-frequency cut-off filter which processes the difference data signal, and which further comprises a parameter adjusting unit which adjusts a cut-off parameter of the high-frequency cut-off filter according to a temperature value detected in the read operation.
8 more elements
A disk drive using a disk medium in which a plurality of groups of data tracks for recording a data signal is formed by a perpendicular magnetic recording method and each group of data tracks is managed in each plurality of zones, comprising:
- a head to read out a data signal recorded in a disk medium in read operation;
- and
- a read channel to process the data signal outputted from the head by a PRML signal processing method to reproduce recording data,
- wherein the read channel includes:
- a high-pass filter circuit having lower cut-off frequency characteristics;
- a signal processing unit which generates sample data obtained from the data signal outputted from the high-pass filter circuit by a PR type of waveform equalizing processing;
- a decoding unit to decode the recording data from the sample data;
- an extracting unit which extracts a component of a shift in a base line included in the data signal according to difference data between the sample data and an ideal sample data;
- and
- a compensating unit which removes the component of the shift in the base line from the data signal to transmit the data signal to the signal processing unit, and
- wherein the extracting unit includes a high-frequency cut-off filter and a gain adjusting circuit which process the difference data signal, and which further comprises a parameter adjusting unit which adjusts a cut-off frequency parameter of the high-frequency cut-off filter and a gain parameter set in the gain adjusting circuit according to a temperature value detected in the read operation.
8 more elements
A disk drive using a disk medium in which a plurality of groups of data tracks for recording a data signal is formed by a perpendicular magnetic recording method and each group of data tracks is managed in each plurality of zones, comprising:
- a head to read out a data signal recorded in a disk medium in read operation;
- and
- a read channel to process the data signal outputted from the head by a PRML signal processing method to reproduce recording data,
- wherein the read channel includes:
- a high-pass filter circuit having lower cut-off frequency characteristics;
- a signal processing unit which generates sample data obtained from the data signal outputted from the high-pass filter circuit by a PR type of waveform equalizing processing;
- a decoding unit to decode the recording data from the sample data;
- an extracting unit which extracts a component of a shift in a base line included in the data signal according to difference data between the sample data and an ideal sample data;
- and
- a compensating unit which removes the component of the shift in the base line from the data signal to transmit the data signal to the signal processing unit, and
- wherein the extracting unit includes an integrating circuit and a gain adjusting circuit which have the high-frequency cut-off characteristics processing the difference data signal, and which further comprises a parameter adjusting unit which adjusts a gain parameter set in the gain adjusting circuit according to a temperature value detected in the read operation.
8 more elements
A disk drive using a disk medium in which a plurality of groups of data tracks for recording a data signal is formed by a perpendicular magnetic recording method and each group of data tracks is managed in each plurality of zones, comprising:
- a head to read out a data signal recorded in a disk medium in read operation;
- and
- a read channel to process the data signal outputted from the head by a PRML signal processing method to reproduce recording data,
- wherein the read channel includes:
- a high-pass filter circuit having lower cut-off frequency characteristics;
- a signal processing unit which generates sample data obtained from the data signal outputted from the high-pass filter circuit by a PR type of waveform equalizing processing;
- a decoding unit to decode the recording data from the sample data;
- an extracting unit which extracts a component of a shift in a base line included in the data signal according to difference data between the sample data and an ideal sample data;
- and
- a compensating unit which removes the component of the shift in the base line from the data signal to transmit the data signal to the signal processing unit, and
- wherein the extracting unit includes a high-frequency cut-off filter and a gain adjusting circuit which process the difference data signal, and which further comprises a retry control unit which carries out retry of the read operation in the case that data decoded by the decoding unit is error data in the read operation;
- and a parameter adjusting unit which adjusts a cut-off frequency parameter of the high-frequency cut-off filter and a gain parameter set in the gain adjusting circuit in the retry operation.
9 more elements
A disk drive for perpendicular magnetic recording, comprising:
- a head which reads out a data signal recorded in a disk medium;
- and
- a read channel which includes a signal processing unit having lower cut-off frequency characteristics and including a high-pass filter which carries out removal of low-frequency noise of the data signal outputted from the head and a decoding unit which decodes recording data from the data signal,
- wherein the read channel includes:
- an extracting unit which extracts a component of a shift in a base line of the data signal processed by the signal processing unit, and
- a compensating unit which removes the component of the shift in the base line from the data signal, and
- wherein the extracting unit includes a integrating circuit and a gain adjusting circuit which have the high-frequency cut-off characteristics processing the difference data signal, and which further comprises a retry control unit which carries out retry of the read operation in the case that data decoded by the decoding unit is error data in the read operation;
- and a parameter adjusting unit which adjusts a cut-off frequency parameter of the high-frequency cut-off filter and a gain parameter set in the gain adjusting circuit in the retry operation.
5 more elements
A read channel which is applied to a disk drive using a head to read out a data signal recorded in a disk medium by a perpendicular magnetic recording method and processes the data signal outputted from the head by a PRML signal processing method to reproduce recording data, comprising:
- a high-pass filter having lower cut-off frequency characteristics;
- a signal processing unit which generates sample data obtained from the data signal outputted from the high-pass filter circuit by a PR type of waveform equalizing processing;
- a decoding unit to decode the recording data from the sample data;
- an extracting unit which extracts a component of a shift in a base line included in the data signal according to difference data between the sample data and an ideal sample data, the extracting unit including an integrating circuit or a gain adjusting circuit which has a high-frequency cut-off filter or high-frequency cut-off characteristics and generating a signal corresponding to the component of the shift in the base line;
- a compensating unit to remove the component of the shift in the base line from the data signal to transmit the data signal to the signal processing unit;
- and
- a register to adjust a cut-off frequency parameter of the high-frequency cut-off filter and a gain parameter set in the gain adjusting circuit.
4 more elements
Dependencies are inferred from the claim text.