Western Digital Technologies, Inc.

Western Digital Corporation

David Price Turner

Robert L Cloke

Vafa James Rakshani

Richard William Hull

Gary L Dunbar

Jack M Chue

Michael R Spaur

Robert Ellis Caddy, Jr

Mohamad Towfik Krounbi

Brian Kenneth Tanner

John Cuda

Hanan Kupferman

Yoo H Kim

William C Tipton, Ii

A method of selecting a track density for a disk surface of a disk drive is disclosed. A first pattern is written along a circumferential path of the disk surface, wherein the first circumferential path comprise a first set of arcuate sections interleaved with a second set of arcuate sections. A second pattern is written radially offset from the circumferential path during time intervals corresponding to the first set of arcuate sections. The head is positioned substantially over the center of the first circumferential path and during time intervals corresponding to the second set of arcuate sections, the first pattern is read to generate a first read signal amplitude measurement A, and during time intervals corresponding to the first set of arcuate sections, the first pattern is read to generate a second read signal amplitude measurement A. A track density is selected in response to Aand A, wherein the track density is for use in writing embedded servo sectors to the disk surface.

Selecting a track density for each disk surface of a disk drive based on head characteristic

A preamplifier circuit is disclosed comprising a data input for receiving write data, a read signal output for outputting an amplified read signal, a read signal input for receiving a read signal from a read element, and a write signal output for supplying a write signal to a write element. The preamplifier circuit further comprises a first amplifier circuit, responsive to the write data, for generating the write signal supplied to the write element, and a second amplifier circuit for amplifying the read signal from the read element to generate the amplified read signal output via the read signal output. A head control circuit, responsive to head select data, simultaneously enables the first and second amplifier circuits to perform a simultaneous read and write operation.

Preamplifier circuit configurable to allow simultaneous read and write operations for self-servo writing a disk drive

The present invention may be regarded as a self-servo writing disk drive comprising a head having a read element radially offset from a write element. During a first time interval, the read element is positioned over a first radial location to read first A clock data to generate first circumferential timing information and first A servo bursts to generate first position control information. The first position control information is used for positioning the write element over a second radial location, and the first circumferential timing information is used for writing second B clock data and second B servo bursts to the second radial location. During a second time interval, the read element is positioned over the first radial location to read first B clock data to generate second circumferential timing information and first B servo bursts to generate second position control information. The second position control information is used for positioning the write element over the second radial location, and the second circumferential timing information is used for writing second A clock data and second A servo bursts to the second radial location.

Self-servo writing a disk drive by propagating interleaved sets of timing clocks and servo bursts during alternate time intervals

A method of calibrating a write current-setting for writing servo sectors onto a recording surface through a head in a head disk assembly of a disk drive is disclosed. A preamplifier circuit has an input for receiving a selected control signal set by a current-setting value, the preamplifier circuit causing current to flow through the head with a current magnitude determined by the current-setting value. A multiple-pass process is performed in which a series of current-setting values are set for the control signal for generating a plurality of quality metrics each indicative of a quality of the selected control signal. Each pass in the multiple-pass process includes the steps of providing a data sequence to the preamplifier circuit to cause a test pattern to be written to the recording surface, and reading the test pattern and generating and storing at least one of the plurality of quality metrics. The generated and stored quality metrics are then evaluated to select a current-setting value for the selected control signal. The selected current-setting value is then set for the head, and the servo sectors are written onto the recording surface through the head.

Method of calibrating a write current-setting for servo writing a disk drive

A computer system is disclosed comprising a host connected to a disk drive, the disk drive comprising a disk having a disk surface. The disk drive further includes a controller and a channel integrated circuit chip. The controller includes a controller port. The channel integrated circuit chip includes an input for receiving a time-multiplexed analog read signal. The time-multiplexed analog read signal is processed to generate data symbols representing recovered servo data and recovered user data. The channel integrated circuit chip includes a channel port for transferring both the recovered servo data and the recovered user data. The disk drive further includes a communication bus connected between the channel port and the controller port. The channel port transfers both the recovered servo data and the recovered user data to the communication bus. The communication bus transfers both the recovered servo data and the recovered user data to the controller port.

Computer system comprising a host connected to a disk drive employing read channel IC with common port for data and servo

A computer system is disclosed comprising a host connected to a disk drive, the disk drive comprising a disk surface having a plurality of tracks arranged in an embedded servo format including servo track segments for storing servo data and data track segments for storing user data. The disk drive includes a read element operative during a user-data read operation for reading data from the disk surface to produce a time-multiplexed analog read signal that during a revolution of the disk represents analog read servo data during each of a first set of time intervals and represents analog read user data during each of a second set of time intervals. The disk drive includes a sampled signal processing circuit that generates a servo state variable while processing the time-multiplexed read signal during the first servo time interval and a user data state variable while processing the time-multiplexed read signal during the first user data time interval. The disk drive includes a servo state variable trap register for storing the servo state variable at the end of the first servo time interval. The disk drive includes a data state variable trap register for storing the user data state variable at the end of the first user data time interval. The disk drive includes a control circuit for providing the stored servo state variable to the sampled signal processing circuit at the beginning of the second servo time interval. The control circuit provides the stored user data state variable to the sampled signal processing circuit at the beginning of the second user data time interval.

Computer system comprising a host connected to a disk drive employing state variable trap registers for providing stored servo and user data state variables to sampled-data channel

A disk drive includes a disk having a disk surface, the disk surface having a plurality of tracks arranged in an embedded servo format. The disk surface includes a plurality of radially-extending user-data regions and a plurality of radially-extending servo-data regions. Each user-data region has a plurality of data zones in each of which user data are stored in a plurality of track segments at a data channel frequency particular to that data zone. Each servo-data region has a plurality of servo zones in each of which servo data are stored in a plurality of track segments at a servo channel frequency particular to that servo zone, wherein in at least one of the tracks having servo data and user data, the servo channel frequency differs from the data channel frequency.

Disk drive including a recording surface employing servo zones recorded at a channel frequency different from data zones

A disk drive comprising a plurality of recording surfaces and plurality of associated heads is disclosed employing a n-current preamplifier for generating n independently controlled write currents. For example, the n-current preamplifier may be employed during manufacturing of the disk drive to simultaneously write servo sectors to all of the recording surfaces in a &ldquo;bank servo write&rdquo; mode. The n-current preamplifier comprises an input for receiving a plurality of current-setting control signals corresponding to the plurality of heads, and a plurality of signal-to-current converters for converting the current-setting control signals into a plurality of write currents for the heads, wherein each write current has a magnitude that is independently controlled by a respective one of the current-setting control signals. The optimal write current for each head is determined during a calibration mode wherein a test pattern is written to and read from the disk to generate a quality metric indicative of the quality of the write current setting. Several write current settings are tested for each head, and the write current that generates the best quality metric for each head is used to simultaneously write the servo sectors to the recording surfaces.

Disk drive including N-current preamplifier for generating N-independently controlled write currents

A disk drive includes a disk having a disk surface. The disk surface has a plurality of tracks arranged in an embedded servo format including servo track segments for storing servo data and data track segments for storing user data. Data from the disk surface is read to produce a time-multiplexed analog read signal that during a revolution of the disk represents analog read servo data during each of a first set of time intervals and represents analog read user data during each of a second set of time intervals. The disk drive further includes a controller and a channel integrated circuit chip. The controller includes a controller port. The channel integrated circuit chip includes an input for receiving the time-multiplexed analog read signal. The time-multiplexed analog read signal is processed to generate data symbols representing recovered servo data and recovered user data. The channel integrated circuit chip includes a channel port for transferring both the recovered servo data and the recovered user data. The disk drive further includes a communication bus connected between the channel port and the controller port. The channel port transfers both the recovered servo data and the recovered user data to the communication bus. The communication bus transfers both the recovered servo data and the recovered user data to the controller port.

Disk drive employing read channel IC with common port for data and servo

A disk drive includes a disk having a disk surface, the disk surface having a plurality of tracks arranged in an embedded servo format. The disk surface includes a plurality of radially-extending user-data regions and a plurality of radially-extending servo-data regions. Each user-data region has a plurality of data zones in each of which user data are stored in a plurality of track segments at a data channel frequency particular to that data zone. Each servo-data region has a plurality of servo zones in each of which servo data are stored in a plurality of track segments at a servo channel frequency particular to that servo zone. The servo channel frequency differs from the data channel frequency for at least one track.

Disk drive including a recording surface employing servo zones with banded data zones

A system for polling a preamplifier unit to remotely determine pre-established parametric values in a disk drive is disclosed. The disk drive comprises a controller, a preamplifier, and a plurality of transducers. The system for polling the preamplifier comprises means in the controller for generating a succession of serial bit characters each representative of a different pattern. A means is provided for successively transferring said serial bit characters from the controller to the preamplifier unit. A plurality of individual bit lines are provided in the preamplifier unit representative of at least one parametric value. A means is included in the preamplifier unit for comparing each serial bit pattern character received with said plurality of individual bit lines, and for generating a match signal when a serial bit pattern character received matches the plurality of individual bit lines. A means is provided for transferring the match signal from the preamplifier unit to the controller.

Polling a preamplifier within a disk drive to remotely determine pre-established parametric values

A disk drive includes a disk surface having a plurality of tracks arranged in an embedded servo format including servo track segments for storing servo data and data track segments for storing user data. The disk drive includes a read element operative during a user-data read operation for reading data from the disk surface to produce a time-multiplexed analog read signal that during a revolution of the disk represents analog read servo data during each of a first set of time intervals and represents analog read user data during each of a second set of time intervals. The disk drive includes a sampled signal processing circuit that generates a servo state variable while processing the time-multiplexed read signal during the first servo time interval and a user data state variable while processing the time-multiplexed read signal during the first user data time interval. The disk drive includes a servo state variable trap register for storing the servo state variable at the end of the first servo time interval. The disk drive includes a data state variable trap register for storing the user data state variable at the end of the first user data time interval. The disk drive includes a control circuit for providing the stored servo state variable to the sampled signal processing circuit at the beginning of the second servo time interval. The control circuit provides the stored user data state variable to the sampled signal processing circuit at the beginning of the second user data time interval.

Disk drive employing state variable trap registers for providing stored servo and user data state variables to sampled-data channel

A disk drive comprising a plurality of read/write transducers, a programmable preamplifier, and a controller for furnishing control and data signals to the programmable preamplifier and for receiving data signals therefrom, is disclosed. The programmable preamplifier comprising a write data input circuit for receiving data signals to be supplied to a transducer, a read data output circuit for manifesting data signals supplied to said preamplifier unit by a transducer, and a transducer interface circuit for providing write data signals to a transducer and receiving read data signals from a transducer. The programmable preamplifier further comprises a multiplexer comprising a first multiplexer input connected to receive a first internal digital signal, a second multiplexer input connected to receive a second internal digital signal, a control input connected to receive a control signal for selecting between the first and second internal digital signals, and a multiplexer output for outputting the selected first or second internal digital signal. The multiplexer output is connected to an output terminal of the programmable preamplifier. The programmable preamplifier comprises a serial interface circuit for receiving serially presented control signals from the associated controller, including the control signal for selecting between the first and second internal digital signals.

Disk drive comprising a programmable preamplifier including a

A disk drive preamplifier unit includes a serial interface circuit for receiving serially formatted control signals from an associated disk drive controller. The control signals contain several types of information, including head select, write current magnitude, bias for MR transducers, gain magnitude for a variable gain amplifier, and test and mode information. The preamplifier unit incorporates several test circuits in addition to the usual write unsafe detector circuit, and a multiplexer controlled by the mode control signals from the serial interface unit is used to select which test circuit or detector is coupled to a common test output terminal whose signals are coupled back to the controller for further processing. The preamplifier can be used to remotely test the head population of the head disk assembly, to measure the MR bias current through any of the MR transducers and to signal the controller in response to polling characters when a match is obtained between a character and preestablished multi-bit parameter information fixed in the preamplifier unit. A write current generator is shared by the write transducers and the MR bias test circuit, with a current scaling unit used to provide different current ranges from the common source. The preamplifier unit affords remote control and testing which can be adapted to evolving systems using firmware changes alone.

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Los Gatos, CA, United States of America

David Price Turner