Samsung Electronics Co., Ltd.

Conner Peripherals, Inc.

Me Van Le

Jong-Ming Lin

William E Wevers

Charles R Nielsen

Charles A Bates

Matthew W Rooke

Fred R Hansen

Thomas Huynh

Eugene K Lew

Paul T Petersen

A method and apparatus for storing position offset information not used for aligning the read element of an MR head with the centerline of written data, during a read operation. The skew or offset between the read and the write elements on a read head is first calibrated. The offset information then stored on one or more dedicated tracks of the disk. To accomplish this, the write element is aligned with the centerline of the dedicated track. The position offset information is then written in the data field of the dedicated track. During the power-on process, the read element is aligned with the centerline of the dedicated track and the position offset information may be retrieved by simply reading the information previously stored on the dedicated track.

Method and apparatus for storing position offset information on a hard drive assembly cylinder

The present invention is a method and apparatus for providing positional information of a disk. The disk has at least one side with a plurality of tracks, each having a first burst in a first servo field and a second burst in a second servo field. The first burst provides a first portion of track position information while the second burst provides a second portion of track position information. When combined, the first and second portions provide a position of a corresponding track. Each track further includes a third and a fourth burst that provides a first portion and a second portion of disk side position information. When combined, the first and second portions of disk side position information provide the disk side position of the disk. Each track also includes a burst that provides the quadrant position of the disk. In one embodiment, the first and second bursts are located on consecutive sectors, and each track includes a servo sector sequence burst with a sector sequence number that identifies the sequence position of the consecutive sectors. The first portion, the second portion and their corresponding sector sequence number in combination provide a position of a corresponding track.

Method and apparatus for providing positional information on a disk

A method and apparatus for generating servo information used in positioning the read head of a hard disk drive. The apparatus comprises a disk having a plurality of tracks, at least one of which has a data field which includes a plurality of servo bits, each of said servo bits being radially offset from an adjacent servo bit by a predetermined amount. In one embodiment, the predetermined amount is 5% of a width of the track. A servo signal based on the plurality of servo bits is generated and used to position the head relative to a track of the disk.

Method and apparatus for providing servo gain linearization for a magneto-resistive head

The present invention is a method and apparatus for generating a skew or position offset signal for aligning the read element of an MR head with the centerline of written data, during a read operation. The disk has a plurality of tracks, one of which contains a calibration burst that allow the read element to be centered with the centerline of written data. This is accomplished by first writing the calibration burst on a predetermined number of sectors of the track. A profile of the calibration burst is obtained by micro-jogging the head from a first position that is -50% from the track centerline to a second position that is +50% of the track centerline, and sensing the magnitude of the calibration burst in various increments between the first and the second positions. For each microjogging position, the magnitude of the calibration burst is obtained. The microjogging position corresponding to the peak value of the calibration burst represents the offset between the read and the write elements. The offset signal is stored in memory and used in a servo routine to center the MR head during a read operation. The calibration burst may be included in a single track, a predetermined number of tracks, or on every track of the disk.

Method and apparatus for providing read and write skew offset

The present invention is a method and apparatus for generating a skew or position offset signal for aligning the read element of an magneto-resistive (MR) head with the centerline of written data, during a read operation. The disk has a plurality of tracks each of which are divided into sectors. Two adjacent tracks are first erased and a calibration burst is written in the odd sectors, for example, the first and third sectors of one of the tracks. A calibration burst is also written in the even sectors, such as the second and fourth sectors of the adjacent track. Without adjusting the position of the MR head, the value of the calibration burst on the latter track is read. Since the read element is offset from the write element, it can read the values of the calibration bursts on the odd sectors of one track and the values of the calibration bursts on the even sectors of the other track. The average values of calibration bursts, E.sub.oddave and E.sub.evenave are obtained. An offset value corresponding to E.sub.oddave -E.sub.evenave =0 is obtained and an offset signal corresponding to this offset value is generated. A servo operation is then performed to align the center of the read element with the centerline of the written data. Alternatively, the value of the calibration burst E.sub.odd in the first odd sector, and the value of the calibration burst E.sub.even may be read to obtain an offset value corresponding to E.sub.odd -E.sub.even =0.

The present invention is a method and apparatus for rewriting servo information on a disk of a hard disk drive. The new servo pattern is written on the tracks on the heads or sides of a disk pack using the stagger wedge scheme. When the read/write heads reach the first track beyond the inner diameter crash stop of the disk pack, the first read/write head is directed to write the new servo information, followed by the writing of data in each sector of the entire track, while the other read/write heads remain deactivated. The data writes over any pre-existing servo information on the track. Next, the second read/write head is directed to write the new servo information, followed by the writing of data in each sector of a complete track while the other read/write heads are deactivated. During the power-on sequence, the read/write heads are directed to the portions of the disk beyond the inner diameter crash stop, where the new servo pattern and the new data have been written, so as to read the new servo pattern.

Method and apparatus for rewriting servo information on a disk in a hard

Method and apparatus for storing position offset information on a hard

A method and apparatus for generating servo information used in positioning the read head of a hard disk drive. The apparatus comprises a disk having a plurality of tracks, at least one of which has a servo field which includes four servo bits: an A bit, a B bit, a C bit and a D bit, where the A bit and the B bit have a common boundary located at the track centerline and where the C bit and the D bit have a common boundary. A servo signal based on the four servo bits is generated and used to position the head relative to a track of the disk. A servo signal may be generated from the sum of the difference between the A and B bits, and the difference between the C and D bits. An offset may be used to eliminate phase errors introduced into the servo signal. The offset may be representative of the magnitude of the difference between the C and D bits. The servo signal may also be generated from the difference of the difference between the A and B bits, and the difference between the C and D bits.

Method and apparatus for generating servo information

A write drive logic circuit is described. The write driver logic circuit comprises a set of write drivers, with each one of the set of write drivers having an input and an output, such that each write driver is responsive to an input signal applied to the input to provide a write output signal at the output as a function of the input signal. A set of memory devices (e.g. shift registers) is provided, one for each write driver. Each one of the shift registers stores unique head identification information and includes an output to controllably output a signal representative of the unique head identification information. Furthermore, each one of a set of multiplexers includes an output, a first input coupled to a corresponding one of the outputs of the set of shift registers to receive the signal representative of the unique identification information stored in the respective shift register and a second input coupled to a common write data line that transmits a signal representative of preselected information. The output of each one of the set of multiplexers is coupled to the input of a corresponding one of the set of write drivers such that one of the first and second inputs of the multiplexer is selectively applied to the input of the corresponding write driver.

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Milpitas, CA, United States of America

Me Van Le