Abstract: An apparatus and method for compensating repeated runout position error in a disc drive data handling system having an actuator assembly which supports a head adjacent a recording surface. A servo loop generates a position error signal (PES) to control the position of the head. A digital filter is configured to place a notch in an error sensitivity function relating the PES to the repeated runout position error, with the notch being nominally centered at a frequency of rotation of the recording surface. The filter thereafter filters the PES to generate compensation signals that are injected into the servo loop. At least selected filter parameters are determined by measuring the frequency response of the servo loop and used as a priori knowledge to produce a loop matching effect that results in a consistent convergence rate for any targeted frequency to be filtered.

Abstract: A method and apparatus are provided for positioning a head based on a control signal and a cancellation signal. In the method and apparatus, a sensor located in the disc drive is capable of generating sensor data samples at a sensor data rate that is different from a servo data rate. A data enlarger inserts additional data samples between the sensor data samples to produce enlarged data that is filtered to produce filtered data, which is decimated to form decimated sensor data at the servo data rate. A cancellation component converts the decimated sensor data into a cancellation signal that may be combined with a control signal to control the actuator. A sensor chip is also provided that includes a sensing element and a sigma-delta circuit that cooperate to generate sensor samples at a sensor data rate and a buffer that stores sensor samples at the sensor data rate.

Abstract: In a large-capacity FD comprising a disk-shaped recording medium on which a plurality of tracks are arranged with concentric circles, each track is divided into a predetermined number of sectors having a length equal to one another. Each sector consists of a serve field and a data field. The servo field in each sector includes a sector number field in which a sector number and alternation contents of the magnetic disk medium are written and a track number field in which a track number is written. The sectors on each track may be assigned with serial sector numbers in a circumferential direction in order with skipping over any defective sector. The plurality of tracks may be separated in a radial direction into a plurality of zones each including at least one alternate track.

Abstract: In a servo area SA on a track that is empty of data and that lies outside a user data read/write area, to and from which a user data of a floppy disc is written and read, format information FI of the floppy disc is recorded. The format information FI is recorded along with a track number TN in a gray code area GA in the servo area SA. Thereby, the format of the floppy disc can be identified with no identification hole or the like formed in an envelope encasing the floppy disc.

Abstract: A servo burst signal recording method using an enhanced pattern and a disk recording medium are provided. The disk recording medium having at least two servo burst regions on which servo burst signals are recorded in the diametrical direction on tracks of the disk recording medium, the servo burst regions each being divided into at least two sub-regions in a traveling direction of a head, one sub-region having the same width as that of a track, and the other sub-region having a smaller width than that of the track. The disk recording medium enables the user to obtain a servo burst signal component without having a dead zone even in the case when the width of a reading head is smaller than that of the recording head, which enhances the accuracy of the tracking control.

Abstract: A highly reliable, low overhead method for determining a position of a magnetic storage medium that is divided into a plurality of servo sections is provided. The inventive method includes defining a predetermined bit pattern that corresponds to a known position of the magnetic storage medium. A positional index bit is associated with each servo section such that a known bit of the predetermined bit pattern is associated with the known position of the magnetic storage medium. A current positional index bit is read from the magnetic storage medium and a positional bit sequence comprising the current positional index bit is formed. The positional bit sequence is compared with the predetermined bit pattern and, based on the comparison, whether the position of the magnetic medium is the known position can be determined.

Abstract: An information storage apparatus has a disk medium setting data recording areas along a plurality of tracks concentrically arranged, a head for recording and reproducing data on tracks of the disk medium, an actuator for moving the head to a desired track among the plurality of tracks. Also included is an electric circuit for controlling recording and reproducing in response to detecting the distance from a recorded magnetization pattern on an adjacent track in the radial direction by detecting previously recorded signals on adjacent tracks while data recording. Even if the track density is increased, the upper limit of a threshold value of a function for preventing off-track recording of the information storage apparatus can be increased and a high track density of the information storage apparatus can be easily realized.

Abstract: A digital servo system for a disk drive provides servo information signal demodulation. The system includes a digital demodulator including a burst signal accumulator that accumulates terms according to respective burst timing intervals to produce a digital, quadrature position error signal (PES). The demodulator also can include a dibit burst filter with synchronous dibit sampling preferably implemented as a Hilbert Transform filter. Alternatively, the demodulator does not include a filter and a squarer and, instead, the squarer comprises a sum-and-squarer that sums the squares of odd and even digitized samples. In another embodiment, the system employs a digital demodulator having a digital squarer that removes any phase component of the digitized servo information signal and includes a burst signal accumulator that accumulates the squared terms according to respective burst timing intervals to produce the PES. The demodulator may include a filter comprising a harmonic notch filter.

Abstract: A method and apparatus for compensating for repeatable run-out errors in a disc drive is provided in which transfer function values for a servo loop in the disc drive are first determined. A sequence of repeatable run-out values for a portion of the disc drive is then determined. A transform is applied to the sequence of repeatable run-out values to obtain frequency-domain repeatable run-out values. Each frequency-domain repeatable run-out value is divided by a respective transfer function value to produce a sequence of frequency-domain compensation values which are then stored. An inverse transform is applied to the frequency-domain compensation values to obtain a sequence of time-domain compensation values. The sequence of time-domain compensation values is inserted into the servo loop.

Abstract: A highly reliable, low overhead method for determining a rotational position of a magnetic storage medium that is divided into a plurality of servo sections is provided. The inventive method includes defining a predetermined bit pattern that corresponds to a known position of the magnetic storage medium. A rotational position indicator bit is associated with each servo sector such that a known bit of the predetermined bit pattern is associated with the known position of the magnetic storage medium. A current rotational position indicator bit is read from the magnetic storage medium and a rotational position bit sequence comprising the current rotational position indicator bit is formed. The rotational position bit sequence is compared with the predetermined bit pattern and, based on the comparison, whether the rotational position of the magnetic medium is the known rotational position can be determined.

Abstract: A disk drive having a rotary actuator, an embedded servo system for controlling the rotary actuator, a rotating disk surface for recording and reproducing data, and a dual element head supported by the actuator comprising a read element and a write element. The disk surface has a plurality of repeating servo track patterns defining radially spaced-apart servo tracks. The disk surface further includes a user data band having a plurality of radially spaced-apart data tracks for storing user data. Each data track is written with an offset from a corresponding servo track centerline depending on a skew introduced by the dual element head. A reserved band is located outside the user data portion including a reserved data track for storing drive specific data wherein the reserved data track is centrally aligned with a corresponding servo track centerline. The reserved data track can be read reliably by the read element when the servo system is tracking on the servo track centerline.

Abstract: The invention provides a high-speed interface that transfers user data and other data over a single unified interface between a read channel integrated circuit and another integrated circuit, such as the drive control integrated circuit. The high-speed interface eliminates the need for analog pins on the integrated circuits to lower the cost of the system. The high-speed interface also eliminates the use of the serial interface to transfer the servo position data and other data which speeds up the data transfer. Examples of the other data include read channel settings, read channel performance data, and servo data. A read channel integrated circuit exchanges the user data with a data bus when the disk drive system is reading or writing the user data. The read channel integrated circuit exchanges the other data with the data bus when the disk drive system is reading servo data. The other integrated circuit exchanges the user data with the data bus when the disk drive system is reading or writing the user data.

Abstract: An apparatus and method for correcting static track spacing errors in a data storage device having a plurality of concentric servo tracks. The data storage device includes a disc having a plurality of concentric servo tracks, an actuator assembly including a head adjacent the disc, and a controller operable for controlling the position of the head relative to the disc and operable to determine a correction factor indicative of a static track spacing error between servo tracks. The correction factor is used during operation of the data storage device to generate a corrected position signal for use by the data storage device in positioning the head with respect to the disc.

Abstract: The present invention proposes a new servo track writing technique called Extended Copying with Head Offset (“ECHO”). The read and write elements of the read/write head are offset from each other. A servo writer writes a guide pattern on the magnetic media disc. ZAP correction factors are added to the guide pattern. The head disc assembly is then connected to an electrical control system for self-propagating servo writing. The actuator arm is displaced until the read head is aligned over the guide pattern. A new servo track is written by the write element. ZAP correction factors are added to the newly written servo track. The actuator arm is displaced until the read element is aligned with the newly written servo track. A new servo track is written. ZAP correction factors are added to the newly written servo track. The process is repeated until a desired number of servo tracks are written.

Abstract: In a disk drive system, a servo controller is operative to perform a process of inhibiting write operations for writing data to tracks of a disk during a head settling period following a track seek operation. During each of a first plurality of sampling intervals transpiring during a first time period, the servo controller determines a present position value indicative of the position of the head during the present sampling interval, and also determines a predicted position value indicative of the position of the head during a subsequent sampling interval. Also during each of the first plurality of sampling intervals, the servo controller determines: whether the present position value is within a first error margin from the center of a target track; and whether the predicted position value is within the first error margin. If the present position value and the predicted position value are both within the first error margin, the servo controller enables write operations.

Abstract: A disk device, track positioning method, and method for generating a position error signal in which the occurrence of a wrong correction operation can be prevented by creating an appropriate PES without using a burst pattern having a defect, and reassign sectors can be decreased by decreasing defective sectors thereby to reduce the performance degradation is disclosed. In the disk device and track positioning method, the defect of a burst pattern read out from a disk is detected, and if a defect is detected in the burst pattern, a data value corresponding to the sum data of the burst pattern pair having the defect detected is obtained by measuring the maximum amplitude value of the burst pattern pairing with the burst pattern having the defect detected, and a PES is created according to the amplitude of the burst pattern having the defect detected and the maximum amplitude value.

Abstract: The present invention is a method of correcting radial position error signal (PES) values by utilizing predetermined error correction values located at predetermined locations in advance of their associated servo fields. Calculated correction values are written to zero-acceleration path (ZAP) fields on the disc during the manufacture process. ZAP fields are positioned before the servo fields whose PES they are designed to correct. The ZAP field is comprised of two or more correction data elements to correct subsequent PES values. As the read/write head flies along a track, it reads a ZAP field, and stores the PES correction data in local random access memory (RAM). Subsequently, the corresponding servo field is read and the stored PES correction data is used to correct the PES. Two types of ZAP fields are written on the disc—one type for read operations, another type for write operations.

Abstract: Marks with curved edges are used in data patterns and sensed with proximity recording. Circular, elliptical, and oval marks are examples of marks with curved edges that can be used in the present invention. The marks with curved edges are used to define data patterns (e.g. position error signal patterns) as a function of radius. If the marks with curved edges have been recorded longitudinally, an amplitude of a read back signal, such as a peak amplitude, is determined in order to generate a position error signal. If the marks with curved edges have been recorded vertically, an area under the curve of the read back signal is determined in order to generate a position error signal.

Abstract: A recording disk has a data area and a servo-burst area alternately arranged with each other in the circumferential direction of the disk. The servo-burst area has a servo-burst pattern having signal sections and non-signal sections arranged with a period &lgr; in the radial direction of the disk. The period &lgr; is expressed by &lgr;=2p×n/m in terms of track pitch “p” of the disk, wherein n and m are integers prime to each other provided that n/m<2.

Abstract: An apparatus and method of reducing the size of a servo burst and thus increasing the disc surface available for data storage is accomplished by uniquely encoding track information in the gray code of a servo burst on a disc. Each track has a unique sequential track identification number assigned to it. A plurality of sets of servo sectors on each track are encoded with a modulo operation of the track identification number for the track each using a unique modulus. Preferably the sectors are grouped into two sets, i.e., even numbered sectors on each track are modulo encoded with a first modulo operation of the track identification number for the track using a first modulus and odd numbered servo sectors on each track are modulo encoded with a second modulo operation of the track identification number for the track using a second modulus. Decoding the absolute track address is accomplished by decoding the modulo numbers and comparing the even sector modulo numbers to the odd numbered sector modulo numbers.

Abstract: When a pin layer magnetic field offset judgment unit judges that a magnetic field in a pin layer of a spin valve head through which a sense current flows in the interference direction has been deviated from a normal direction, a recovery processing unit allows a recovery from the abnormality arising from the magnetic field offset. For example, the direction of the sense current is switched from the interference direction to the assist direction, and the sense current larger than that upon the ordinary reading action is allowed to flow so that the temperature of an antiferromagnetic layer exceeds the blocking temperature, whereby the direction of the magnetic field in the pin layer is modified to the normal direction by the action of a magnetic field generated from the sense current. After the modification, the sense current is returned to have its ordinary value in the interference direction.

Abstract: A data recording and/or reproducing apparatus which scans a head over a disc on which a servo pattern for moving the head to a predetermined position is recorded in an arc forming a part of a concentric circle. The apparatus comprises a track No. detector and fine signal detector, for detection of the servo pattern, a circumferential position detector to detect a circumferential position on the disc, an offset calculator to calculate an offset of a current position on the disc from the detected circumferential position, and a positional difference calculator. The calculated offset of the current position is added to the positioning signal to control the head scanning orbit on the disc to be spiral.

Abstract: A method to enable servo information to be detected surely and stably even when a time interval between servo sectors is changed due to disk shifting is provided. A time interval TS(i) is calculated according to an internal variable value, which is in proportion to a displacement &Dgr;r(i) of a servo area SF(i) in a radial direction of a subject disk (step S6). The displacement &Dgr;r(i) is calculated from already detected servo information, thereby a time interval for detecting servo information is adjusted according to the above-described time interval TS(i) (steps S7 and S4). The time interval TS(i) is the time interval between passing of a servo sector in the servo area SF(i) under the head H and passing of a servo sector in the servo area SF(i+1) under the head H.

Abstract: A magnetic recording disk drive has head positioning servo sectors with servo sector numbers (SSNs) that are not recorded on the disk. The SSNs are encoded through the use of multiple servo sector types that are arranged in a specific sequence around the data tracks. The different servo sector types are identified by unique types of servo timing marks (STMs), which are used to locate the servo sectors. The SSNs that are used to identify the servo sectors on the track form a set or code of m fixed n-bit patterns. A SSN is determined when the STM types read from n sequential servo sectors match one of the fixed SSN pattems. A set or code of m servo sectors, where each servo sector is identified by a unique SSN pattern having length n, is denoted as an (m,n,d) code, where d is referred to as the minimum Hamming distance of the code. The Hamming distance between two patterns refers to the number of locations that are different between the two pattems.

Abstract: A disk drive includes a disk having data tracks including servo sectors and data regions disposed between the servo sectors. A transducer head writes data to and reads data from the data regions and reads servo information from the servo sectors. A spindle motor rotates the disk. A spindle motor driver provides current to the spindle motor. A track-following controller is responsive to the servo information for causing the transducer head to remain on track. A microprocessor performs a power-saving idle operation of causing the spindle motor driver to sequentially (1) provide no current to the spindle motor for at least one disk revolution and (2) provide current to the spindle motor for at least one disk revolution. The power-saving idle operation is performed while the track-following controller causes the transducer head to remain on track for multiple disk revolutions.

Abstract: 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.

Abstract: A method and apparatus for writing a servo signal for controlling the position of a head on a disk during the manufacture of a hard disk drive. The present invention provides a method and apparatus for writing servo information on a magnetic disk through a magnetic head by driving an actuator of a hard disk drive (HDD) directly without employing a servo writer using control of a laser. Furthermore, when there is need for increasing the density in tracks per inch (TPI) to obtain a high capacity HDD, HDD manufacturers do not have to produce a new servo writer, thereby reducing production cost.

Abstract: A magnetic storage system having one or more rotating disks is disclosed. In a preferred embodiment, each rotating disk has two magnetic surfaces which each contain a number of tracks. Each track has one or more data regions and one or more embedded servo sectors. First and second transducers are respectively suspended over first and second tracks corresponding to first and second magnetic surfaces. The second transducer determines an off-track position with respect to the second track by reading from the data region of the second track. Once the off-track position is determined for the second transducer, that information is used to position the first transducer with respect to the first track and position the second transducer with respect to the second track as the first transducer writes to the first track. Furthermore, the first transducer is positioned at a correction rate that exceeds the rate at which the first transducer encounters embedded servo sectors in the first track.

Abstract: The present invention is a method and apparatus for providing servo information on a disk in a hard disk drive. The hard disk drive has a disk with a plurality of tracks. Each of the plurality of tracks having at least one servo sector having a first half track portion and a second half track portion. A first location of the first half track portion of the at least one servo sector is erased using a first predetermined field. A second location of the first half track portion that is adjacent to the first half track portion of the at least one servo sector is erased using a second predetermined field. Various embodiments are disclosed.

Abstract: A magnetic disk apparatus includes head bases placed one on another and supported for pivotal motion on a common pivot shaft, and sliders provided at free ends of the head bases and having magnetic heads mounted thereon with suspensions interposed therebetween, respectively. A coil for a voice coil motor serving as a first driving apparatus is provided on the opposite side to the sliders with respect to the pivot shaft. Second driving apparatus formed from piezoelectric elements and hinges are provided between the pivot shaft and the sliders. For faces of a plurality of magnetic disks, recording and/or reproduction operations can be performed simultaneously by integral tracking control of the sliders by the first driving apparatus and individual tracking control of the sliders by the second driving apparatus.

Abstract: 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.

Abstract: A disk drive system having a disk used to store information is disclosed. In one embodiment, the disk includes a servo track having a servo track pitch and a data track having a data track pitch. The servo track pitch and the data track pitch are unequal to one another. A method of reading data from a disk is also disclosed. The method includes the steps of: (1) providing a plurality of servo tracks, each having a track number; (2) providing a plurality of data tracks each having a data track number, wherein the number of servo tracks within a particular region of a disk are related to the number of data tracks within the particular region by a ratio defined as a TPI scale factor; (3) obtaining instructions from a host to read from a particular data track number; and (4) determining which servo track number should be used to access the particular data track.

Abstract: An asynchronous demodulator and method is provided which determines a position error of a read head relative to a position on a medium in a storage device. The read head generates a read signal as the read head passes over a servo area on the medium. The demodulator generates a normal demodulating signal that is asynchronous with the read signal and a quadrature demodulating signal that is ninety degrees out of phase with the normal demodulating signal. The read signal is sampled to produce a series of digital read values which are multiplied by the normal demodulating signal and the quadrature demodulating signal to produce a plurality of normal and quadrature sample values. The demodulator produces the a position error magnitude and a position error direction based on the plurality of normal and quadrature sample values.

Abstract: A disk drive has a sampled servo system controller and a disk with a plurality of angularly spaced servo wedges. Each of the servo wedges contains angularly aligned servo burst fields that are radially adjacent to one another and spaced apart by an erase field. In order to eliminate or minimize servo position signal errors caused by a wide-reading transducer head encountering signals from both of a pair of angularly aligned servo burst fields, the servo burst fields are recorded in opposing phase.

Abstract: A magnetic disk device that has a sufficient tracking control capability and a sufficient capability, and has the rotational speed of a magnetic disk reduced to record moving-image information. A magnetic disk device accesses a magnetic disk with a magnetic head by effecting tracking control of the magnetic disk at predetermined angular intervals, each of the servo areas being formed in synchronism with a clock signal and having a reference pattern for the tracking control. The clock signal is generated by referring to a playback signal from a number of servo areas. Thus, a clock area in one servo can be shortened. The recording density of the magnetic disk is prevented from being reduced even if a number of servo areas area formed on the magnetic disk are effective to prevent the sampling frequency from being lowered. As a result, a sufficient tracking control capability and a sufficient recordable density can be achieved, and the speed of the magnetic disk can be reduced to record moving-image information.

Abstract: High-accuracy position signals are obtained by correcting nonlinear position sensitivities of two phase signals demodulated from two-phase servo information, into linear ones. A position sensitivity adjusting unit detects the signal level at the intersection of position signals N and Q having different phases by a predetermined track pitch which are demodulated from read signals of two-phase servo information buried and recorded in a disk medium and makes an adjustment of the gain of an AGC amplifier so that the intersection signal level coincides with a predetermined level. A sensitivity correcting unit corrects into linear position sensitivities the nonlinear position sensitivities approximated by sine functions or cosine functions relative to the actual track position X of the two position signals N and Q output from the AGC amplifier.

Abstract: A disk type recording and reproducing apparatus includes a disk type recording medium having a plurality of tracks and having stored on each of the plurality of tracks a position signal indicating positions on the tracks; a drive section for rotating the disk type recording medium; a dual head separately incorporating a reading head for reading from the disk type recording medium and a writing head for writing into the disk type recording medium; a head drive section for moving the dual head; means for controlling the head drive section by a controlled variable in compliance with a position signal read from the disk type recording medium using an object track and the reading head; and memory means for storing quantity information used to correct the controlled variable of the means for controlling the head drive section.

Abstract: A method of determining the subtrack within zone P on a recording medium is provided. The recording medium has a plurality of zones 1 through Q. Each zone has a plurality of subtracks 0 through M. Each subtrack has a plurality of sectors 0 through N. Each sector has a position identifier field. Each position identifier field has a plurality of information units for recording a position identifier. The position identifier for Jth sector of subtrack I is identified as S(I,J). A preferred method comprises obtaining the local subtrack value as S(I,0), a space-efficient way to store and extract subtrack location information.

Abstract: A technique for formatting a magnetic disk for a removable magnetic cartridge includes the steps of providing the magnetic disk having a top surface and a bottom surface, writing a first servo track onto the top surface, the first servo track having a portion including a first gray code, a first position burst, and a second position burst, writing a second servo track onto the top surface adjacent to the first servo track, the second servo track having a portion including a second gray code, the second position burst, and a third position burst, and writing a third servo track onto the top surface adjacent to the second servo track, the third servo track having a portion including the second gray code, the third position burst and a fourth position burst, wherein a first data track comprises the first servo track, the second servo track and the third servo track.

Abstract: A phase modulated servo method and apparatus provide acceptable position linearity for servo positioning with a narrow transducer head in a disk file. The disk file includes at least one disk mounted for rotation about an axis and the disk has at least one disk surface for storing data and has at least one transducer mounted for movement across the disk surface for writing to and for reading data and servo patterns from the disk surface. The transducer includes a read element and a write element. The read element has a width less than the write element and the read element width is greater than ⅓ of a data cylinder and less than ½ of a data cylinder. A servo pattern is written on the data disk surface having a track pitch of less than ½ of a data cylinder and the servo pattern repeats in a selected binary number of data cylinders.

Abstract: A direct access storage device that (DASD) includes a sector servo control system that controls disk write operations by receiving a servo pattern readback signal in a sector, determining track centering for that sector, and generating a write inhibit signal before any write operations are initiated for that sector. The servo control system is able to make write inhibit decisions without software processing delays, enabling the system to produce a write inhibit signal quickly after an off-track excursion, and to terminate a write inhibit decision quickly after it is no longer needed.

Abstract: An integrated circuit servo system demodulator that incorporates a high speed gain stage with DC offset cancellation. The gain stage receives a differential voltage signal representing a servo burst and converts the differential voltage signal to a differential current signal by a transconductance amplifier. The differential current signal is full-wave current rectified and converted to a full-wave rectified voltage signal by a transimpedance amplifier. A DC offset cancellation circuit is coupled between the full-wave current rectifier and transimpedance amplifier and functions to mirror and subtract, from the rectified current signal directed to the transimpedance amplifier, any DC leakage current developed by the rectifier which would generate a DC offset voltage through the transimpedance amplifier.

Abstract: A head position signal demodulator that demodulates a position signal indicating the position of the magnetic head in the disk radius direction based on a servo pattern recorded on the magnetic disk includes a waveform shaping circuit which shapes an input signal obtained from the magnetic head according to the servo pattern and a phase comparison circuit which compares a phase of an output signal of the waveform shaping circuit and a phase of a reference signal and outputs a phase difference signal. The head position signal demodulator also includes a position signal generation circuit that generates a position signal of the magnetic head based on the phase difference signal, and a phase shifter which changes the phase of the reference signal during micro jogging, for an amount of the phase which has been set according to the amount of the micro jogging.

Abstract: A method of generating a position error estimate generates a phase field signal and a position error field signal. A set of operations is performed on the phase field signal and the same set of operations is performed on the position error field signal. The result obtained by performing the set of operations on the position error field signal is divided by the results obtained by performing the set of operations on the phase field signal. The result of the division is the position error estimate. In addition, a demodulation circuit is provided that utilizes field ratioing.

Abstract: A technique for reading data from a magnetic disk includes the steps of providing the magnetic disk including a cylinder having a plurality servo sectors, a plurality of data sectors, and a zone data table, the plurality of servo sectors including a first servo sector, a second servo sector, a third servo sector, a fourth servo sector, and a fifth servo sector, the zone data table including at least a nominal timing latency between the fourth servo sector and a data sector from the plurality of servo sectors, reading the first servo sector, the second servo sector, the third servo sector, and the fourth servo sector from the magnetic disk, determining a first timing deviation for the first servo sector between the first servo sector and the second servo sector, determining a second timing deviation for the second servo sector between the second servo sector and the third servo sector, predicting a predicted third timing deviation for the fourth servo sector between the fourth servo sector and the fifth servo

Abstract: A method of producing a position error signal includes storing a normal position error value generated from a normal servo field and a quadrature position error value generated from a quadrature servo field, where the normal servo field is ninety degrees out of phase from the quadrature servo field. A position error numerator is created by arithmetically combining the normal position error value and the quadrature position error value. A position error denominator is created based on the normal position error value and the quadrature position error value. The position error signal is produced by dividing the position error numerator by the position error denominator.

Abstract: Desired data recorded in a recording medium is read as a result of a head scanning a desired track, track tracking information for detecting the amount of displacement of said head with respect to the track and address information for identifying the recorded data are also recorded in said recording medium, and the track tracking information and the address information are used so that the head scans the desired track properly. The recording medium is used in which recording medium the track tracking information and the address information is disposed so that the head first scans the track tracking information and then scans the address information. Whether the track, which the head scans, is the desired track is determined from the address information. The amount of displacement of the head with respect to the track is detected from the track tracking information. The desired data is read from the desired track.

Abstract: A method of controlling a disk drive that reduces the space on the data storage surface of a storage disk otherwise effectively required to be taken up by embedded servo sectors. In disk drives employing wide-writer, narrow-reader, dual element heads, each servo burst field ends with a burst correction value (BCV) field. This BCV field enables the wide-writer head to be accurately positioned within track boundaries before writing begins to the data sector following a servo sector. The present invention takes advantage of the fact that burst correction values are only required by the head incident to data writing operations. Since a finite settle time is required to switch the read channel from servo mode to user data mode, and since the BCV field is not needed for reading operations, mode switching and channel settling can begin while the head is still passing over the BCV field.

Abstract: A hard disk drive (HDD) magnetically reading and writing digital data, and measuring the track pitch of a hard disk drive to detect more accurately the position error signal on each disk. The track pitches are calculated according to heads and zones, and compared with a reference track pitch as measured and averaged over all of the disks. The track pitches corresponding to the calculated track pitches are updated when detecting the calculated track pitches are the same for less than the reference track pitch. The track pitches corresponding to the calculated track pitches measured in accordance with head number and zone number are updated when detecting that the calculated track pitches are greater than the reference track pitch.

Abstract: A synchronous digital demodulator and method for demodulating a read signal including a user data waveform and a servo waveform which are generated by a read head as the read head passes over a user data area and a servo area, respectively, on a medium in a storage device. The user data waveform is converted to a series of digital user data values at a user data sample rate. The series of digital user data values are then applied to a user data detector circuit. The servo waveform is converted to a series of digital servo values at a servo sample rate, which is independent from the user data sample rate. The series of digital servo values are demodulated synchronously with the servo waveform to produce a position error value indicative of a position error of the read head relative to a location on the medium.