Abstract: A method and system determines the position of a transducer head based on permanent servo marks in which the width of the permanent servo marks is greater than the width of the data tracks they are used to identify. The method includes receiving readback signals in response to the permanent servo marks arranged as a number of null bursts and generating position error signals with respect to each null burst. Region based information is extracted based on the position error signals, and the region based information is used in conjunction with the position error signals to generate region-based displacement estimates with respect to each null burst. The region-based estimates are then combined to generate a final displacement estimate that describes the estimated distance between a transducer head and the centerline of a desired data track.

Abstract: Embodiments in accordance with the present invention ensure that the pitch of a servo write track is accurately controlled. According to one embodiment of the present invention, a Self Servo Write (SSW) uses different methods and sequences to identify read-write offsets (RWOs) and calculate target positions in inner and outer diameter sides of a magnetic disk. In the inner diameter-side area, the SSW controller uses the readout of a radial pattern written on a recording surface and a reference value to identify the RWO. The SSW controller uses the RWO value identified in the inner diameter-side area to anticipate an RWO value in the outer diameter-side area. In the outer diameter-side area, the SSW controller uses the anticipated RWO value to determine the target position of each servo write track.

Abstract: According to one embodiment, a hard disc apparatus comprises a disc, wherein areas between neighboring servo areas are allocated to data areas including data sectors, a head module, and a storage module configured to store head alignment data, wherein the head alignment data are defined for the data areas, and includes information indicating an interval from the servo area to a first data sector, information indicating a data area in one track, a first data sector which is a start sector of the track, and information indicating the presence/absence of a defective sector including a primary defect, and the start sector of a track including the defective sector is a data sector next to the defective sector.

Abstract: The information reproducing method manages an average magnetization state of each sector on a bit-patterned recording medium as sector management information and sets an information reproduction condition for the sector on the bit-patterned recording medium, based on the sector management information.

Abstract: Embodiments of the present invention provide accurate pitch control of a servo write track. A Self-Servo-Write (SSW) according to an embodiment of the present invention determines a reference APC by reading a mark formed on the recording surface corresponding to the propagation head prior to starting the product servo pattern writing. The accurate size of the mark in the radial direction is known previously. The reference APC is for determining the track pitch, and by using the mark with the determined size, the product servo patterns can be written with a desired and accurate track pitch.

Abstract: On a magnetic recording medium, M sets of burst patterns are formed along a direction of rotation of a substrate in each burst pattern region, where M is a natural number of two or higher. Each burst pattern is formed so as to include two types of burst signal units that are positioned at different distances from a center of data track patterns and have an equal length along a radial direction of the substrate. The length along the radial direction is (2·M/N) times the track pitch, where N is a natural number of two or higher.

Abstract: The present invention is directed to a method and apparatus for providing an absolute reference point on a disk surface of a disk drive. A write head associated with the disk surface is used to write spirals of servo information thereon, for example, under control of a servo track writer. The spirals of servo information include standard spirals and special spirals. In one embodiment, the special spirals are shorter than the standard spirals and the special spirals are rotationally non-symmetric. For example, an unequal number of standard spirals are interposed between one pair of adjacent special spirals relative to the number of standard spirals interposed between other pairs of adjacent special spirals. The special spirals may take a variety of other forms to distinguish themselves from standard spirals.

Abstract: A magnetic disk incorporated into a magnetic disk device is divided radially into a plurality of areas. An inner-circumference area has servo information written thereon at a low frequency. An outer-circumference area has servo information written thereon at a high frequency. The magnetic disk device creates concentric tracks on the magnetic disk with a magnetic disk rotation center as the center of the concentric tracks and selects a dividing track that acts as a demarcation for switching the area from which servo information will be read. The magnetic disk device then deletes all the servo information that is not going to be read in each of the areas divided by the dividing track.

Abstract: According to one embodiment, disclosed herein is a disk drive that has a disk of discrete-track media (DTM) type. The DTM disk has servo regions. Each servo region has dividing grooves and non-servo data parts. Each dividing grooves extends along the centerline of any projecting region having a width larger than a prescribed value. Each non-servo data part suppresses reproduction noise. The disk drive has a read/write channel that includes a reproduced-signal processing unit. This unit reproduces servo data from each servo region.

Abstract: Servo patterns and associated methods of fabricating servo patterns are described. For patterned storage media, data sectors and servo sectors may be patterned using self-assembly. In one embodiment, self-assembly is used to form a first array of islands and a second array of islands in servo sectors that are track-wise offset. A servo writing process is then performed to write a desired servo pattern in the arrays, such as for burst fields, synchronization fields, etc.

Abstract: A magnetic disk for a hard disk drive comprising a plurality of physical sector sizes is disclosed. The magnetic disk includes a first sector size area physically formatted according to a first physical sector size and a second sector size area physically formatted according to a second physical sector size different from the first sector size by a multiple of the first sector size wherein the second sector size can be presented externally as multiple sectors of said first sector size.

Abstract: On an information recording medium, a data track pattern and a servo pattern composed of a concave/convex pattern including a plurality of convex parts are formed on at least one surface of a substrate and respective concave parts in the concave/convex pattern are filled with non-magnetic material. In the concave/convex pattern that constructs the data track pattern, the respective convex parts are formed concentrically or in a spiral. In the concave/convex pattern that constructs the servo pattern, a unit convex part length along a direction of rotation of the substrate is set so that a value produced by dividing the unit convex part length by a distance from a center of the data track pattern decreases from an inner periphery to an outer periphery.

Abstract: A magnetic recording medium includes a servo area where servo data used for detecting a position of a magnetic head on a magnetic recording medium is recorded; and a writable data area, arranged side by side with the servo area in a track direction, on which user data is written by the magnetic head. The servo area includes a preamble area where a preamble recording pattern that represents data used for providing a clock synchronization of the servo data is formed by a plurality of magnetic sections; and a burst area where data used for detecting a relative position of the magnetic head with respect to a track center position of the servo data is recorded and on which a single burst recording pattern which is a layout pattern that tilts to the preamble recording pattern with a predetermined tilt angle is formed by a plurality of magnetic sections.

Abstract: A magnetic storage system includes a disk, a head, an actuator, and a servo controller. The servo controller monitors a value, such as a position error signal (PES) sample value, a predicted PES sample value, and the like, that is based on servo information provided by the head. The servo controller provides a signal to inhibit writing by the head based on a comparison of the monitored value with a threshold, such as a write fault window (WFW), a PES plus Velocity (PPV) threshold, and the like. The servo controller sets the threshold to a first value based on at least one of an on-track track misregistration (TMR) value and a seek settle TMR value. When the servo controller determines that the head is subject to a vibration condition, the servo controller sets the threshold to a second value that is different from the first value.

Abstract: A magnetic recording-reproducing apparatus for recording or reproducing information on or from a magnetic recording medium constituted of plural recording areas containing sectors joined together, comprises a memorizing unit for memorizing information on positional deviation of the sectors at the boundary between adjacent recording areas, and a controlling unit for controlling movement of a magnetic recording head in accordance with the information on positional deviation in the memorizing unit when the magnetic recording head moves between the sectors at the boundary between adjacent recording areas.

Abstract: A disk drive self-servo writes on a storage disk. Servo bursts are self-written along a track using a transducer, a position error signal (PES) indicating repeatable runout due (RRO) for the servo bursts is determined using a reference pattern, an embedded runout correction (ERC) value is calculated based on the PES and stored in a corresponding servo sector, and then the disk drive self-writes other servo bursts.

Abstract: According to one embodiment, in a disk drive having a disk medium on which servo data is recorded, servo-write management information is recorded on the disk medium, in the form of binary data based on the 0 or 180 degrees out of phase pattern composed of the servo burst signals included in the servo data and being out of phase. The disk drive includes a servo-data reproducing unit that reproduces the servo-data and the servo-write management information.

Abstract: A magnetic recording medium includes a servo area where servo data used for detecting a position of a magnetic head on a magnetic recording medium is recorded; and a writable data area, arranged side by side with the servo area in a track direction, on which user data is written by the magnetic head. The servo area includes a preamble area where a preamble recording pattern that represents data used for providing a clock synchronization of the servo data is formed by a plurality of magnetic sections; and a burst area where data used for detecting a relative position of the magnetic head with respect to a track center position of the servo data is recorded and on which a single burst recording pattern which is a layout pattern that tilts to the preamble recording pattern with a predetermined tilt angle is formed by a plurality of magnetic sections.

Abstract: In an implementation, a media drive comprises bit patterned magnetic media and one or more modules. The one or more modules are to cause data to be written on the bit patterned magnetic media in a data sector that includes a synchronization mark disposed between data blocks of the data sector.

Abstract: On a magnetic recording medium, M sets of burst patterns are formed along a direction of rotation of a substrate in each burst pattern region, where M is a natural number of two or higher. Each burst pattern is formed so as to include two types of burst signal units that are positioned at different distances from a center of data track patterns and have an equal length along a radial direction of the substrate. The length along the radial direction is (2·M/N) times the track pitch, where N is a natural number of two or higher.

Abstract: A magnetic recording medium includes a servo area where servo data used for detecting a position of a magnetic head on a magnetic recording medium is recorded; and a writable data area, arranged side by side with the servo area in a track direction, on which user data is written by the magnetic head. The servo area includes a preamble area where a preamble recording pattern that represents data used for providing a clock synchronization of the servo data is formed by a plurality of magnetic sections; and a burst area where data used for detecting a relative position of the magnetic head with respect to a track center position of the servo data is recorded and on which a single burst recording pattern which is a layout pattern that tilts to the preamble recording pattern with a predetermined tilt angle is formed by a plurality of magnetic sections.

Abstract: A method determines RW head radial position relative to tracks within a magnetic data disc. This involves sensing both a S-burst signal and a P-burst signal with the RW head. The S-burst signal and P-burst signal are associated with a two-burst servo pattern on the magnetic disc. The S-burst pattern has a phase that remains constant radially across tracks within the magnetic disc. The P-burst has a second phase that rotates radially across tracks within the magnetic disc. By determining a phase difference between a sensed S-burst signal and P-burst signal, it is possible to determine the RW head radial position relative to the tracks on the magnetic disc.

Abstract: A magnetic recording medium includes a servo area where servo data used for detecting a position of a magnetic head on a magnetic recording medium is recorded; and a writable data area, arranged side by side with the servo area in a track direction, on which user data is written by the magnetic head. The servo area includes a preamble area where a preamble recording pattern that represents data used for providing a clock synchronization of the servo data is formed by a plurality of magnetic sections; and a burst area where data used for detecting a relative position of the magnetic head with respect to a track center position of the servo data is recorded and on which a single burst recording pattern which is a layout pattern that tilts to the preamble recording pattern with a predetermined tilt angle is formed by a plurality of magnetic sections.

Abstract: A magnetic recording disk drive uses a disk having pre-patterned servo sectors extending generally radially across the data tracks. The servo sectors include at least two position error signal (PES) bursts or fields. The phases of the PES fields in the servo readback signal are demodulated to generate a PES to control the disk drive actuator for positioning the read/write heads. Each field contains generally radially directed magnetized stripes, with each stripe comprising a plurality of discrete radially-spaced generally parallelogram-shaped islands, each island having its length oriented at an acute angle relative to a track centerline. The stripes have alternating polarity of magnetizations in the along-the-track direction.

Abstract: A track follow controller includes a burst selector selecting at least one burst pair based on burst pair selection data. A linear position calculator calculates a primary head position and a secondary head position based on the at least one burst pair, and calculates a head linear position based on the primary head position and the secondary head position.

Abstract: A disk drive is disclosed comprising a disk having a plurality of tracks, wherein each track comprises a plurality of data sectors and a plurality of servo sectors. The disk drive further comprises a head actuated over the disk, the head comprising a read element radially offset from a write element by a reader/writer offset. In order to rewrite a marginal servo sector detected in a target track, control circuitry within the disk drive relocates user data recorded in a first data sector of a near adjacent track to a staging memory. Servo data is written over the first data sector, and the read element is used to read the servo data written over the first data sector to actuate the head to rewrite the marginal servo sector of the target track. The user data stored in the staging memory is then rewritten to the first data sector.

Abstract: The present invention provides a positioning control device and a disk device for shortening a calculation delay time. Upon detection of a position signal from a demodulation circuit, an MCU of the disk device calculates a position error, and following calculation of a control amount, executes determination and correction processing. A variable value prior to the start of calculation is stored in a save area of a memory (or a save memory) such that when the variable value is to be reset as a result of the determination and correction processing, the variable value is read from the save area, the reset variable value is stored in an overwrite area of the memory (or an overwrite memory), and calculation of the control amount is re-executed.

Abstract: A mark information is recorded in an area which is on a circumference of a magnetic disk corresponding to a last track in which a servo information write is ended or a track, which is one or two in front of the last track in which servo information is not written and the mark information is detected by returning a magnetic head in a radial direction of the magnetic disk by a fine movement stage after the magnetic head is moved to a next aimed track by a coarse movement stage. The servo information write position is detected by the magnetic head and the servo information is written in a servo information write position of a next track by positioning the magnetic head therein by using the fine movement stage.

Abstract: In a positioning control device based on control of an observer having a disturbance suppression function, a disturbance suppression function according to a head position is added without impairing the control characteristics of the observer. The position control device has an observer having a disturbance suppression function comprising a model of an actuator and a model of disturbance, and a table for storing an estimated gain of the observer according to a position of the head. And an estimated gain is acquired from the table according to the position of the head, and an estimated gain of the observer is changed so as to change the disturbance suppression frequency characteristic. The disturbance suppression characteristic can be optimized according to the position of the head in the radius direction or between disks, and vibration of the head can be prevented even if recording density is increased.

Abstract: On a magnetic recording medium, a servo pattern is formed in a servo pattern region on at least one surface of a substrate by a concave/convex pattern including a convex part, at least protruding end part of which is formed of magnetic material, and a concave part. The servo pattern region includes an address pattern region and a burst pattern region, wherein the convex part is formed in the servo pattern region so that a larger of an inscribed circle with a largest diameter out of inscribed circles on an open surface of the concave part formed in the address pattern region and an inscribed circle with a largest diameter out of inscribed circles on an open surface of the concave part formed in the burst pattern region is an inscribed circle with a largest diameter out of inscribed circles on an open surface of the concave part formed in the servo pattern region.

Abstract: A disk drive is disclosed including a disk having a first and second set of time-based servo patterns. The first set of time-based servo patterns comprises a first cyclical pattern that repeats radially over the disk, and the second set of time-based servo patterns comprises a second cyclical pattern that repeats radially over the disk, wherein each cyclical pattern comprises a plurality of timing marks. One of the first cyclical patterns overlaps at least part of a first servo track, and one of the second cyclical patterns overlaps at least part of the first servo track. At least one of the first and second set of time-based servo patterns are demodulated by detecting first and second time intervals relative to the timing marks, and a control signal for actuating the head is generated in response to the first and second time intervals.

Abstract: Various systems and methods for providing head location feedback are disclosed herein. For example, one system includes an interface circuit that is operable to receive an information stream retrieved from a magnetic storage medium. The magnetic storage medium includes one or more tracks that each include a plurality of sectors. The sectors include burst information that can be utilized to aid in positioning a read/write head assembly over a magnetic storage medium. The systems further include a multiple sector error detection circuit. The multiple sector error correction circuit is operable to phase align samples of a burst obtained from one sector with samples of a burst obtained from another sector. An amplitude of each of the bursts is determined, and the determined amplitudes are combined. The combined amplitudes correspond to a position error of the read/write head assembly relative to the magnetic storage medium.

Abstract: A track map of a disk drive is generated to compensate for various conditions. A track map is a stored measurement of every “half” servo track width on a disk. Every servo half track width is measured in the factory on a disk and then the data is stored on the disk for use during drive operations. When an individual track is accessed, the appropriate servo half track width data is pulled from memory and is used to adjust a scale factor for that local half track width. The track map may be used to compensate for various conditions including varying servo track width, microjog distance, and data track spacing.

Abstract: A system and method for a servo controller (SC) used in an embedded disk controller for adjusting stored servo skew values based on measured skew values is provided. The system includes, a servo timing controller, wherein the servo timing controller includes a first register that stores measured servo skew values at a given time; a first set of registers that receive stored skew values and the measured skew values; and firmware that adjusts the skew values based on the measured skew values measured by a reference timer. The process includes, measuring actual skew values during a head change in a read operation; comparing the measured skew values with the stored skew values; adjusting the skew value based on the comparison; and adjusting a servo field timer based on the adjusted skew value.

Abstract: A magnetic recording disk drive uses a disk having pre-patterned servo sectors extending generally radially across the data tracks. The servo sectors include at least two position error signal (PES) bursts or fields. The phases of the PES fields in the servo readback signal are demodulated to generate a PES to control the disk drive actuator for positioning the read/write heads. Each field contains generally radially directed magnetized stripes, with each stripe comprising a plurality of islands forming a zigzag pattern. The stripes have alternating polarity of magnetizations in the along-the-track direction.

Abstract: In a method of measuring track widths in a hard disk drive a plurality of estimation values are calculated based on differences in intensity between a plurality first measurement signals produced in relation to a head of the hard disk drive based on a plurality of burst signals stored in servo sectors of a track when the head moves along the track on a first side of a center of the track, and a plurality of second measurement signals produced in relation to the head of the hard disk drive based on the plurality of burst signals when the head moves along the track on a second side of the center of the track opposite the first side. The estimation values are then normalized, and excessive variation in the track widths is detected based on the normalized estimation values.

Abstract: A servo pattern is formed in a servo pattern region on at least one surface of a substrate of a magnetic recording medium by a concave/convex pattern including a plurality of convex parts, at least protruding end parts of which are formed of magnetic material, and at least one concave part. The servo pattern region includes an address pattern region and a burst pattern region. The at least one concave part is formed in the servo pattern region so that a larger of an inscribed circle with a largest diameter out of inscribed circles on protruding end surfaces of the convex parts formed in the address pattern region and an inscribed circle with a largest diameter out of inscribed circles on protruding end surfaces of the convex parts formed in the burst pattern region is an inscribed circle with a largest diameter out of inscribed circles on protruding end surfaces of the convex parts formed in the servo pattern region.

Abstract: Provided is a magnetic recording apparatus including a magnetic recording medium having a magnetic recording position patterned of a magnetic substance and a read head reading information from the magnetic recording medium, wherein the magnetic recording medium includes: a data area having the magnetic recording position patterned including a plurality of data tracks; and a servo area including a servo burst for tracking the data tracks, wherein the servo burst includes a plurality of bursts deviating from one another in a downtrack direction, and a width of each of the bursts is equal to or greater than a width of the read head and narrower than twice the width of the read head. According to this structure, although data is reproduced using a read head having a greater width than a width of each of data tracks, a linear section in which an output voltage is reduced depending on a size of an off-track is formed. As a result, a dead zone can be removed.

Abstract: The delay time from the rotation start of a magnetic disk medium (M) to a servo pattern being read is obtained with respect to a radial position from the phase delay that the trajectory of a magnetic head (H) by a rotary actuator causes with respect to the radial direction axis of the medium (M), and is reflected to the generation delay time of a servo gate signal used at servo reading.

Abstract: On an information recording medium, a data track pattern and a servo pattern composed of a concave/convex pattern including a plurality of convex parts are formed on at least one surface side of a substrate and respective concave parts in the concave/convex pattern are filled with non-magnetic material. The concave/convex pattern that constructs the servo pattern is divided into a plurality of ring-shaped regions that are concentric with the data track pattern and has a unit convex part length along a direction of rotation of the substrate set in each ring-shaped region so that a value produced by dividing an average length of the unit convex part length in each ring-shaped region by a distance from a center of the data track pattern to the ring-shaped region decreases from ring-shaped regions in an inner periphery to ring-shaped regions in an outer periphery.

Abstract: The invention provides a servo pattern that is stable for long time, easily writable, and excellent in S/N. DC-signal area included in a burst area of a servo pattern comprises combination of positive and negative DC-signals, low-density dummy bit, or pattern having phases that are deviated each other so that the sum of magnetization of the burst area of the servo pattern is equalized to 0.

Abstract: In a magnetic recording medium including a servo pattern region having a servo pattern formed of a concave/convex pattern having convex portions and concave portions and a data recording region, the region having a data track pattern, the concave portions are formed in an address pattern region of the servo pattern region such that the maximum lengths, which are located in the respective same radius regions of the respective lengths along the rotating direction of a substrate of the projecting end surfaces of the convex portions constituting the concave/convex pattern are set to first lengths that are double the minimum lengths along the rotating direction of the projecting end surfaces of the convex portions in the respective same radius regions. With this arrangement, the magnetic recording medium can securely read a magnetic signal and has a servo pattern having excellent surface smoothness.

Abstract: In a magnetic disk device, oscillation occurring at a frequency higher than Nyquist frequency is suppressed. In one embodiment, a multi-late filter having a resonance point at a frequency higher than the intended Nyquist frequency is introduced in a previous stage of a controlled object. At that time, since a resonance characteristic of the multi-rate filter is aliased by a sampler, the multi-rate filter is designed such that the resonance point after the aliasing is stabilized in phase by a following compensator.

Abstract: A magnetic recording medium and a method of fabricating the same are provided. The magnetic recording medium in which a position for magnetic recording is patterned with a magnetic material, includes a magnetic recording layer which includes a data area having a plurality of data tracks, and a servo area having a servo burst for following the data tracks, wherein the servo burst includes a plurality of bursts disposed in a zigzag structure along a downtrack direction, and each of the bursts includes a plurality of burst pieces having different coercivities from each other. The magnetic recording medium is subjected to two servo-recording processes, so that a signal similar to an alternative signal written in a burst having a burst pattern used in a related art continuous medium can be obtained.

Abstract: According to one embodiment, a servo-writing method for use in a disk drive, in which a CPU causes a head to record final patterns in a disk, by using the multi spiral servo pattern recorded in the disk. The CPU uses a designated spiral servo pattern, positioning the head at a target position, so that the head may write the final patterns at the target position and may read sector-address data contained in the final patterns.

Abstract: A position error calculator for an embedded disk controller including a burst selector that selects a burst pair based on a burst pair format. The burst pair format includes at least a first burst pair format that includes x bursts and a second burst pair format that includes y bursts and x is not equal to y. A linear position calculator calculates head linear position based on the burst pair format.

Abstract: Provided is a self servo writing method of writing a final servo signal based on a reference servo signal in a hard disk drive, and more particularly, a method of writing a uniform final self servo signal by compensating for a non-uniform width of tracks where a reference servo signal is written, a hard disk drive using the method, and recording medium storing the method. The self servo writing method includes measuring the width of a target track based on the reference servo information, calculating the deviation between the measured width and a target width, and writing the final servo information while following the target track based on the center position of the target track calculated using the reference servo information and the calculated deviation of track width. According to the self servo writing method, the final servo information is written on tracks having a uniform width, even if the reference servo information is written on tracks having a non-uniform width.

Abstract: A magnetic recording disk drive has disks with identical pre-patterned servo patterns on their front and back surfaces and a servo control system for positioning the read/write heads using the servo signals from the identical servo patterns. The servo sectors on the two disk surfaces form identical patterns of angularly spaced arcuate-shaped lines that extend generally radially across the data tracks. The arcuate-shaped lines on one surface, the front surface, generally replicate the path of the recording head as it is moved across the data tracks by a rotary actuator, so that there is a constant sampling rate of the servo sectors on the front surface regardless of radial position of the head. However, the arcuate-shaped lines on the other surface, the back surface, do not replicate the path of the recording head so the servo sampling rate is not constant but varies with radial position of the head.

Abstract: A hard disk drive with a disk that includes a first group of tracks and a second group of tracks. The second group of tracks are used to write large blocks of data. For example, data in the second group may be video or audio. The second group of tracks has a higher track density than the first group of tracks. The large data block is written sequentially in the second group of tracks so that there is only one adjacent track write within the group. Using only one adjacent track write allows the tracks within the second group to be overlapped to increase track density.

Abstract: A track map of a disk drive is generated to compensate for various conditions. A track map is a stored measurement of every “half” servo track width on a disk. Every servo half track width is measured in the factory on a disk and then the data is stored on the disk for use during drive operations. When an individual track is accessed, the appropriate servo half track width data is pulled from memory and is used to adjust a scale factor for that local half track width. The track map may be used to compensate for various conditions including varying servo track width, microjog distance, and data track spacing.