Abstract: Patterned-media magnetic recording disks are made from a master template that has nondata regions that contain a pattern of one or more discrete nondata islands and discrete gaps, with the pattern representing a scrambled number. All disks made from the master template, or from replica molds made from the master, will have the same patterns. When the disks are DC-magnetized so that all the nondata islands are magnetized in the same direction, these patterns will include one or more of discrete magnetized nondata islands and discrete nonmagnetic gaps that are scrambled in a pseudo-random manner. During operation of the disk drive the patterns are detected by the read head and interpreted within the disk drive using knowledge of the pseudo-random scrambling function, so that reading and writing of data can occur in the conventional manner. If the disks are copied in an attempt to replicate the master template, the resulting disks will be inoperable in a disk drive because of the scrambling.

Abstract: In a servo control loop, phase detection between a clock signal and servo burst fields on a movable storage media is carried out with compensation for the effects of frequency variation in the timing of servo burst fields.

Abstract: A method and apparatus for measuring latency in a communication path is provided. The technique includes driving a signal such as a square wave on the communication path, such as a write path such that it travels around the write-read path, and sensing a returned signal at one end of the write-read path. A square wave signal corresponding to the square wave driven on the write path is delayed by a predetermined phase thus generating a delayed signal. The returned signal and the delayed signal are mixed, producing a mixed signal. The mixed signal is integrated to obtain an integrated output. The phase by which the delayed signal is shifted is successively adjusted. Returned signals are mixed with such delayed signals until the integrated output is equal to zero. The phase shift amount that results in a nulled integrated output, less a quarter cycle of the square wave, is equal to the round trip latency of the write-read path.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted by a sync mark at a sync mark interval. The head is positioned over the disk and used to read the spiral tracks to detect a plurality of spiral-to-spiral times each representing a time between consecutive spiral crossings. A velocity of the head is estimated in response to the spiral-to-spiral times, and velocity feedforward compensation values are generated from the estimated head velocity. A control signal is generated to position the head over the disk in response to the velocity feedforward compensation values. When the detected spiral-to-spiral times are substantially constant, position feedforward compensation values are initialized in response to the velocity feedforward compensation values.

Abstract: A data storage drive comprises a storage disk, a read/write head, and signal processing circuitry in signal communication with the read/write head. The read/write head is operative to read data from and write data to the storage disk at a plurality of data transfer rates. Moreover, the signal processing circuitry is powered by a variable power source. The variable power source varies supply voltage to the signal processing circuitry as a function of a current one of the data transfer rates of the read/write head. Power consumption is reduced in this manner.

Abstract: A recording medium can include multiple helicoid patterns arranged in multiple helicoid groups, e.g., first and second helicoid groups. Operating a disk drive can include switching between helicoid groups to maintain the alignment of the head with respect to a target track of the rotating recording medium. Enabling a switch can include receiving a waveform produced by a head operated with respect to a rotating recording medium, generating first information from one or more portions of the waveform corresponding to the helicoid patterns of the first helicoid group; generating second information from one or more portions of the waveform corresponding to the helicoid patterns of the second helicoid group; and analyzing the second information with respect to the first information to generate calibration information. The calibration information can compensate for operational differences between using the helicoid patterns of the first helicoid group and the helicoid patterns of the second helicoid group.

Abstract: Recording media comprises multiple first and second patterned media islands sequentially placed at different first and second radii along a length of a recording track. A recording head sequentially accesses the first and second islands as the head moves along a length of the recording track. Circumferential spacings between sequential first and second islands along the length of the track vary as a skew function of a track radius.

Abstract: A method includes: writing data to a bit-patterned media at times determined by a clock having a period that is offset from a bit island period by a fixed offset to create one insertion or one deletion approximately within a predetermined number of bit islands, reading the data, and correcting the read data using error correction. An apparatus that implements the method is also provided.

Abstract: According to one embodiment, a magnetic disk storage device includes a magnetic disk, a head, a clock generator, an estimating module, and a controller. The magnetic disk includes a servo area and a corresponding data area, and has a surface divided into zones in the radial direction. The basic frequency varies in the servo area depending on the zones. The head is driven to read a signal from the magnetic disk. The clock generator generates a clock signal for decoding a signal read from the data area corresponding to the servo area based on a signal read from the servo area. The estimating module estimates the position of the servo area in the radial direction, from which the head reads a signal next. The controller controls the clock generator to generate a clock signal of the basic frequency before the head reaches the servo area based on the estimated position.

Abstract: A method is disclosed for demodulating a spiral servo track recorded on a disk of a disk drive. The spiral servo track comprises a high frequency signal interrupted by a sync mark at a sync mark interval. A demodulation window is enabled relative to a spiral servo track crossing, and a plurality of sync marks are detected in a sync mark window of the demodulation window. A reliability metric is generated for each of the detected sync marks, wherein the reliability metrics are evaluated to select one of the detected sync marks. A clock is synchronized in response to the selected sync mark.

Abstract: A hard disk drive with a disk that has a plurality of data fields. Each data field includes a sync field and a plurality of sync marks. Data is written onto the disk in accordance with a write clock. The write clock is generated and synchronized by the sync field and the sync marks. The sync marks are dispersed throughout the data field so that the write clock is resynchronized as data is written onto the field.

Abstract: A disk drive is disclosed comprising a disk and a head actuated over the disk. The disk comprises a plurality of tracks, wherein each track comprises a plurality of data sectors. A read command is received from a host to read data from a target data sector. When it is determined that the target data sector has not been written by the host, dummy data is returned to the host.

Abstract: A patterned-media magnetic recording disk drive uses an optical system for accurately clocking the write data. The disk has concentric data tracks patterned into discrete magnetizable data islands with nonmagnetic spaces between the islands. As the disk rotates, a radiation source directs near-field radiation to the islands and spaces, and a radiation detector receives reflected radiation. The radiation is directed from the source through an optical channel or waveguide on the air-bearing slider that supports the read and write heads. The optical channel or waveguide has a near-field transducer at the disk-facing surface of the slider where the near-field radiation exits and reflected radiation returns. The reflected optical power varies depending on whether the near-field transducer couples to an island or a space, so the radiation detector output signal represents the frequency and phase of the islands as the disk rotates.

Abstract: A disk drive that approximates spiral slope in spiral patterns is disclosed. The disk drive includes a disk having at least one spiral pattern that extends radially across the disk, a head to read a portion of the at least one spiral pattern, and a processor to approximate a spiral slope of the portion of the at least one spiral pattern. The processor approximates the spiral slope of the portion of the at least one spiral pattern by implementing operations including: reading amplitude values for the portion of the at least one spiral pattern; determining an amplitude value distribution based on the amplitude values; determining a curve-fitted function for the amplitude value distribution; and determining an approximate spiral slope based on the curve-fitted function.

Abstract: According to one embodiment, a disk drive that includes a disk and a disk controller is provided which effectively correct data errors that are generated at the time of reproducing data. The disk has a data-recording area constituted by a set of magnetic dots that are physically separated from one another. The disk controller uses error-correcting codes to determine an error that shows a change in the total number of bits in a data-bit string of the data set reproduced.

Abstract: A magnetic device includes a read sensor, a writer and a synchronization sensor. The magnetic device is configured for writing information to and reading information from a magnetic medium that includes a plurality of discrete magnetic bits. The writer includes a write element, a first return element magnetically coupled to the write element, and a second return element magnetically coupled to the write element. The write element is positioned in between the first and second return elements. The synchronization sensor is located adjacent to the write element of the writer in a closely spaced arrangement, and is configured to generate a signal as a function of a sensed magnetic bit. The signal is used to position the writer element relative to the sensed magnetic bit.

Abstract: A disk drive is disclosed comprising a disk and a head actuated over the disk. The disk comprises a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted by a sync mark at a sync mark interval. A first spiral track comprises a first sync mark from an outer diameter of the disk to a reference radial location and a second sync mark from the reference radial location toward an inner diameter of the disk. A second spiral track comprises the second sync mark from the outer diameter of the disk to the reference radial location and the first sync mark from the reference radial location toward the inner diameter of the disk. The first sync mark is different than the second sync mark.

Abstract: A data-storage disk includes a disk sector for storing data and a servo wedge located at the beginning of the sector. The servo wedge indentifies the sector in conjunction with both an initial positioning of a read-write head and a data read or write operation. By using a servo wedge to provide both an initial head position on disk spin up and a head position during a read or write operation, one can increase a disk's data-storage capacity by reducing the number of, or altogether eliminating, spin-up wedges.

Abstract: A disc drive system provides increased reliability by detecting and correcting errors associated with bit-patterned media. Write synchronization errors associated with bit-patterned media are addressed by including data storage for temporarily storing data that is being written to the disc drive. The data is read from both the disc drive and the storage medium and compared to detect write synchronization errors. A disc drive system for correcting write synchronization errors includes an encoder, non-volatile storage, and decoder device for implementing a parity-based scheme for increased reliability. Data strings being written to the disc drive are combined in an encoder to generate a parity string. The address of the data being written to the disc drive, along with the updated parity string is stored to the non-volatile storage. The data strings are read from the disc drive by the decoder.

Abstract: A controller for a self-servo writer includes a wedge writer that writes a first set of wedges of servo data and a second set of wedges of servo data between wedges of the first set. A wedge entender writes first extensions to the first set of wedges using at least one of a position reference and a timing reference from a corresponding wedge of the second set.

Abstract: A detector recovers servo data from a servo signal generated by a read-write head, and determines the head-connection polarity from the recovered servo data. Such a detector allows a servo circuit to compensate for a reversed-connected read-write head, and thus allows a manufacturer to forego time-consuming and costly testing to determine whether the head is correctly connected to the servo circuit.

Abstract: Magnetic reference patterns may be generated on a disk or other magnetic media without the need for seed wedges. This involves writing a first magnetic reference pattern to the disk with a servo writer. The disk may then be transferred to a hard disk drive. Control circuitry within the hard disk drive may recognize the first magnetic reference pattern and then position a RW head within the hard disk drive based on the first magnetic reference pattern. As the RW drive is accurately positioned based on the first magnetic reference pattern a second magnetic reference pattern may be written to the disk using the RW head. The RW head location is determined based on the velocity and phase between the read-write head and spiral sync marks contained within the first magnetic reference pattern.

Abstract: A storage channel, e.g., for a disk drive system, may asynchronously sample and buffer an entire sector, and then process the buffered sector to recover timing information. The storage channel may operate in an open-loop and utilize an exhaustive search to determine timing parameters. Alternatively, the storage channel may operative in a closed-loop, processing the sector once, and feeding back information obtained during decoding to the timing loop.

Abstract: An apparatus includes an address mark detector having an address mark output. The address mark output is indicated as erroneous if errors in a detected address mark exceed an error threshold function. The error function has a variation as a function of a difference between a detected address mark time and a reference address mark time.

Abstract: A head capable of favorite thermally-assisted magnetic recording without depending on the use of a near-field light generator is provided. The head comprises a write head element formed on the trailing side from a waveguide and comprising a first main pole. The first main pole and the waveguide are opposed to each other through a first clad layer, and a second clad layer is provided on a rear side from the first main pole. This gives that the end surface of the waveguide can be placed much close to the end surface of the first main pole apart by only a thickness of the first clad layer. As a result, the end surface of the first main pole can apply a sufficient intensity of write field to the intensity center and its vicinity of the light spot formed on the magnetic recording layer.

Abstract: Embodiments of the present invention provide a magnetic disk drive capable of controlling write/read positions by a method that takes the disturbance in the circumferential direction of a magnetic disk into consideration, thereby making it possible to improve the positioning accuracy. A magnetic disk drive in accordance with an embodiment of the present invention comprises: a magnetic recording medium on which information is written to each track thereof, the recording medium having a servo signal formed in the each track at specified intervals; a magnetic head including a read head for reading a signal from the magnetic recording medium, and a write head for writing information to the magnetic recording medium. At the time of writing/reading information by the magnetic head, a servo signal is detected from among signals read out by the read head.

Abstract: According to one embodiment, a write clock generator writes data to bits in a magnetic recording medium based on a write clock signal with a phase obtained by delaying the phase of a reference write clock signal. The write clock generator detects the amplitude of a read signal for the written data. The write clock generator repeats these operations with a phase delay varied. The write clock generator decides an optimum phase delay based on the amplitude detected for each phase delay.

Abstract: According to one embodiment, a disk drive comprising a magnetic disk of bit-patterned type is provided. The disk drive has a reproduction module, a measurement module, and a recording module. The reproduction module outputs a reproduced signal corresponding to the phase-shift measuring bits provided on the magnetic disk. The measurement module determines that the phase shift corresponding to the phase-shift measuring bits is the phase shift of a write clock signal if the reproduced signal is determined to be indefinite on the basis of the quantization value of the reproduced signal. The recording module records data corresponding to the data recording bits, by using the write clock signal adjusted by the phase shift.

Abstract: In a method of authorizing a supply for use with a printing system, a supply is provided having a memory containing a first and second codes and supply-specific data, which uniquely identifies the supply. The first code, the second code and the supply-specific data are retrieved from the memory of the supply. The first and second codes are translated using the supply-specific data. The translated first code is compared to a third code and the translated second code is compared to a fourth code. Use of the supply with the printing system is authorized when the translated first code corresponds to the third code and the translated second code corresponds to the fourth code. Use of the supply with the printing system is prevented when either the translated first code does not correspond to the third code, or the translated second code does not correspond to the fourth code.

Abstract: A control system includes a write head and a control module configured to signal the write head to write a servo test track on a rotating medium at a position relative to a reference servo track on the rotating medium. The servo test track is written on the rotating medium subsequent to an interrupt event. The reference servo track having been written to the rotating medium prior to the interrupt event, detects the position of the servo test track relative to the reference servo track and signals the write head to write a new servo track on the rotating medium based on the detected position of the servo test track relative to the reference servo track.

Abstract: A method and system for fabricating a magnetic recording device are described. The method and system include providing a mask layer on the magnetic recording device and imprinting a pattern in the mask layer to form a mask. The method and system also include transferring the pattern from the mask to the magnetic recording device. In another aspect, the method and system include providing a malleable mask layer on the magnetic recording device. In this aspect, the method and system also include depressing an imprint mask into the mask layer and curing the mask layer while the imprint mask is depressed into the mask layer to provide a mask having a pattern. The pattern may correspond to a read sensor and/or a perpendicular magnetic recording pole. The method and system also include transferring the pattern from the mask to the magnetic recording device.

Abstract: An LDPC encoder (304) includes a timing adjustment circuit (326) for performing timing adjustment on main data and outputting to a writing circuit (334), a parity generation circuit (328) for performing LDPC encoding on input signal series, generating the parity data, and outputting to the writing circuit (334), and the writing circuit (334) for sequentially receiving the main data and the parity data, and outputting to the storage apparatus via a write pre-compensation unit (305), a driver (306), and the like.

Abstract: Phase-error combination for a multi-channel data detection system with a phase locked loop for each channel, comprises receiving phase error information with respect to each channel; combination logic configured to combine the received phase error information and generate a combined phase error; and a phase-error output configured to apply the combined phase error to at least one channel phase locked loop. Additionally, error signal combination comprises receiving error information of a signal relevant to a phase locked loop with respect to each channel; combination logic configured to combine the received error signal information and generate a combined error signal, weighting the received error signal information from each channel, for example with reliability information. An error compensation output is configured to apply the combined, weighted error signal to at least one channel phase locked loop.

Abstract: A method of writing a servo pattern to a disk, wherein a servo pattern is generated in a processor. The generated servo pattern is then written to a disk. The servo pattern for a servo sector is preferably generated in a single routine.

Abstract: A technique is described for write synchronization phase calibration for storage media (e.g., bit patterned media). In one embodiment, a calibration write clock signal may be generated at a frequency offset from a nominal dot frequency of a bit patterned storage media. A periodic signal that was written to the media synchronous to the calibration write clock signal may then be read and mixed with a reference periodic signal at the nominal dot frequency to obtain a difference signal. This difference signal may be demodulated to determine a phase correction for write synchronization to the media.

Abstract: A hard disk control system comprises a phase adjust module, an offset adjust module, and a read/write timing module. The phase adjust module generates a phase adjust signal based on a phase difference between a first repeatable run out (RRO) field and a servo wedge field. The offset adjust module outputs a position calibration pattern to a storage medium based on the phase adjust signal; receives at least a portion of the position calibration pattern from the storage medium; and determines an offset based on a comparison between the output position calibration pattern and the received portion of the position calibration pattern. The read/write timing module determines a position to write a second RRO field on the storage medium based on the offset.

Abstract: A phase-acquisition (PA) loop for a read channel comprises an accumulator, a comparator, and a filter. The accumulator holds an acquired phase-correction value corresponding to a difference between a phase of a sample clock and a phase of data carried by a read signal, and provides the acquired phase-correction value to a circuit that modifies the read signal to compensate for the phase difference. The comparator receives a reference phase-correction value that also corresponds to the difference between the phases of the sample clock and the data, and generates an error signal that is related to a difference between the reference and acquired phase-correction values. And the filter causes the acquired phase-correction value to have a predetermined relationship to the reference phase-correction value.

Abstract: Frequency error combination for a multi-channel data detection system with a phase locked loop for each channel, comprises receiving frequency error information with respect to each channel; combination logic configured to combine the received frequency error information and generate a combined phase error, weighting the received frequency error information from each channel; and a frequency error output configured to apply the combined frequency error to at least one channel phase locked loop.

Abstract: A storage channel, e.g., for a disk drive system, may asynchronously sample and buffer an entire sector, and then process the buffered sector to recover timing information. The storage channel may operate in an open-loop and utilize an exhaustive search to determine timing parameters. Alternatively, the storage channel may operative in a closed-loop, processing the sector once, and feeding back information obtained during decoding to the timing loop.

Abstract: Phase-error combination methods for a multi-channel data detection system with a phase locked loop for each channel, comprises receiving phase error information with respect to each channel; combining the received phase error information and generating a combined phase error; and applying the combined phase error to at least one channel phase locked loop. Error signal combination comprises receiving error information of a signal relevant to a phase locked loop with respect to each channel; combining the received error signal information and generating a combined error signal, weighting the received error signal information from each channel, for example with reliability information. The combined, weighted error signal is applied to at least one channel phase locked loop.

Abstract: Methods, systems, and apparatus, including computer program products, are described for calibrating servos, and in some implementations for calibrating spiral servos for use in self-servo-write processes. In one aspect, a method is provided that includes determining a measured slope of a spiral, and calibrating radial spacing between servo tracks using the measured slope and a target slope.

Abstract: A disk drive that includes a head and a disk. The disk drive also includes a circuit that can detect head/disk contact from a jitter determined from a read signal provided by the head. The jitter may correspond to the time interval between two detected sync marks. Alternatively, the jitter may correspond to a change in frequency of a read clock generated from the read signal. These approaches allow for detection of head movement in a down track direction. Down track is a direction that is essentially parallel with the longitudinal axis of the head.

Abstract: In a method for causing data to be written to a non-volatile medium, an indication of a size of a sector or a sector fragment may be transmitted to a channel device, and an indication of a size of a codeword to be written in the sector may be transmitted to the channel device. Data to be iteratively encoded and written in the sector as the codeword may be transmitted to the channel device. A write gate signal corresponding to the sector or the sector fragment may be transmitted to the channel device to indicate to the channel device when to write to the sector or the sector fragment.

Abstract: The transfer of data from a host computer to a recordable disk in a disk drive operating on the host computer is managed. A buffer for temporarily storing data to be transferred between the host computer and the recordable disk is maintained, wherein the buffer comprises a plurality of host segments and a plurality of disk segments, and wherein each of the host segments and disk segments have a sector count value associated therewith. In a case where the transfer of data corresponds to a host segment, the host segment is selected from the plurality of host segments in the buffer. In a case where the transfer of data corresponds to a disk segment, the disk segment is selected from the plurality of disk segments in the buffer. In a case where a host segment is selected, the sector count value of the selected host segment is adjusted. In a case where a disk segment is selected, the sector count value of the selected disk segment is adjusted.

Abstract: A method leverages knowledge of the actual or ideal bit sequence to improve the performance of any sequence detector. This improved performance results by constraining the sequence detector when the sequence detector has knowledge of known patterns within the sample sequence. Embodiments may control or limit the effects of ISI on a readback signal in order to allow higher storage within physical media such as that of a HDD. This method involves reading an analog waveform from the physical media. The phase of this analog waveform is determined and it is sampled at regular intervals using a timing recovery scheme. This sample sequence is equalized (filtered) and sent to a sequence detector which will compare the received sequence to all possible transmitted sequences, generating a path through a trellis that represents the estimated sequence. That trellis path may pass through known states at certain times. This knowledge makes it possible to remove some of the paths under consideration.

Abstract: Various embodiments of the present invention provide systems and methods for performing data equalization. For example, various embodiments of the present invention provide data equalization circuits that include an equalization circuit and a transition adjustment circuit. The equalization circuit receives a series of at least two original data bits and replaces at least one of the two original data bits with an equalization pattern including two or more equalization bits. The original data bits correspond to an original data clock, and the two or more equalization bits correspond to an equalization data clock. The transition adjustment circuit is operable to modify an occurrence of a transition from one logic state to another logic state within the equalization pattern on a sub-equalization data clock basis.

Abstract: A method for synchronizing writing to a bit patterned media includes: reading bits from skipped blocks on the bit patterned media, using timing of bits read from the skipped blocks to update a write clock, and writing request data to physical blocks on the bit patterned media, interleaved with the skipped blocks. An apparatus that operates in accordance with the method is also provided.

Abstract: Various systems and methods for peak signal detection. As one example, a method for peak signal detection that includes receiving a signal is disclosed. The received signal includes a signal region where the signal is increasing in amplitude, another signal region where the signal is decreasing in amplitude, and a transitional signal region coupling the first two signal regions. In some cases, the transitional region is of zero duration and the signal transitions directly from the increasing region to the decreasing region. The method further include calculating a distance between the signal region of increasing amplitude and the signal region of decreasing amplitude, and determining a peak of the received signal that is one half the distance from the signal region of increasing amplitude.

Abstract: Methods, systems, and apparatus, including computer program products, are described for calibrating control loops, specifically phase-locked loops. In one aspect, an apparatus is provided that includes an oscillator model that generates a predicted phase based on an input, a first averaging submodule that generates an average predicted phase over a predetermined number of samples, and a first summing submodule that receives a first corrected phase error and generates a predicted repetitive phase disturbance using the first corrected phase error, the predicted phase, and the average predicted phase.

Abstract: An apparatus and associated method are described for use in a disk drive including a disk that that is supported for controlled rotation and for cooperating with a transducer arrangement for accessing the disk in performing a data operation. The disk includes an arrangement of servo track wedge segments for storing servo data such that a set of servo data is periodically available as the disk is rotated in relation to the transducer arrangement and the servo track wedges are separated by an arrangement of user data wedge segments for use in storing user data. Generally, a controller IC and a channel IC are provided. The servo data is transferred from the channel IC to the controller IC using one data protocol and user data is bidirectionally transferred between the channel IC and the controller IC using a different data protocol.