Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors, and a head actuated radially over the disk, wherein the head comprises a read element separated from a write element by a reader/writer gap. The head is positioned over a first servo track, and a clock is synchronized to servo data in first and second servo sectors of the first servo track. A first phase-offset of the clock is measured for the first servo sector, and a second phase-offset of the clock is measured for the second servo sector, wherein the first and second phase-offset correspond to an end of the reader/writer gap at the first servo track. The first and second phase-offset are averaged to generate an average phase-offset for the first servo track.

Abstract: A HDD including write components configured to operate within an operating voltage range, charging circuitry comprising a charging capacitor. The charging capacitor includes a higher voltage when charged than the operating voltage range. The HDD also includes pulse circuitry configured to pulse power from the charging circuitry to the write components within the operating voltage range during a controlled shut down of the write components such that remaining data-sector bits are written during the controlled shut down.

Abstract: Systems and methods for detecting touchdown of a head on a disk are provided. In one embodiment, a disk drive comprises a thermal sensor configured to sense a temperature of a head and to generate a thermal signal based on the sensed temperature. The disk drive also comprises touchdown circuit configured to receive the thermal signal, to increment a count value each time the thermal signal exceeds a thermal threshold, and to output a fault signal when the count value is equal to or exceeds a count threshold.

Abstract: A disk storage system having servo data stored thereon for accurate head position control over a magnetic or other storage medium. The servo data is seamless and untrimmed and consists of a primary servo burst set (AB burst) in which the difference defines the desired tract pitch for the surface. Multiple secondary servo burst sets (e.g., CD burst and EF burst) are written at the desired track pitch but radially offset from the primary burst set. In one embodiment, two secondary servo burst sets are used, but alternatively, any number of secondary servo burst sets could be used. In this exemplary embodiment having two secondary servo burst sets, the CD servo burst set is offset by ? of the track pitch from the primary servo burst set. Also in this embodiment, the EF servo burst set is offset by ? of the track pitch from the primary servo burst set. There are six bursts per set. The servo data is written in multiple servo sectors around the surface of the medium.

Abstract: A method for positioning a magnetic-recording head. The method includes correcting amplitude of each burst signal of a plurality of burst signals read out with the magnetic-recording head from each respective burst pattern of a plurality of burst patterns. In addition, the method includes computing a deviation of the magnetic-recording head from a track based on corrected amplitudes of the plurality of burst signals. Moreover, the method includes positioning the magnetic-recording head on the track based on the deviation of the magnetic-recording head.

Abstract: According to one embodiment, a servo pattern writing method includes: moving a head from a first one of innermost and outermost circumferences of a medium to the remainder other than the first one while controlling a position of the head in accordance with a temporary pattern preliminarily written on the medium; calculating a junction between a servo pattern to be written from the innermost circumference and a servo pattern to be written from the outermost circumference based on a movement distance of the head; first writing the servo pattern from a second one of the innermost and outermost circumferences to the junction, while controlling the position of the head in accordance with the temporary pattern; and second writing the servo pattern from the remainder other than the second one to the junction, while controlling the position of the head in accordance with the temporary pattern.

Abstract: A thin film magnetic recording head is fabricated by forming a substrate from opposing ferrite blocks which have a ceramic member bonded between them. This structure is then diced to form a plurality of columns, wherein each column has a ferrite/ceramic combination. Each column represents a single channel in the completed head. A block of ceramic is then cut to match the columned structure and the two are bonded together. The bonded structure is then cut or ground until a head is formed, having ceramic disposed between each channel. A ferrite back-gap is then added to each channel, minimizing the reluctance of the flux path. The thin film is patterned on the head to optimize various channel configurations.

Abstract: A hard disk drive (HDD) minimizes the effects of far track erasure (FTE) by counting the number of writes to the data tracks and incrementing counters based on the known effect of FTE on each track. The extent of the FTE effect is determined for each track within a range of tracks of the track being written, and based on the relative FTE effect for all the tracks in the range a count increment (CI) is determined for each track within the range. A counter is maintained for each track. For every writing to a track, a count for each track within a range of the track being written is increased by the CI value associated with the track number within the range. When the count value for a track reaches a predetermined threshold the data is read from that track and rewritten, preferably to the same track.

Abstract: A servo system according to one embodiment includes at least one servo sensor for sensing a lateral position of a magnetic head with respect to at least one defined servo track of a longitudinal tape; a fine actuator configured to translate the magnetic head laterally with respect to the longitudinal tape; a coarse actuator configured to translate the fine actuator laterally with respect to the longitudinal tape; and a servo control. The servo control is configured to perform various operations that may be used to estimate a midpoint of lateral tape excursion of a flangeless tape path for calibrating a tape drive. Additional systems are also presented.

Abstract: In one embodiment, a method includes sensing a servo sensor while a longitudinal tape is moved past a magnetic head, determining position error between the magnetic head and a desired position related to the at least one defined servo track; providing signals to operate a fine actuator to translate the magnetic head laterally in a manner to reduce the determined position error; transitioning from a write state to a monitor state when the determined position error is greater than a threshold error value; transitioning from the monitor state to a stop write state when the determined position error is greater than the threshold error value for a first predetermined period; and transitioning from the monitor state to the write state when the determined position error is less than the threshold error value for a second predetermined period.

Abstract: In an embodiment of the present invention, a disk drive comprises a head actuated over a disk including a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The read signal from the head is processed to detect a plurality of the sync marks in spiral track crossings. A plurality of timing recovery measurements are generated corresponding to the detected sync marks, and the timing recovery measurements are biased based on a radial location of the head. A servo write clock is generated in response to the biased timing recovery measurements, and the servo write clock is used to write product servo sectors to the disk.

Abstract: Methods, systems, and apparatus, including computer program products, are described for calibrating voice coil motors. In one aspect, a method is provided that includes seeking toward an outer diameter of a machine readable medium from a target servo track to a blank portion of the machine readable medium. A radial velocity of an actuator is determined after accelerating the actuator to a target radial velocity. The radial velocity is compared to the target radial velocity, and a current, that is used to controllably modify the radial velocity of the actuator if the radial velocity is different from the target radial velocity, is calibrated.

Abstract: Embodiments of the present invention provide a servo write medium, method and device for writing servo information by self servo write on the servo region formed from a flat section of the discrete track medium. The recording or write device yields the same servo characteristics as magnetic servo writing, is superior to pre-patterned servo, and delivers a greater write storage capacity with an even higher recording density. According to one embodiment, a self servo write method is used to write servo information on a flat section formed on a patterned disk on which discrete tracks are formed. Timing detection patterns (grooves) required for controlling the timing along the periphery during self servo write are formed by pre-patterning on the disk, and RRO error signals used for positioning control along the radius are written in the servo information on a flat section of the disk.

Abstract: Provided are a method, servo channel, and tape drive for determining a reference waveform used by a correlator in a servo channel. Sequences of servo signal samples are provided from read servo signals read from a servo pattern on a recording medium. A determination is made of a reference waveform based on the sequences of servo signal samples and the reference waveform is forwarded. Interpolated servo signals are generated. The interpolated servo signal samples and the forwarded reference waveform are received to generate correlation output samples. Position and velocity information are calculated from the correlation output samples.

Abstract: Provided are a method, servo channel, and tape drive for determining a reference waveform used by a correlator in a servo channel. Sequences of servo signal samples are provided from read servo signals read from a servo pattern on a recording medium. A determination is made of a reference waveform based on the sequences of servo signal samples and the reference waveform is forwarded. Interpolated servo signals are generated. The interpolated servo signal samples and the forwarded reference waveform are received to generate correlation output samples. Position and velocity information are calculated from the correlation output samples.

Abstract: A system includes an input circuit, an analog to digital converter, first and second harmonic sensor modules, a head height control module, and a weighting function module. The input circuit receives analog signals from a read/write head. The analog to digital converter generates digital samples in response to the analog signals. The first and second harmonic sensor modules determine, from the digital samples, a first magnitude of a first frequency component and a second magnitude of a second frequency component, respectively. The head height control module estimates a height of the head over a storage medium in response to a comparison of the first magnitude and the second magnitude, and selectively adjusts the height in response to the estimated height. The weighting function module applies a time domain window function to the digital samples to create modified samples on which the first and second harmonic sensor modules operate.

Abstract: An apparatus and associated method is provided for injecting a processing fluid in a device that operably rotates a disc stack. A fluid injector has a nozzle defining an outlet sized to longitudinally span the disc stack to operably direct the processing fluid toward the disc stack. The nozzle also has a flow rate feature that operably directs a first flow rate of the processing fluid from the nozzle into a space adjacent a storage surface of a first disc of the disc stack and that directs a substantially different second flow rate of the processing fluid from the nozzle into another space adjacent a storage surface of a second disc of the disc stack.

Abstract: According to one embodiment, a recording device comprises: a recording medium, an arm, a positioning module, a self-servo write clock generator, and an on-track module. The positioning module positions the arm at a position at which the electromagnetic transducer detects a rotational synchronization component of an intermediate pattern comprised in the recording medium. The self-servo write clock generator generates a self-servo write clock based on the detected rotational synchronization component. The on-track module positions the electromagnetic transducer to the intermediate pattern serving as a position for starting self-servo write based on the generated self-servo write clock. Until the on-track module appropriately completes the positioning, the self-servo write clock generator sequentially changes a decoding gate interval corresponding to the intermediate pattern in accordance with the rotational synchronization component, and captures a spiral reproduction waveform.

Abstract: A data storage circuit includes a hard disk drive (HDD) and a fall sensor. The HDD includes a rotatable media platter operable to receive and store data; a read/write head operable to communicate with the media platter by writing data to the media platter and by reading the data from the media platter; an arm supporting the read/write head; a motor coupled to the arm and operable to move the arm to and from the media platter; a drive controller operable to control the media platter, the read/write head and the servo motor; a general purpose input/output (GPIO) terminal coupled to the drive controller; and a data interface terminal coupled to the drive controller. The fall sensor is communicatively coupled to the drive controller and is configured to send an interrupt trigger signal to the drive controller when the drive is falling.

Abstract: A system and method for automatically unthreading a tape. The system and method determine whether the drive being at the stop state could cause the tape sticking condition in future after a defined dwell time (e.g., 20 minutes). The tape sticking tends to increase with time and humidity. Moreover, it is known that worn tape is stickier than new tape. With a plurality of attempts (e.g., four attempts) of moving tape (e.g., every 5 minutes), the drive is able to identify whether the tape needs to be unthreaded. Such a system allows a tape drive to handle the tape in safety at severe condition for the sticking tape, and minimize the penalty for the response to the command in normal condition.