Abstract: A disk drive may include a disk, a head actuated over the disk, a spindle motor comprising a plurality of windings and operable to rotate the disk and coupled to a first and a second spindle driver, the first and the second spindle driver coupled in parallel to the plurality of windings. The disk drive further includes one or more processing devices that are configured to detect a BEMF signal corresponding to a velocity and/or a position of the spindle motor, control, based on detecting the BEMF signal, commutation of the plurality of windings of the spindle motor using the first and the second spindle driver, and wherein the plurality of windings are commutated at or near the same time or in a sequential manner during one or more of a spin up and a spin down routine of the spindle motor.

Abstract: A data storage device includes a laser diode that heats an area of a disk near the read/write head. To mitigate mode hopping, the laser diode is preheated using the laser diode itself, such as by applying a reverse bias to the laser diode, during an interruption in writing of data to the disk. The laser diode is preheated to a temperature that maintains operation of the laser diode within a middle portion of a preselected gain mode and away from abrupt shifts in gain modes.

Abstract: A heat-assisted magnetic recording head comprises a near-field transducer (NFT). The NFT comprises a near-field emitter configured to heat a surface of a magnetic disk, and a hybrid plasmonic disk. The hybrid plasmonic disk comprises a plasmonic region and a thermal region. The plasmonic region comprises a first material or alloy that is a plasmonic material or alloy. The thermal region comprises a second material or alloy that is different than the first material or alloy.

Abstract: The present disclosure generally relates to a tape drive. The tape drive comprises a first tape head and a second tape head linearly aligned with one another, where the first tape head and the second tape head are configured to concurrently operate. The first tape head and the second tape head each comprise a plurality of write transducers, a plurality of read transducers, and a plurality of servo transducers. The tape drive further comprises a first actuator coupled to the first tape head and a second actuator coupled to the second tape head. The first and second actuators are configured to independently tilt and move the first and second tape heads, respectively. Tilting and moving the first and second tape heads individually enables the tape drive to compensate for non-linear tape dimensional stability effects.

Abstract: Example channel circuits, data storage devices, and methods for data read synchronization from phase modulated synchronization fields are described. A data synchronization detector may receive an oversampled digital read signal read from a synchronization field that uses a single written pattern to encode the start of data position, phase, and gain for the read channel. The write pattern may use a phase modulated carrier signal to encode a pseudo-random binary sequence indicating the start of data position.

Abstract: A solution for providing laser mode hop detection in hard disk drives can include a first circuit to provide a signal having a step voltage whose amplitude is adjustable according to a first control signal. The solution can include a second circuit causing the signal to be delayed by a time period to produce a delayed signal, the time period adjustable according to a second control signal. The solution can include a filter to receive the delayed signal as input and provide as output an offset signal corresponding to a frequency response a sensor. The system can subtract the offset signal from a sensor signal of a sensor to provide an output.

Abstract: Illustrative aspects are directed to a data storage device, comprising disks, an actuator mechanism configured to position heads proximate to the disks, and processing devices, including a memory. The processing devices are configured to: receive data with an indicated address for writing the data to a selected disk; read, from the selected disk, a data sector from a location that comprises the indicated address; integrate the received data with a subset of the sector read from the selected disk, thereby generating a new sector that comprises the received data positioned in the new sector in accordance with the indicated address; detect, while the new sector is in the memory and not yet written to the selected disk, a loss of nominal electrical power to the data storage device; and write, in response to detecting the loss of nominal electrical power, the new sector from the memory to a non-volatile cache.

Abstract: A solution can detect an HDD laser mode hop within an improved response time using a sensor amplification circuitry balanced by a frequency response of a gain stage circuit. A sensor of a first circuit can receive an optical signal of a laser as input and output a first voltage that an amplifier can amplify to produce an amplified first voltage indicative of a mode hop event trailing the optical signal by a first response time of a first frequency response. A second circuit coupled in series with the first circuit and operating according to a second frequency response an inverse of the first frequency response can receive the amplified first voltage and generate, based at least on the amplified first voltage adjusted by the second frequency response, a second voltage indicative of the mode hop event within a second response time that is shorter than the first response time.

Abstract: A system for determining a fly height includes a first head of a disk drive, a second head of the disk drive, a capacitive sensor circuit coupled to the first head and the second head, and a logic device coupled to the capacitive sensor circuit. The capacitive sensor circuit is configured to measure a first capacitance between the first head and the first disk, remove noise from the first capacitance using a second capacitance between the second head and the second disk, and based thereon determine a corrected first capacitance. The logic device is configured to determine the fly height between the first head and the first disk using the corrected first capacitance.

Abstract: Methods, data storage devices, and computer-readable media for setting the flying height of a recording head are disclosed. A method may set a value of a control parameter of the recording head to force a predetermined location of the recording head to be a touchdown location. The method may involve incrementally moving the recording head toward a surface of a recording media, and, using a temperature sensor of the recording head, detecting an onset of touchdown at the touchdown location as the recording head is incrementally moving toward the surface of the recording media. The method may set the fly-height control power by backing off from an initial fly-height control power value, which may be a sum of a power level at which the onset of touchdown at the touchdown location was detected and a power corresponding to the value of the control parameter.

Abstract: A phono cartridge transmission line impedance matching system is provided. The phono cartridge transmission line impedance matching system comprises a connecting port adapted for being connected to a signal line and a ground line of a phono cartridge transmission line. A capacitance switching circuit is connected to the signal line and the ground line in a parallel fashion. The capacitance switching circuit is adapted for selectively switching between different capacitances. A plurality of resistance switching circuits, connected with each other in a serial fashion, are connected to the signal line and the ground line in a parallel fashion. Each resistance switching circuit is adapted for selectively switching between different resistances.

Abstract: The present disclosure generally relates to a magnetic recording device comprising a magnetic recording head. The magnetic recording device comprises a write head and a read head. The write head comprising a trailing shield, a main pole, and a leading shield, and the read head comprises a first shield, a second shield, and a magnetic sensor disposed between the first and second shields. In some embodiments, a shield is disposed between the leading shield and the first shield. A central axis of the write head is aligned with a central axis of the read head. The read head is spaced a distance of about 5 ?m to about 20 ?m from the write head such that the magnetic recording head is controllable to write data to a media using the write head and read verify the data using the read head.

Abstract: A method, in accordance with one aspect of the present invention, includes writing, by a tape drive, data tracks to a data band of a magnetic tape having servo bands flanking the data band, the writing being performed using a magnetic head that is not designed for a format of the magnetic tape. An effective pitch of servo readers of the magnetic head used simultaneously during the writing matches a servo reader pitch specification of the format of the magnetic tape. An average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape.

Abstract: Spot size converter (SSC) in a HAMR magnetic recording head assembly have a plurality of split assist core structures. Each split assist core structure includes multiple assist cores and a main waveguide. Each split core may also include one or more side waveguides such that the main waveguide is sandwiched between the side waveguides and top and bottom assist cores. Adjacent split assist core structures, may share assist cores. The split assist core structures reduce light source power utilized to write data to magnetic media.

Abstract: A seek operation of a first actuator in a multi-actuator drive is modified, so that one or more disturbance-generating portions of the seek operation do not adversely affect operation of a second actuator in the drive. Radial motion of the aggressor actuator is controlled by limiting a slew rate of the first actuator during one or more portions of the seek operation to be less than or equal to a threshold value. Because slew rate of the first actuator is the rate of change of radial acceleration of the aggressor actuator with respect to time, limiting the slew rate of the first actuator prevents or reduces mechanical disturbances caused by jerk associated with motion of the first actuator.

Abstract: A data storage device or disk drive may include a plurality of regulators, a first voltage rail associated with a first regulator of the plurality of regulators, a second voltage rail associated with a second regulator of the plurality of regulators, wherein a switching frequency of the second regulator is greater than a switching frequency of the first regulator, the first voltage rail is associated with a higher voltage than the second voltage rail, or a combination thereof. The data storage device may include one or more processing devices configured to: determine a minimum switching frequency, identify a start time of a switching cycle for the first regulator, based at least in part on determining the minimum switching frequency; and, at or near the start time of the new switching cycle, couple the first regulator to the second regulator to initiate the switching cycle.

Abstract: An optical memory includes a support and nanoparticles, each of which changes between a crystal phase and an amorphous phase when irradiated with light. The nanoparticles are supported by the support and spaced apart from each other in one or both of an in-plane direction of a face of the support and a direction normal to the face of the support.

Abstract: A hard disk status testing apparatus, including: a voltage reading module, a controller, an analogue switch, and multiple hard disk slot units. Each hard disk slot unit includes: a hard disk status testing module and a hard disk status indication module. The hard disk status testing modules and the hard disk status indication modules among different hard disk slot units are time-multiplexed, achieving independent control of the hard disk status testing modules of different hard disk slot units and independent control of the hard disk status indication modules of different hard disk slot units. A hard disk status testing method that effectively solves the problem of an increase in the number of pins needed for hard disk status testing and status indication, thus effectively decreasing hardware costs and increasing the utilization rate of pin resources.

Abstract: A servo pattern recording method includes: determining a first servo band group that includes three or more servo bands for recording a servo pattern in which first servo band identification information having a plurality of bits is to be embedded, and a second servo band group that includes three or more servo bands for recording a servo pattern in which second servo band identification information having a plurality of bits is to be embedded, the second servo band identification information being different from the first servo band identification information; and recording the first and second servo band identification information on the first and second servo band groups, respectively, such that a combination of a first pair and a second pair is not duplicated, the first pair being a pair of servo band identification information and a phase in one servo band read by a first servo read head, the second pair being a pair of servo band identification information and a phase in the other servo band read by a s

Abstract: In response to a rotation of timing-based servo (TBS) patterns of a first servo band and a second servo band, heights of top and bottom portions of servo stripes of servo frames of the TBS patterns are adjusted to compensate for changes in a usable height of the servo stripes caused by the rotation.