Abstract: An optical disc device capable of detecting a reference position of an optical disc in a rotating direction includes an optical disc rotation drive unit, an optical sensor, and a control circuit. The optical disc rotation drive unit rotates the optical disc provided with a rotation reference mark. The rotation reference mark is formed into a shape having a width changing in the radial direction of the optical disc. The optical sensor detects the rotation reference mark. The control circuit controls the optical disc rotation drive unit and the optical sensor, extracts a detection signal of the rotation reference mark as a pulse waveform from an output signal of the optical sensor with the optical disc being rotated, and specifies a rotation reference position of the optical disc in accordance with the pulse waveform.

Abstract: According to one embodiment, there is provided a disk device including a head, a disk, a first motor, and a first circuit. The disk has a recording surface. The first motor causes the head to seek along the recording surface. The first circuit can switch between a first state and a second state. The first state is a state where a current path of the first motor is electrically cut off from a first electricity storage unit. The second state is a state where the current path of the first motor is electrically connected to the first electricity storage unit.

Abstract: A data storage device is disclosed comprising a non-energy assist (NEA) head configured to access a first disk surface, and an energy assist (EA) head configured to access a second disk surface. The data storage device further comprises control circuitry configured to write data to the first disk surface, and migrate at least part of the data to the second disk surface.

Abstract: A data storage device is disclosed comprising a first head connected to a distal end of a first actuator arm, a second head connected to a distal end of second first actuator arm, a first coupler configured to couple the first actuator arm to an actuator, and a second coupler configured to couple the second actuator arm to the actuator. Access commands stored in a command queue are sorted into an execution order based on a selective coupling of the first and second actuator arms to the actuator. At least one of the access commands is executed based on the execution order in order to access at least one of a first and second disk surfaces using at least one of the first and second heads.

Abstract: According to one embodiment, there is provided a hard disk drive including a first recording surface, a second recording surface, a first magnetic head, a first actuator and a second actuator that move the first magnetic head, a second magnetic head, a third actuator and a fourth actuator that move the second magnetic head, a fifth actuator that moves the second actuator and the fourth actuator, a drive circuit that implements at least one of a first mode in which the second actuator and the fourth actuator operate differently from each other or a second mode in which the first and third actuators operate differently from each other, and a controller that controls the drive circuit.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a head including a first write head and a second write head configured to write data to the disk and a read head configured to read data from the disk, and a controller configured to write write data to a first area of the disk with the first write head and to overwrite the write data written with the first write head in the first area with the second write head.

Abstract: A magnetic recording cartridge is provided and including a magnetic recording medium, wherein an average thickness of the magnetic recording medium tT is 3.5 ?m?tT?5.6 ?m, a dimensional change amount ?w in a width direction of the magnetic recording medium with respect to a tension change in a longitudinal direction of the magnetic recording medium is 700 ppm/N??w?20000 ppm, the magnetic recording medium is accommodated in a state of being wound around the reel in the cartridge case and (a servo track width on an inner side of winding of the magnetic recording medium)—(a servo track width on an outer side of winding of the magnetic recording medium)>0 is satisfied, and a squareness ratio measured in a vertical direction of the magnetic recording medium is 65% or more.

Abstract: A data storage device is disclosed comprising an actuator configured to actuate a head over a disk surface, and a vibration sensor configured to generate a vibration signal (VS). Control circuitry comprising a servo control system having a torque rejection curve (TRC) configured to control the actuator is configured to measure a position error signal (PES) of the head, and measure the VS output by the vibration sensor. A feed-forward compensator is configured based on PES/VS/TRC. While seeking the head across the disk surface, the VS is processed using the feed-forward compensator to generate a feed-forward compensation during a settle interval of the seek, and the actuator is controlled using the feed-forward compensation during the settle interval.

Abstract: A cartridge memory used for a tape cartridge includes: a communication unit that communicates with a recording and reproducing device using a wireless communication method defined by an ISO 14443-2 standard which is a wireless communication standard; a non-volatile memory with a storage capacity exceeding 16 KB; and a control unit that writes or reads data to or from the non-volatile memory on a word-by-word basis (2 bytes at a time) or on a block-by-block basis (32 bytes at a time). The non-volatile memory includes a plurality of memory banks each having a storage capacity of 128 KB or less. The control unit writes or reads data defined by a magnetic tape standard to or from one or two or more first memory banks among the plurality of the memory banks, and writes or reads additional data to or from one or two or more second memory banks other than the first memory bank.

Abstract: A write head includes an input coupler configured to receive light excited by a light source. A waveguide core is configured to receive light from the input coupler at a fundamental transverse electric (TE00) mode. The waveguide core has a first straight portion. The waveguide core has a mode converter portion comprising a branched portion extending from the first straight portion. The mode converter portion is configured to convert the light to a higher-order (TE10) mode, the mode converter portion spaced apart from the input coupler. The waveguide core has a second straight portion between the mode converter portion and a media-facing surface. The write head has a near-field transducer at the media-facing surface, the near-field transducer receiving the light at the TE10 mode from the waveguide and directing surface plasmons to a recording medium in response thereto.

Abstract: The present disclosure describes aspects of constant-density writing for magnetic storage media. In some aspects, a constant-density writer delays transitions between bits within write data to enable constant-density writing. The write data has an initial bit period based on a constant clock signal, which is generated based on the rotation of a media disk. The constant-density writer modifies the write data to generate phase-delayed write data, which has a bit period that is greater than or equal to the initial bit period. To realize this bit period, the constant-density writer changes write phases of bit transitions within the write data. The constant-density writer can also insert stretch bits, filter single-bit transitions, and mitigate glitches within the phase-delayed write data.

Abstract: A data storage device includes a first data storage surface and a second data storage below the first data storage surface. The data storage device also includes a first micro-actuator coupled to a first arm that supports a first head over the first data storage surface, and a second micro-actuator coupled to a second arm that supports a second head over the second data storage surface. The data storage device further includes a coarse actuator, to which the first and second arms are coupled, that positions the first head and the second head between corresponding first and second tracks on the respective first and second data storage surfaces. Micro-actuator drive circuitry finely positions the first head over the first track and the second head over the second track by concurrently driving the first micro-actuator and the second micro-actuator in opposite directions.

Abstract: According to one embodiment, a magnetic disk device includes a disk including a first region and a second region different from the first region, a head that writes data on the disk and reads data from the disk, an actuator that positions the head on the disk, and a controller which positions the head by driving the actuator and writes data in the first region and the second region with the head, a skew angle of the head with respect to a circumferential direction of the disk varying within a first angle in the first region, and varying, in the second region, from a second angle larger than the first angle to a third angle larger than the first angle and the second angle.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a head which writes data to the disk and reads data from the disk, and a controller which executes, in a first region segmented in a radial direction of the disk, at least one of conventional recording processing which writes a plurality of tracks with a space in between in the radial direction at a first linear recording density and shingled recording processing which writes a plurality of tracks on top of one another in the radial direction at a second linear recording density which is less than or equal to the first linear recording density.

Abstract: Disclosed herein are magnetic recording devices and methods of using them. A magnetic recording device comprises a main pole extending to an air-bearing surface (ABS), a trailing shield extending to the ABS, a write-field-enhancing structure disposed between and coupled to the main pole and the trailing shield at the ABS, a write coil configured to magnetize the main pole, a write current control circuit coupled to the write coil and configured to apply a write current to the write coil, wherein the write current comprises a write pulse, and a bias current control circuit coupled to the write-field-enhancing structure and configured to apply a bias current to the write-field-enhancing structure, wherein the bias current comprises a driving pulse offset in time from the write pulse by a delay, wherein the delay substantially coincides with an expected magnetization switch-time lag of a free layer of the write-field-enhancing structure.

Abstract: A methodology that enables, for example, tape drive operation at lower SNR and/or reduced rewrite area uses a first threshold T and a second threshold r for a rewrite condition. Codeword interleaves (CWIs) in a data set are written onto a plurality of simultaneously-written parallel tracks of a magnetic recording medium, read back and error correction decoded. A determination is made as to whether at least one of the C1 or C1? codewords in each decoded CWI contains more byte errors than the second threshold r of the rewrite condition. A number of CWIs in a rewrite buffer are according to the following criteria: bi?=bi?T when bi is greater than the first threshold T, and bi?=0 when bi is less than or equal to the first threshold T.

Abstract: According to one embodiment, a magnetic disk device includes a base that includes a bottom wall and side walls standing along a circumference of the bottom wall, a housing that includes a cover facing the bottom wall and closing the base, an actuator assembly that is housed inside the housing and is rotatable around a rotation axis, a head movably supported by the actuator assembly, a control circuit board provided outside of the housing, a first sensor disposed on the control circuit board, and a second sensor disposed inside the housing.

Abstract: According to one embodiment, a magnetic disk device includes a first actuator which actuates a magnetic head portion including a magnetic head, a second actuator which adjusts a position of the magnetic head on a magnetic disk in a radial direction of the magnetic disk, and a control portion which determines a second measurement signal amplitude when a second transfer function is measured in accordance with a first gain estimated value of the second actuator and an amplitude of a first measurement signal amplitude to the second actuator applied when a first transfer function is measured, which calculates a second gain estimated value of the second actuator based on the first transfer function and the second transfer function, and which updates the first gain estimated value, using the calculated second gain estimated value.

Abstract: A magnetic tape and servo elements of a magnetic head for reading and writing to the magnetic tape can ascertain servo band signals from different servo bands that are vertically aligned and adjacent to one another. When operating in a write or read mode, at least two servo elements can be activated to respond to a write/read operation based on a determined position across a width of the servo bands in the magnetic tape. The determined position is based on various pattern combinations from different servo band identifiers from the servo band signals.

Abstract: Technologies are provided for partially updating shingled magnetic recording (SMR) zones in SMR storage devices. An SMR storage device can receive and process a command to update a write pointer for an SMR zone to point to an arbitrary write position within the SMR zone. A partial SMR zone update command can be received and processed to modify part of the data stored in the SMR zone. A write position within the SMR zone where data to be modified is stored can be identified. Data stored in the SMR zone following the identified write position can be read to a temporary location and modified. A write pointer for the SMR zone can be updated to point to the identified write position. The modified data can then be written to the SMR zone, starting at the write position identified by the write pointer, or to another SMR zone of the storage device.