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: According to one embodiment, a magnetic disk device includes a receiver, a storage module, a determining module, and a prescanner. The receiver receives a command from a host device. The storage module stores, with respect to each of divided areas formed by dividing the recording area of a recording medium into a plurality of areas, pre-scan control information indicating at least one of the receiving time and the number of receiving times. The receiving time indicates a time at which a write command is received. The number of receiving times indicates the number of times the write command is received within a predetermined period after the power is turned on. The determining module determines the order in which pre-scan is performed on the divided areas based on at least one of the receiving time and the number of receiving times. The prescanner pre-scans the divided areas in the determined order.

Abstract: A magnetic disk apparatus includes a magnetic disk, a magnetic head, a servo reproduction signal generator and a magnetic head controller. The disk includes a data recording area and a servo-pattern area. The data recording area includes a non-magnetic area scattered with magnetic regions, and the servo-pattern area includes uniformly magnetized magnetic regions larger than the magnetic regions in the recording area. The magnetic head reciprocates radially of the disk, giving a magnetization direction to the magnetic regions in the data recording area and reading the magnetization direction of the magnetic regions in the data recording area and the servo-pattern area. The servo reproduction signal generator reads the servo-pattern area, using the magnetic head, via an absolute-value calculation circuit to generate a servo reproduction signal before the recording or reading with respect to the data recording area.

Abstract: A data storage device, that stores write data by a head, rewrites data on an adjacent track at a timing which is different from write retry of detecting a head off track when data may be written to an adjacent track. When an off track error, which affects data on an adjacent track, is generated by a write command, rewrite processing of this write command is not executed immediately, but a rewrite request including information on the track to be rewritten and the shift amount of the off track is held. And the rewrite request being held is executed at a timing which is different from the write retry. So rewrite processing can be executed after vibration, which caused the off track, stops, and the generation of an off track error during rewrite processing and the generation of further off track writing can be prevented.

Abstract: A head IC, which adjusts an amplitude level of a read signal of a head, for outputting to a read channel having an AGC amplifier, includes: a differential amplifier; an AGC circuit; external gain setting sections; and a switch. Since the AGC amplifier is disposed in the head IC, the amplitude from the head is automatically adjusted in the head IC, and the signal level, which enters the input dynamic range of the AGC amplifier of the read channel, can be adjusted. The AGC amplifier can be operated as a fixed gain amplifier using a gain value which is set from the outside, so the power consumption can be minimized even if automatic adjustment is performed.

Abstract: A magnetic disk device includes a head that reads position information, a position-information correction value for correcting the position information, and an error correcting code for the position-information correction value from a storage medium; a microcontroller unit (MCU) and an error check and correct (ECC) circuit for correcting an error in the position-information correction value based on the error correcting code; and a static var compensator (SVC) that performs position control based on either one of the position-information correction value read by the head and the position-information correction value with the error corrected by the MCU and the ECC circuit, and the position information read by the head so that the head is located at a target position on the storage medium.

Abstract: According to one embodiment, a head gimbal assembly includes: base plate body; flexure; through hole passing through the base plate body; cylindrical base that upstands from the front surface of the base plate body, and has a first inner diameter; a cylindrical flange that continues to the base around the through hole and has a second inner diameter smaller than the first inner diameter; and inner wall surface that is defined by the flange and extends along a cylindrical surface formed by a generating line parallel to a central axis of the through hole. A ratio of a thickness T of the flange defined along a virtual plane orthogonal to the central axis of the through hole to a length L of the inner wall surface defined in a direction parallel to the central axis of the through hole is set to 1.5 or less.

Abstract: A storage medium driving apparatus includes a head slider opposed to a storage medium, an acceleration detector detecting an acceleration of the apparatus. A control circuit retracts the head slider from above the storage medium according to a result detected by the acceleration detector and selectively executes one or more operations from among a plurality kinds of operations according to an index that is derived from the result detected by the acceleration detector and represents an amount of an impact energy.

Abstract: A magnetic disk device includes a swing-type head actuator which is driven by a voice coil motor. The voice coil motor is cooled by an airflow generated when a magnetic disk accommodated in a disk accommodating unit of an enclosure is rotated by a spindle motor. An airflow dividing member provided on an inner wall or a base of an actuator accommodating unit divides the airflow generated by the rotation of the disk and passing along the inner wall. The divided airflow is introduced to a coil part of the voice coil motor, and cools the coil, without sacrificing the dust purge performance.

Abstract: A head IC adjusts an amplitude level of head read signals with regard to scattering in head output characteristics, so as to conform to the input dynamic range of the read channel AGC. An AGC amplifier is provided in a head IC connected to a read channel, and the feedback response speed of the AGC circuit of the head IC is set to be substantially slower than the feedback response speed of the AGC circuit of the read channel. Within the head IC, the amplitude of signals from the head is automatically adjusted, enabling adjustment of the input signal level to the input dynamic range of the AGC amplifier of the read channel. The AGC circuit of the head IC has no effect on the faster AGC operation of the AGC circuit of the read channel.

Abstract: A magnetic disk apparatus includes a magnetic disk, a magnetic head, a reverse-pulse detector, and a re-magnetizer. The magnetic disk includes a data recording area and a servo-pattern area. The magnetic regions of the servo-pattern area have been pre-magnetized in the same direction or pre-magnetizing direction. The magnetic head is arranged to reciprocate radially of the magnetic disk. The reverse-pulse detector is provided for reading the servo-pattern area with the magnetic head before data recording or reproducing with respect to the data recording area is performed. The reverse-pulse detector detects, from servo reproduction signal pulses, reverse pulses corresponding to the reversal of magnetization direction relative to the pre-magnetizing direction. The re-magnetizer causes the magnetic head to perform the re-magnetizing of the magnetic regions in the servo-pattern area when the count of reverse pulses is not smaller than a threshold number.

Abstract: According to one embodiment, a magnetic recording device includes a write controller to control such that writing first information having a same polarity throughout the first information in a predetermined region including a plurality of tracks in a recording medium, writing second information in a target track located within or close to the predetermined region, and writing third information having, at an end of the writing, a polarity opposite to the polarity of the first information in a region of the target track in which the second information is not written, are performed; a read controller to control such that the second information is read after each of writing of the second information and writing of the third information; and a determiner to determine occurrence of pole erasing based on each second information read under the control by the read controller.

Abstract: According to one embodiment, a storage medium that stores position information indicating positions of a plurality of tracks in a radial direction in the tracks, wherein the position information includes: a first pattern in which a feed angle indicating a phase difference between the tracks is an angle obtained by adding a predetermined angle to +90°; a second pattern in which the feed angle is an angle obtained by adding the predetermined angle to ?90°; and a third pattern in which the feed angle is the same as that of the first pattern.

Abstract: A head IC adjusts an amplitude level of a read signal of a head and outputs the adjusted signal to a read channel having an AGC amplifier. A head IC includes: a differential amplifier; an AGC circuit; external gain setting sections; and a switch. The AGC amplifier is disposed in the head IC, and the amplitude from the head is automatically adjusted in the head IC. The signal level can be adjusted within the input dynamic range of the AGC amplifier of the read channel. An estimated gain value converted from a result of measuring a resistance value of the head is used as an initial value for the adjustment of the AGC amplifier. It becomes possible attempting to prevent an increase in the lock-in times of the AGC, to guarantee stability, and to prevent judgment errors of the AGC.

Abstract: According to one embodiment, an error correcting circuit includes: a marker decoder configured to sample 2-bit markers from a data string and, from a plurality of sample values of the 2-bit markers, determine whether there is an occurrence of an error on the 2-bit markers, of an insertion error, or of a deletion error; and an error correcting module configured to perform first error correction on the data string received from the marker decoder by using an error correcting code in the data string. When either one of the insertion error and the deletion error is determined to have occurred, the marker decoder is configured to perform second error correction on the either one of the insertion error and the deletion error, and output the data string from which the 2-bit markers are removed.

Abstract: A difference value between a gain control value when a head comes into contact with a recording medium and a gain control value when the head floats with respect to the recording medium by a target floating amount is stored in advance. When the information access device is actually operated, supply power to a heater is adjusted to once bring the head into contact with the recording medium, a first gain control value adjusted by a gain control section when the head comes into contact with the recording medium is obtained, a second gain control value to be adjusted by the gain control section when the head floats from the recording medium by the target floating amount is obtained from the first gain control value and the difference value, and the supply power to the heater is adjusted such that the second gain control value is supplied to a gain variable amplifier by the gain control section.

Abstract: According to one embodiment, a memory device includes: a driving module configured to store therein data on a sector-by-sector basis; a first verifying module configured to verify, during a reading operation, sector data from the driving module; a partitioning module configured to partition the sector data into sets of subsector data, a size of each set of subsector data being smaller than a size of the sector data; an appending module configured to append an error detecting code to each set of subsector data; a second verifying module configured to store, in a predetermined memory, the sets of subsector data retrieved from a buffer, and to verify the sets of subsector data using respective error detecting codes; and a sending module configured to send, from the memory, the verified sets of subsector data to the host with a transfer size.

Abstract: A heater for changing a projection distance protrusion value by thermal expansion accompanying electric-power-distributed heating is provided in a head having at least a reading element. At desired correction timing, a changed distance detection unit measures a clearance changed distance in a state in which the head is positioned to a track on the recording medium while increasing the amount of electric power distributed to the heater. A contact determination unit determines that the head is brought into contact with the recording medium when a derivative value of the clearance changed distance is below a predetermined threshold value. A measurement output unit outputs the clearance changed distance detected by the changed distance detection unit at the time of contact determination of the contact determination unit as a measurement result of the clearance between the reading element and the recording medium.

Abstract: According to one embodiment, a head suspension unit includes: a head suspension; a thin plate body of a flexure attached to a surface of the head suspension and holding an insulating layer on the surface thereof; a wiring pattern formed on a surface of the insulating layer and forming a hollow conductor defining a hollow space extending along the surface of the insulating layer; and an insulating material filling the hollow space.

Abstract: A head IC adjusts an amplitude level of a read signal of a head and outputs to a read channel having an AGC amplifier, includes an AGC amplifier. The AGC amplifier has a feedback loop control type first amplifier and a feed-forward control type second amplifier. The precision of control with respect to a target value is improved, and an AGC amplifier with fast response can be configured. Further, increases in the AGC pull-in type can be prevented, stability can be assured, and erroneous AGC judgments can be prevented.