Abstract: The maximum external magnetic field of a magnetic recording medium longitudinal component which is applied to a magnetic recording medium is smaller than an absolute value Hn of a magnetic field at the intersection of a straight line connecting two points of an M-H curve in the longitudinal direction of a soft magnetic backing layer and a tangent of the M-H curve. One of the two points is a point (Hs, Ms) at which magnetization saturates in the first quadrant. The other of the two points is a positive intersection (0, Mr) of the M-H curve and the ordinate. The tangent is at a negative intersection (−Hc, 0) of the M-H curve and the abscissa.

Abstract: A dual purpose piezoelectric element utilized in a disk drive for fine positioning of the head assembly relative to the surface of a disk and for sensing shocks and other vibrations. When a shock is sensed by the piezoelectric element that exceeds a predetermined threshold value, write operations are halted to prevent a write operation occurring at an incorrect location on the disk.

Abstract: A method for detecting head-to-disk interference events in a disk drive is provided. The invention comprises coupling a transducer to an air filter in the disk drive, wherein the transducer detects changes in magnetic readings due to debris produced by physical contact between a read/write head and a magnetic storage medium (head crash). The recirculation filter is monitored during disk drive operations and comparing magnetic readings from the transducer with defined parameters. If the transducer readings exceed the defined parameters, the spindle motor of the disk drive is shut off, thus stopping the rotation of the disk and minimizing data loss and damage due to the head crash.

Abstract: A magnetic recording and/or reproducing apparatus performing efficient decoding to lower a decoding error rate. A magnetic recording and/or reproducing apparatus 50 includes a modulation SISO decoder 63 for modulation decoding data modulation-encoded in a predetermined fashion by a modulation coder 52. In the magnetic recording and/or reproducing apparatus 50, the modulation SISO decoder 63 is a soft input soft output (SISO) type modulation decoder fed with a soft input signal and issuing a soft output signal. The modulation SISO decoder 63 is fed with a trellis soft output signal D64 supplied from a trellis SISO decoder 62 to find a soft decision value for an error correction coding data D52 fed to the modulation coder 52 of the recording system to generate a modulated soft decision signal D65. The modulation SISO decoder 63 routes the so-generated modulated soft decision signal D65 to a downstream side error correction soft decoder 64.

Abstract: A magnetic head device comprising a head section 55 for applying a magnetic field to a disk. The head section 55 includes a magnetic field generating section 61 and a slider 62. The slider 62 supports the magnetic field generating section 61 and may be set in sliding contact with the disk. The magnetic field generating section 61 has a magnetic core 63 and a coil 64 wound around the magnetic core 63. The section 61 is designed to generate the magnetic field and embedded in and formed integral with the slider 62. The head section 55 excels in heat-radiating property.

Abstract: A method for writing timing marks on a rotatable storage medium, such as on a disk in a disk drive, includes the steps of: 1) during a rotation of the disk, detecting the passage of at least a portion of a first timing mark located at a first radius of the disk, and 2) writing a second timing mark at a second radius of the disk, the location of the second timing mark being based at least in part on a stored calculation of a delay from the time of passage of the first timing mark during a rotation of the rotatable storage medium. The location of the second timing mark is calculated based on alternative time intervals between detected timing marks and on various functions of the time intervals.

Abstract: The invention relates to a method for recovering from shock event to a disk drive. Embedded servo wedges are read to generate position error signal (PES) values. The disk drive is transitioned to a write unsafe state if a PES value is greater than a write unsafe (WUS) threshold and is less than a shock detection threshold. The disk drive is transitioned to a shock recovery state if a PES value is greater than the shock detection threshold. The disk drive is transitioned from the shock recovery state to the write unsafe state if a first number of consecutively generated PES values remain less than the WUS threshold. The disk drive is transitioned from the write unsafe state to the on-track state if a second number of consecutively generated PES values remain less than the arrival threshold, which threshold is less than the WUS threshold.

Abstract: A multi-actuator disk storage device has at least two actuators respectively mounting plural product heads. Servo writing is performed using the product heads themselves. A first servo write operation is performed that includes operating a product head of the first actuator as a first clock head to generate first clock reference information for the product heads of the second actuator, which are operated as servo write heads to perform servo writing of disk areas associated with the second actuator using the first clock reference information. To servo write disk areas associated with the first actuator, a second servo write operation is performed. This operation includes operating a product head of the second actuator as a second clock head to generate second clock reference information for the product heads of the first actuator, which are operated as a servo write heads to perform servo writing using the second clock reference information.

Abstract: An impedance controlling circuit (152) is connected across an MR head (42) and has two current paths, each including a control transistor (154,156), a current path resistor (160,158), and a biasing circuit (162,164) in series. Each side of the MR head 42 is connected between a respective one of the current path resistors (158,160) and the biasing circuits (162,168). A shunt resistor (170) is connected between the control transistors (154,156) and the current path resistors (158,160) in each of the current paths. When the control transistors (154,156) are not conducting, the current path resistors (158,160) and the shunt resistor (170) shunt the MR head (42).

Abstract: A disc drive storage system and device is provided in which distortion in a drive signal due to a mismatch between a signal source impedance and a write head impedance is minimized. A write head that writes on a disc surface and a signal source that provides a drive signal to the write head are coupled by an electrical interconnect path. A connection device that minimizes the mismatch between the signal source impedance and the write head impedance is introduced in the electrical interconnect path. In addition, a method of coupling a signal source to a write head in a disc drive storage system is provided.

Abstract: A drive device having an improved capability of reproducing data is disclosed. If an error occurs during a reproducing operation, reproduction is retried after changing amplitude reference values depending on whether the recording laser power is adequate. This makes it possible for the retrying operation to successfully read data that the previous reproducing operation failed to correctly read owing to an inadequate recording laser power. The determination as to whether the recording laser power is adequate is performed on the basis of the degree of asymmetry of the waveform of a data signal read by head means.

Abstract: A magnetic write head configured for high data rate operation has first and second pole pieces, a write gap formed between the first and second pole pieces, and at least one long and narrow magnetic column extending between the first and second pole pieces which is magnetically in parallel with the write gap. The magnetic column serves as a low frequency attenuator in the magnetic write head as it shunts magnetic flux excess away from the write gap at low frequencies. Thus, the magnetic write head is configured to write data at a high data rate where a sufficient magnetic flux is produced at the write gap, and configured to write data at a low data rate where the at least one magnetic shunting element shunts magnetic flux excess so that a reduced magnetic flux is produced at the write gap. This reduced low frequency or DC magnetic flux does not exceed the maximum flux level beyond which excessive side-writing and adjacent track interference (ATI) would otherwise begin to occur.

Abstract: A method of initializing a magnetic sensor having two antiferromagnetic layers is described. The method takes advantage of the spin flop effect such that the two antiferromagnetic layers may be orthogonally initialized. The signal polarity of the sensor is well controlled.

Abstract: A technique for presenting an optimally timed control signal to an upper H-switch driver in a fashion capable of achieving a very fast transition of the current in the inductive recording head. The technique also provides a current boost during the transition while resulting in minimized power consumption at other times.

Abstract: A recording/reproducing apparatus capable of switching over among a plurality of heads with high precision, wherein the apparatus is provided with: a recording/reproducing unit for recording/reproducing signals onto/from a recording medium with a plurality of heads; a generating unit for generating control data for controlling the recording/reproducing unit; and a transmitting unit for transmitting control data generated by the generating unit to the recording/reproducing unit, wherein priority is given in transmission to data for controlling the switching of the plurality of heads over other data.

Abstract: A first clock track is written to a data storage region of a storage medium at a first position between first and second boundaries. A first set of further clock tracks is written to other positions on the data storage region, these other positions lying between the first position and the first boundary. A second set of further clock tracks is written to other positions on the data storage region, these second other positions lying between the first position and the second boundary.

Abstract: A data storage device includes a disc stack, a rotary actuator having an arm coupled to a transducer head, and support structure for receiving the arm with a reduced incidence of sliding contact therewith. The arm is separated from the support means, and then moved so that the head is above a disc surface for storing data. After the disc stack reaches its nominal rotation speed, the head is loaded so that it can transfer data. During periods of non-activity, the head is raised (unloaded) again and the arm is placed on the support means. This reduces a risk of damage in the presence of shocks while minimizing particle generation induced by friction.

Abstract: A disk drive implements a technique for improving data storage capacity of data tracks having a servo wedge defect. A servo-fault position threshold is established for aborting a write operation if a transducer head position error from a circular track centerline exceeds the servo-fault position threshold. Servo wedges having operation, the servo-fault position threshold is ignored at a tagged servo wedge thereby preventing the tagged servo wedge from aborting a write operation. The data write operation is prevented for a predetermined number of servo wedges immediately following the tagged servo wedge by skipping data wedges between the tagged servo wedge and a last servo wedge of the predetermined number of servo wedges. Data may be written to a data wedge immediately following the last servo wedge.

Abstract: The present invention may be embodied in a method, implemented in a disk drive, for analyzing a magnetic media surface for indications of rough handling or “head slap.” In the method, a media surface is scanned to detect errors indicative of media defects. Location information is recorded for each detected error. Defect clusters are identified based on the location information. A confidence factor is generated based on a comparison between the defect clusters and a representation of the physical dimensions of the head. Whether the confidence factor indicates an impact between the head and the media surface is determined.

Abstract: A scheme for ultrafast magnetization reversal in an in-plane magnetized layer (3) is disclosed. For that, an external magnetic field {right arrow over (H)}ex is applied such that the magnetization {right arrow over (M)} precesses around the external magnetic field {right arrow over (H)}ex and the external magnetic field {right arrow over (H)}ex is maintained until the precession suffices to effect the magnetization reversal. The external magnetic field {right arrow over (H)}ex is applied approximately perpendicular to the magnetization {right arrow over (M)}.