Abstract: A method for creating a high efficiency, error minimizing code is provided. In addition, an apparatus having a high efficiency, error minimizing code is provided. In particular, the present invention provides a high efficiency, error minimizing code for use in connection with systems having a communication channel in which identifiable dominant errors occur, and that is used to transmit data that may be usefully applied in the system even though the received signal is not exactly equal to the original signal. Furthermore, the present invention provides a code that may be used to constrain the effects of dominant errors in a communication channel.

Abstract: Methods of controlling reading/writing by a read/write head of a disk drive include generating a position error signal indicative of a displacement of the read/write head from a desired radial location on a surface of a data storage disk. A control signal for moving the read/write head to the desired location is calculated responsive to the position error signal. Writing by the read/write head is inhibited responsive to the control signal exceeding a control signal threshold value. A disk drive includes a controller configured to generate a position error signal indicative of a displacement of a read/write head from a desired location on a surface of a disk, and to generate a control signal for moving the read/write head to the desired location. The controller is further configured to inhibit writing by the read/write head responsive to a predictive metric that is predictive of the position error signal exceeding a threshold.

Abstract: The present invention relates to a method of manufacturing low-density gas-filled disk drives involving test equipment utilized to determine gas leaks occurring in disk drives subjected to shock and vibration events. A disk drive is placed in a sealed container, which, in turn, is connected to a gas detection device. Following shock or vibration testing, the gas detection device determines if a leak has occurred, as well as the quality of gas leaked from the disk drive. The present invention also involves a test apparatus designed to check the accuracy and calibration of associated gas detection devices used during the shock and vibration tests. The test apparatus utilizes a sealed test chamber containing a known quantity of gas, which is released during a test event. Knowing the quantity of gas released, the output of the gas detection device can be monitored and calibrated as needed.

Abstract: A disk drive includes a rotatable storage disk, a suspension, and a slider assembly. The slider assembly includes a slider body, a first slider deformer and a second slider deformer. Activation of the first slider deformer deforms the slider body, and activation of the second slider deformer deforms the slider body. Further, the slider deformers can be independently controllable. The read element is positioned near the first slider deformer and the write element is positioned near the second slider deformer. Activation of the first slider deformer adjusts a read head-to-disk spacing of the read element and activation of the second slider deformer adjusts a write head-to-disk spacing of the write element. Further, activation of the first slider deformer does not significantly influence the write head-to-disk spacing and activation of the second slider deformer does not significantly influence the read head-to-disk spacing.

Abstract: A method and apparatus for improving servo stability in read heads while writing is disclosed. In one embodiment, a magnetic storage device includes a disk surface and a transducer. The disk surface has servo information and user data stored thereon. The transducer includes a read head and a write head. The read head is operable to read servo information and user data from the disk surface. The write head is operable to write user data onto the disk surface. The read head is biased by a first bias current when reading user data and servo information from the disk surface during a read operation. The read head is biased by a second bias current when reading servo information from the disk surface during a write operation. The second bias current, which is different from the first bias current, is selected to increase servo stability in the read head when writing. Further, the write current may also be modified from a standard value in order to increase servo stability in the read head while writing.

Abstract: Methods of controlling seeking of a transducer that is adjacent to a rotatable disk in a disk drive are disclosed. The methods may include accelerating the transducer radially across the rotatable disk from an initial track on the rotatable disk toward a destination track on the rotatable disk, estimating a deceleration switching position/velocity point, estimating a maximum deceleration position/velocity point following the deceleration switching position/velocity point, and estimating a deceleration current required to decelerate the transducer from a non-zero velocity at the maximum deceleration position/velocity point to zero velocity at the destination track. The estimated deceleration current is compared to a maximum available deceleration current, and responsive to a determination that the current required to decelerate the transducer from the maximum deceleration point to the destination track exceeds the maximum available deceleration current, the estimated deceleration switching point is adjusted.

Abstract: A filter assembly in the form of a laminated structure incorporates a breather filter section and a recirculation filter section. A hinge is incorporated in the laminated structure to allow the recirculation filter section to be moved relative to the breather filter section during installation of the filter assembly in a disk drive. A low permeability side of the breather filter section is disposed on the “environment” side of a filtering media to control access to the filtering media from the environment. A high permeability side of the breather filter section is disposed on the “drive side” of this filtering media to control access to the filtering media from within the interior of the drive.

Abstract: Various embodiments of the present invention are generally directed to processing servo data on a storage surface by detecting a time difference between consecutive read signal envelopes from spiral servo information on the surface.

Abstract: A magnetic recording medium having a soft magnetic underlayer structure that includes two soft underlayers is presented. A thick first soft underlayer, disposed on the medium substrate, is made of material which provides a low magnitude of magnetization saturation (Bsat) and high permeability. The first soft underlayer can be formed by plating or high-rate sputtering. The second soft underlayer, which has a lesser thickness than the first soft underlayer, is made of a material which provides a relatively high magnitude of Bsat and low permeability. The second soft underlayer can be formed by low-rate sputtering. The first soft under layer can be isolated from other layers in the medium by an exchange isolation layer. The second soft underlayer can be exchange coupled to a radial exchange pin layer disposed on the exchange isolation layer.

Abstract: A disk drive includes a head and a disk, spiral patterns are located on the disk, and the disk drive self-writes servo patterns on the disk using the spiral patterns as a reference for servoing the head. In an embodiment, the disk drive uses preliminary servo patterns to determine repeatable runout of the spiral patterns. In another embodiment, the disk drive reads each spiral pattern with multiple timing windows.

Abstract: A hard disk drive is disclosed comprising at least one disk rotatable about an axis, an actuator assembly moveable relative to the disk, a transducer positioned on the actuator assembly, an actuator signal line, a piezoelectric actuator element disposed on the actuator assembly and electrically interconnected to the actuator signal line, a processor, a sensor signal line and a piezoelectric sensor element for sensing a vibration. The piezoelectric sensor element is collocated with the piezoelectric actuator element and electrically interconnected to the processor by the sensor signal line. The piezoelectric actuator element is operable to move the at least one transducer relative to a surface of the disk. The piezoelectric sensor element is electrically isolated from the piezoelectric actuator element. A method for detecting a vibration in a hard disk drive actuator assembly is also disclosed.

Abstract: Techniques for reducing adjacent track erasure include: a bucking coil having a lower number of turns than the write coil for bucking out a portion of the field induced by the write coil; a hybrid solenoid coil that includes turns that are in a pancake arrangement and turns that are in a solenoid arrangement; a P2 write pole tip with an increasing amount of flare as the distance from the ABS increases; a notch along an edge of the ABS surface of the P1 write pole adjacent to a tooth that extends closest to the P2 write pole; a back notch adjacent to the tooth on the P1 write pole that has a width generally corresponding to the width of the tooth; and a layered structure on the pole tip of the P1 write pole adjacent to the tooth, the layers having at least one of decreasing amounts of saturation magnetization, decreasing amounts of permeability, or alternating layers of magnetic and nonmagnetic material, where the width of the magnetic and nonmagnetic layers in controlled or the characteristics of the magnetic

Abstract: A disk drive head stack assembly (66) of a configuration that facilitates the assembly thereof is disclosed. One or more head/arm assemblies (74) are mounted on a pivot bearing (118). This pivot bearing (118) includes a tapered section (126). Each head/arm assembly (74) may be mounted on the pivot bearing (118). Thereafter, a retainer ring (102) may be advanced relative to the pivot bearing (118). Advancement of the retainer ring (102) along the tapered section (126) expands the retainer ring (102) so that the same may be disposed within a retainer ring slot (130) of the pivot bearing (118). Each head/arm assembly (74) is maintained between this retainer ring (102) and a flange (134) of the pivot bearing (118).

Abstract: A system provided for protecting a disk drive from impact damages. More specifically, a disk drive is provided that includes an accelerometer interconnected to a printed circuit board that detects free fall of the disk drive. In addition, the velocity of spinning disks of the disk drive is also monitored to assess changes in velocity thereof that may indicate the presence of a tumbling condition. Furthermore, the change in acceleration measured by the accelerometer is monitored to prevent false indications of free fall due to common vibrations. Thus an enhanced system is provided that protects disk drives from the effect of free falls under a wide variety of conditions and allowing for drops from shorter distances to be identified.

Abstract: Methods and structures for an improved processor pipeline to eliminate the effect of correctable soft errors on processor/memory pipeline performance. Features and aspects hereof provide that the pipeline is extended by the addition of one or more information correction stages to correct a soft error using the fetched unit of information and the associated error correcting codes. By extending the pipeline, soft error correction does not stall the pipeline and hence system performance is improved in the face of soft errors from an error correcting memory subsystem.

Abstract: Various methods and apparatus are provided for merging and demerging pairs of disks. In one embodiment, pairs of merged disks are first separated and then transferred to separate cassettes such that all of the disks in the separate cassettes are oriented in the same way within the cassette. In a second embodiment, two separate cassettes of substrate disks are combined into a single cassette. The merged substrate disks may be positioned in gap merge pairs, contact merge pairs or may be equally spaced in the cassette depending upon the orientation needed for the next process.

Abstract: Methods of compensating for radial incoherence in servo information that is read from adjacent servo tracks that have a phase offset relative to one another on a data storage disk of a disk drive are provided. While a transducer is seeking to a target track, the transducer generate a servo information signal that has a first component from servo information read from a first servo track on the disk and a second component from servo information read from a second servo track that is radially adjacent to the first servo track. The servo information in the first and second servo tracks are offset by a non-zero phase error relative to one another and are in a same servo sector on the disk. The servo information signal is sampled to generate a series of sampled servo values. A phase error of a group of the sampled servo values is determined. The sampled servo values are compensated in response to the determined phase error to generate compensated servo values with at least reduced phase error.

Abstract: A disk drive includes a rotatable storage disk, an actuator motor, a slider that magnetically interacts with the storage disk, and a drive circuitry. A portion of the slider moves between a first position wherein the slider does not contact the storage disk and a second position wherein the slider contacts the storage disk. The drive circuitry can detect when the position of the slider changes between these positions. In one embodiment, the drive circuitry monitors off-track movement of the slider to detect when the slider has moved between these positions. The drive circuitry can also current that is directed to the actuator motor that is used to compensate for off-track movement to detect when the slider moves between these positions. In yet another embodiment, the drive circuitry monitors a rotational velocity of the storage disk to detect approximately when the slider moves between these positions.

Abstract: A disk drive has multiple disk surfaces and corresponding heads, each disk surface includes multiple regions, and each head is for recording on and playback of information from a corresponding disk surface. The data track density in a first region on a first disk surface is greater than the data track density in a first region on a second disk surface, the data track density in a second region on the first disk surface is less than the data track density in a second region on the second disk surface, the first regions are radially similarly situated regions and the second regions are radially similarly situated regions.

Abstract: A method and apparatus for partial self-servo writing a disk surface in a disk drive using servo wedge propagation is provided. In one embodiment, servo information is written by a servo track writer near an outer diameter of the disk surface. The servo information is grouped into a 1x set of servo information and a 2x set of servo information. The disk drive's read head is used to read the 1x set of servo information in order to position the disk drive's write head to write servo information which is radially-aligned with the 2x set of servo information. Then, the disk drive's read head is used to read the 2x set of servo information in order to position the disk drive's write head to write servo information which is radially-aligned with the 1x set of servo information. The process is repeated on a track-by-track basis until servo information is written from the outer diameter of the disk surface to the inner diameter of the disk surface, as if it was entirely written by a servo track writer.