Abstract: A disc certification process, apparatus and article of manufacture for improved testing efficiency employs a testing head having a write element and a read element supported adjacent a rotating disc recording surface. The write element has a width that defines a "wide" write track width of at least N times the read track width defined by the width of the read element, wherein N is an integer greater than 1. The write element writes a signal onto the recording surface of the disc during a first disc rotation, to define a first annular write track having a "wide" first write track width in the radial direction of the disc. Then, during a second rotation, the read element reads the signal written in a first reading track width defined within the "wide" first write track. Thereafter, the read element is stepped to another read position adjacent the first write track and the read element reads the signal written onto the recording surface in a second reading track width defined within the first write track.

Abstract: A fiber rolling mechanism is provided to rotate a single optical fiber along its axis so as to align markers placed in the fiber to other fiber's relative markers.

Abstract: A data symbol sequence detector for choosing data symbol sequences likely to be represented by corresponding sequences of samples received by the detector with these sample sequences formed by sampling data signals obtained from magnetically stored data through a data retrieval channel which asymmetrically affects the magnitudes of the data signals. An expected sample value estimator provides estimated expected magnitude values for a selected set of samples in the sequence, and a magnitude difference determiner is used for obtaining representations of differences between values of the samples in the sequence and the corresponding estimated expected values. These differences representations can be limited in algebraic form.

Abstract: A digital peak detection system digitizes analog signals and provides absolute values to a series of one cycle delays, and to a sequence of comparator stages. Each digital sample is parallel compared to a number of preceding samples equal to the number of active comparator stages. Control signals activate comparator stages to determine sample comparison window length, including lengths exceeding the number of samples between recorded peaks. Peak detection is optimized using a variable gain amplifier whose gain is updated based upon amplitude difference between actual and desired peak samples. When sample amplitudes are smaller than a qualifier threshold, a countdown timer increases amplifier gain after lapse of a programmed time without detecting a qualified pulse. Gain is also updated when the analog to digital converter saturates. Initial gain values can be programmed, and gain stored at the end of a servo mode for future use in reducing gain control loop convergence time.

Abstract: Solvent-free lubrication of thin film magnetic media, such as magnetic discs, is implemented by applying collimated and/or non-collimated beams of lubricant molecules, including polymeric lubricants having a known and narrow molecular weight distribution to selected regions of the media surface, such as the landing zone. Embodiments include providing in-situ and on-demand fractionation of polymeric lubricants.

Abstract: A magnetoresistive element has a height that extends from the air-bearing surface of a head. The height is determined by a slot in the head extending from the air-bearing surface adjacent the sensor portion at an acute angle to both the air bearing surface and the height of the magnetoresistive element to separate the magnetoresistive element into the sensor portion and a dormant portion. Alternatively, the height is determined by a recess of design depth in the magnetoresistive element at the air bearing surface. Alternatively, the height of the magnetoresistive element is determined by a stepped thickness to the first and second bias current carrying contacts along the height of the magnetoresistive element.

Abstract: An optical data storage system includes an optical disc which stores information in optically readable format on a data surface. A slider is provided proximate the data surface of the optical disc and is coupled to an actuator for selectively positioning the slider relative to the data surface. A Solid Immersion Lens couples to the slider and is arranged to couple light to the data surface of the optical disc. The Solid Immersion Lens is non-hemispherical.

Abstract: Head disc interference is detected and analyzed using the standard deviation of read back signal frequency. First, the amount of longitudinal head oscillation affecting transducer read/write heads located in the hard drive is measured. Measuring the longitudinal head oscillation is achieved by determining the degree of frequency modulation associated with the read-back signal as compared with a constant frequency used to write the information. Second, this measured amount of oscillation is compared to a predefined threshold value. Finally, a head disc interference alarm is activated when the oscillation is greater than the defined threshold value.

Abstract: Disclosed is a perfluoropolyether (PFPE) lubricant comprising less than about 10 percent PFPE molecules having a molecular weight lower than about 2000 Daltons, and wherein the average molecular weight of the lubricant is greater than about 5000 Daltons. Such a lubricant comprises less than about 15 percent PFPE molecules having a moleuclar weight greater than about 10,000 Daltons. Also disclosed is a thin film magnetic disc comprising a recording surface and a PFPE lubricant in contact with the recording surface. The recording surface of such a thin film magnetic disc can be adapted to magnetically record information via an air bearing read/write head. The recording surface can be smooth. The disc can further comprise a rough-surfaced landing zone inward of the recording surface, wherein the PFPE lubricant is in contact with the landing zone. Also disclosed is a method of lubricating a thin film magnetic disc.

Abstract: A scanner in a helical tape drive is calibrated to read a plurality of data track groups recorded on a tape via a servoing system controller that monitors a scanned signal, detects an offset region for an appended group of tracks, calibrates the scanner to the appended group of tracks, stores alignment data associated with the calibration in a local memory, and re-scans the group of tracks by configuring the tape drive's servoing system in accordance with the stored alignment data for the appended group of tracks. The alignment data for a plurality of appended groups on the tape can be stored and later retrieved from the local memory and used within the servoing system controller to quickly align the scanner to the appended group of tracks without having to recalibrate the scanner to each of the appended groups during subsequent read operations.

Abstract: A method of implementing a model based servo controller in a digital signal processor in a disc drive includes obtaining matrices for a discrete-time state-space realization of the servo controller. Controller states of the controller are scaled to reduce a worst case bound on the controller states. The controller states are transformed to a desired format which reduces a number of required mathematical operations. Further, the matrices are converted to fixed point format.

Abstract: A disk drive in which a movable latch locks the data transducer assembly to prevent movement due to shock. The movable latch cooperates with an actuator by engaging an actuator extension arm. The movable latch also engages a stationary magnet with one of two latching magnets. The movable latch arm is mounted to a shaft which extends into a sealed casing which incorporates a plunger. The plunger is located in a chamber filled with viscous fluid which is not subject to migration or outgassing from the chamber. The viscous fluid provides resistance to sudden movements of the plunger. Latch release is achieved by application of low continuous force to the actuator arm by a voice coil motor.

Abstract: The invention uses piezoelectric sensors to test disk drives. Both contact start-stop and load-unload type disk drives may be tested. A piezoelectric sensor is affixed to a disk drive to test for disk drive mechanical integrity. One method of affixing the sensor to the disk drive is using a mechanical clamp. The clamp is intended for repeated use on many disk drives, and therefore its easy removal is important. An alternative clamping apparatus is a magnetic clamp. In use, the clamp affixes the piezoelectric sensor to a disk drive in an optimal location with optimal force. Affixed piezoelectric sensors are used to detect aberrant behavior generated by non-optimal disk drive performance. The clamp/sensor combination detects acoustic signal in a disk drive which is used to determine whether or not a disk drive has adequate head-disk clearance. The apparatus is flexible, allowing testing after assembly of head-disk assembly and before or after servowriting and final disk drive assembly.

Abstract: An apparatus and method are disclosed for improving data recovery operations in a disc drive employing a redundant sync data block format. The disc drive includes a rotatable disc and a controllably positionable head which is used to store user data in a plurality of data blocks on tracks of the disc. Each data block includes a user data field to store user data, a first sync field and a redundant, second sync field, the sync fields storing first and second sync words, respectively, which establish symbol boundaries used by a read channel of the disc drive. User data are recovered from a selected data block by initiating a delay of selected duration during which a first portion of the selected data block passes proximate the head, allowing the second, remaining portion of the selected data block to be read at the completion of the delay.

Abstract: A bottom shield for use in a magnetic read head is disclosed. The bottom shield has a ferromagnetic layer that has a length and an outer width. The ferromagnetic layer has a first edge, a second edge opposite the first edge, and an air bearing surface. The first edge and the second edge are each normal to the air bearing surface. A plurality of notches are located along both the first edge and the second edge. The plurality of notches form a plurality of narrow widths that are each narrower than the outer width so that one of a plurality of magnetic domain walls is located at each of the plurality of narrow widths.

Abstract: An apparatus and method for automatically correcting the dynamic imbalance of a disc pack of a disc drive, the disc pack conveyed to a first selected position in a balance correction assembly station where a rotary positioner lifts and rotates the disc pack to a reference position for the attachment of weighted shims to the disc pack. A shim selector assembly delivers a selected shim, and an end effector transfers the selected shim to a shim attachment assembly. The shim attachment assembly rotates and spreads open the shim so that the disc pack can be receivingly engaged thereby, and the shim attachment assembly releases the selected shim to lockingly engage the disc pack. A flipping assembly reverses the disc pack for placement of another selected shim to the other end of the disc pack, as required.

Abstract: A tape drive for accommodating tape cartridges of different sizes and capacities is provided with a tape insertion opening, a first guide at a first side of the tape insertion opening, and a second guide at a second side of the tape insertion opening. The first and second guides are separated from one another to provide a first opening width that accommodates insertion of tape cartridges of a first size between the first and second guides. The first and second guides are movable within the tape insertion opening to provide a second opening width that accommodates insertion of tape cartridges of a second size.

Abstract: A jacket for holding and retaining a disk drive unit in a computer device bay. The jacket protects the disk drive unit from damage during handling, use and storage. The configuration of the jacket permits electrical and electrical ground coupling of the disk drive unit to a computer device bay. The configuration of the jacket also permits engagement with a retaining mechanism in the computer device bay, and permits ejection from the computer device bay without imparting an excessive shock load to the disk drive unit.

Abstract: A water or aqueous soluble salt of a perfluoro polyether alcohol is applied to form a lubricant topcoat on a magnetic recording medium. Suitable soluble salts include the sodium salt of a perfluoro polyether diol.

Abstract: A magnetic recording medium is formed with a laser textured glass or glass-ceramic substrate. The use of a pulsed, focused laser light beam, such as a CO.sub.2 derived laser light beam, enables the formation of an accurately textured landing zone on a glass or glass-ceramic substrate which is substantially replicated on subsequently applied layers.