Abstract: Servo data, distinguishable by phase, are stored in concentric servo tracks on a magnetic information storage disk. Each servo track includes a plurality of one type of servo pattern, with consecutive tracks arranged in a repeating sequence of the servo pattern types. For phase recognition, the pattern types further are arranged in a repeating sequence of angular sectors, each sector having a plurality of servo patterns. The servo patterns in a given storage track thus are always angularly offset from the servo patterns in the tracks adjacent thereto, permitting the use of servo patterns radially dimensioned to be greater than the separation distance between adjacent tracks, thereby increasing servo signal reliability and transducer dynamic range.

Abstract: An improved disk drive unit is provided for use in microcomputers such as personal computers and the like. The disk drive unit includes a substantially sealed disk drive housing and related circuit board with drive electronics carries by a common rigid chassis. A power connector plug is securely mounted onto the chassis at a rear margin thereof and cooperates with one or more interface connectors to permit simple slide fit installation of the disk drive unit into a computer system cabinet, such as a central processor unit for a computer. In addition, the disk drive unit includes improved shock mounts for supporting the sealed disk drive housing from the rigid chassis. The disk drive unit further includes a floating bushing arrangement for interconnecting the circuit board to the disk drive housing in a manner substantially isolating thermal expansion characteristics of the circuit board from the remainder of the disk drive unit.

Abstract: An improved spindle motor is provided for rotatably driving one or more memory storage disks in a computer disk drive or the like. The spindle motor comprises a stator shaft having opposite ends anchored to a disk drive housing, and a cylindrical rotor hub supported by bearings from the stator shaft for relatively high speed rotation. The stator shaft carries an armature in magnetically coupled relation with a high strength unitary permanent magnet sleeve carried by the rotor hub, with the number of armature poles and permanent magnet poles being mismatched to achieve low cogging motor operation. The memory disks have central openings therein and are mounted about the rotor hub for rotation during motor operation.

Abstract: A microprocessor is used to measure the performance of a disk drive during each seek operation. By measuring track crossings per unit time of acceleration the deceleration of the servo arm can be delayed as long as possible to minimize unproductive access time. A performance ratio is calculated for each seek and the look-up table values of worst case performance are modified to fit measured actual performance values.

Abstract: A vertically recording write probe and read ring head. A ring pole is mounted adjacent a vertical recording probe pole. The ring pole tip is made thin such that it saturates on write and does not affect performance of the probe pole. The ring pole tip is separated from the probe tip by a small read gap. The probe pole and ring pole are connected in a back gap region so that the combination reads like a conventional read head.

Abstract: An elongated magnetoresistive sensor strip longitudinally biased to maintain a single domain sense region by exchange-biasing material atomically coupled to the strip at the ends of the strip outside of a central sense region.

Abstract: Methods and apparatus are disclosed which utilize isotropic/perpendicular medium for performing high density digital magnetic recording. According to the preferred embodiment of the invention, the l's of a binary code are deeply imprinted on the medium by switching off the current in the winding of a magnetic ring head. The l's so imprinted on the medium are each represented by a copy of a part of the fringing field of the ring head. Each imprinted field has the appearance of a "horseshoe" pattern of magnetization. During readback these imprinted patterns correlate extremely well with the sensitivity function (the fringing field) of the ring head/readback transducer. The invention utilizes this inherently present correlation, together with a combination of longitudinal and vertical recording techniques, to provide methods and apparatus well suited to locate signals buried in noise and yield improved overall readback performance in a high density environment.

Abstract: A support means is disclosed for mounting an integrated circuit chip preamplifier with respect to an aluminum transducing head support arm in a magnetic disc drive. The support means includes two heat shields, each with an aluminum foil layer facing the preamplifier and a thermally insulative adhesive layer facing the rigid arm. The preamplifier is secured to the foil layer of the most adjacent heat shield with an electrically insulative but thermally conductive adhesive. The alternating thermally conductive and thermally insulative layers interfere with longitudinal heat transfer but allow lateral heat transfer to promote heat dissipation laterally outwardly of the support means, and thus substantially reduce thermal expansion of the support arm.

Abstract: On-the-fly error correction is provided by using the remainder from division of the encoded codeword by its generator polynomial to look up error values and locations in a memory. Alternatively, the syndromes are so employed. The values in the memory are predetermined and preassociated with each remainder or syndrome set. Alternatively, syndrome S.sub.0 directly yields the error value.

Abstract: A phase lock loop includes a phase shift apparatus to provide a plurality (i.e., four) phase-shifted clock signals from the VCO. A phase selector is responsive to a triggering signal from a one-shot multivibrator to select the one phase-shifted clock signal next following termination of the trigger signal. The one-shot is responsive to a change between the read and write mode to initiate operation of the phase selector. As a result, the initial phase error between the input signal (read pulses or write clock) and the clock signal of the phase lock loop is no more than 1/8 window.

Abstract: Runout in a rigid magnetic disk is reduced by sandwiching a sized shim between the disk and disk support to form a substantially smooth sinusoidal circumferential profile to the disk. A method of determining shim size is also described, employing test disks for determining optimal shim size for each class of rigid disk.

Abstract: A disk pack spacer ring has formed thereon a plurality of pairs of intercommunicating scoop/pump channels which prevent formation of solid body rotation of air between closely spaced disk surfaces so that the entire space between the disk surfaces is ventilated. A scoop channel angled into the direction of rotation scoops air into the channel, and a intercommunicating pump channel angled away from the direction of rotation pumps the scooped air out in a direction opposite to disk rotation. In one embodiment, the scoop and pump channels are disposed on upper and lower surfaces of the ring and a flow through channel disposed on the inner surface of the ring connects the two.

Abstract: A read/write head for use in a disk drive and including a head body having a vertically extending core slot that extends longitudinally from a front surface of the head body in near proximity to one side thereof. A side winding slot extends horizontally from the same side to the front surface of the head body at a predetermined angle. A ferrite core member is disposed within the core slot to support a core winding in the side winding slot.

Abstract: A head/arm lock mechanism includes a pawl mounted to the armature of a bistable solenoid, the armature being stable in either of two rotary positions. The armature and pawl are limited to move through an angle less than that defined by the stable positions of the armature, so that the armature is biased by the magnetic circuit of the solenoid to one or the other limit positions. When the head/arm is in position to be locked, the solenoid is energized to lock against a spacer on the head/arm and the magnetic circuit continues to hold the pawl in a lock-engaging position upon de-energization of the solenoid. When the head/arm is to be unlocked, the solenoid is again energized to unlock the pawl from the spacer and the magnetic circuit continues to hold the pawl in an unlock position upon de-energization of the solenoid.

Abstract: A lapping plate is selectively textured for improved useful life and greater abrading consistency. Glass beads are serially propelled onto a lapping surface of the lapping plate in order to form spherical cavities of generally uniform size and distribution, and of a desired density. The cavities provide discontinuity in the lapping surface which substantially prevents workpiece hydroplaning. The cavities also receive loose abrading grit, workpiece fragments and other contaminants, resulting in more smoothly machined workpiece surfaces. Use of the lap plate with cavities also has been found to improve the co-planarity of composite magnetic transducing heads.

Abstract: A flexure for a rotary actuated load arm for use in a data storage system is disclosed. The flexure attaches a slider to the load arm. The slider carries a transducer over a track on a disk. The disclosed flexure has a high enough radial stiffness to prevent the slider from sliding and sticking in a position where the transducer cannot read or write data on the desired track.

Abstract: A 1,7 decoder is repeatedly initialized during reading of the synchrofield of the record. The decoder includes an oscillator responsive to the record to produce a binary read signal having a frequency f. A first divider produces a source data clock signal having a frequency 2/3 f. A second divider produces a data partition clock signal having a frequency 1/3 f. A phase synchronizer is responsive to the data partition clock signal to synchronize the source data clock signal. An initializer is responsive to the read signal recovered from the preamble of the record to synchronize the data partition clock signal.

Abstract: A 3/2 frequency divider employs two D-type flip-flops, an OR gate and an AND gate arranged to respond to an input signal at a frequency f to derive an output signal at a frequency 2/3 f. The frequency divider is employed in a code converter to encode or decode 1, 7, 2, 3 codes.

Abstract: An etching and fluorinating treatment is disclosed for modifying the surface properties of magnetic data storage media and sliders for magnetic data transducing heads. Media enclosed within a plasma chamber is first exposed to an argon plasma for cleaning, then exposed to a plasma mixture including argon with either fluorine or carbon tetrafluoride, maintained at a pressure of approximately half of atmospheric pressure, at a temperature of about 100.degree. C. An electrical field is generated for forming argon, carbon and fluorine ions. The argon ions etch the carbon overcoat of the disc, while the carbon and fluorine ions combine with the carbon to form extended chain fluoropolymers, and also penetrate the carbon layer. Sliders are treated in a plasma mixture of argon and CF.sub.4. During such treatment, carbon and fluorine ions penetrate exposed surface areas of the slider, and form a reaction product of solid lubricant film.

Abstract: Servo data, including three types of servo patterns distinguishable by phase, are stored in concentric servo tracks on a magnetic information storage disk. Each servo track includes a plurality of only one type of pattern, with consecutive tracks arranged in a repeating sequence of the three servo pattern types. For phase recognition, the pattern types further are arranged in a repeating sequence of angular sectors, each sector having a plurality of but one type of pattern. The servo patterns in a given storage track thus are always angularly offset from the servo patterns in the next adjacent tracks. This permits the use of servo patterns having a radial dimension greater than the separation between adjacent tracks, increasing servo signal reliability and transducer dynamic range.