Abstract: An apparatus and method for positioning a transducer over the center of a track is disclosed. An arm carries the transducer. Embedded in the arm is a heating element. The heating element is positioned so that the linear expansion or contraction of the arm resulting from the temperature rise or drop due to the amount of heat applied to the arm by the heating element will move the transducer across the track. In operation, a constant amount of heat is initially applied to the arm to center the transducer. During tracking, a circuit varies the amount of power applied to the heating element so that the transducer is kept over the center of the track.

Abstract: Run length limited codes, such as (1,7) codes are recovered with a dual channel recovery system in which the high resolution channel normally supplies the output (recovered) signal. The low resolution channel includes a detector, such as a delay device and gate, to detect a predetermined absence of transitions in the low resolution signal (which is indicative of long strings of successive zeros) to inhibit the high resolution channel from supplying the output. The result is to effectively block the high resolution channel from providing a false output.

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.

Abstract: An improved method for controlling magnetic quality of electroless plating in which the plated substrates are subjected to magnetic film deposition for a true plating time determined by offsetting the total plating time by the activation time, the activation time being the time for surface potential transients to decrease and steady state surface potential to occur.

Abstract: A double density plug and socket electrical connector employing the same form factor as existing 50 pin subminiature "D" connectors. Adapted for use on printed circuit boards the connector can compatibly interconnect 50 pin or 100 pin electrical connectors. The double fifty plug-socket connector can carry a multiple byte wide SCSI bus.

Abstract: A magnetoresistive head having separate write and read gaps including a leading write pole, a trailing write/shield pole, and a following shield pole, wherein an elongated magnetoresistive sensor strip having a central sense region is mounted in the read gap, and further wherein the leading write pole has a length corresponding to the central sense region of the sensor and defines a track width, and the trailing/shield pole and following shield are the same length as the overall length of the magnetoresistive sensor strip.

Abstract: A self-loading negative pressure air bearing slider is formed having side vents. The side vents allow for repeatable manufacturing of the basic slider in fewer steps while retaining the desirable features of high stiffness and substantially constant flying height found in negative pressure air bearing sliders.

Abstract: A retriggerable monostable multivibrator according to the present invention comprises a bistable device, such as S-R latch, responsive to the output of a pulse former to provide a set output. A propagation chain, comprising a plurality of serially arranged gates, propagates the latch output to form a delayed reset signal. The reset signal operates to reset the bistable latch. Gate means is connected to the true output of the latch, and to the propagation chain, to provide an output pulse for the duration of the true output and reset signal. The gates of the propagation chain are also connected to the pulse former so that the propagation of the reset signal is terminated in the event a second input pulse occurs prior to termination of the reset signal.

Abstract: A thin film magnetic data transducer carried on the end of a conductive flyer has its magnetic pole electrically connected to the flyer to prevent electrostatic discharges between the flyer and the pole tip from eroding the pole tip. The winding of the transducer is also electrically connected to the flyer either through a high resistance, through a diode with high forward and reverse voltage drops, or through a fusible link, so as to bleed off static charges on the winding without their arcing through to the magnetic pole and damaging the insulation between the winding and the magnetic pole. These embodiments avoid any degrading of the data readback signal.

Abstract: A method and apparatus for increasing the amount of data capable of being stored in a magnetic storage device is disclosed. Basically, a magnetic characteristic of the disk to head interface is measured at several locations on the disk. The frequency for writing and reading the data is optimized in terms of the required resolution and the magnetic measurement. The read and write modes are then varied, based upon the optimized frequency, such that data is written on the disk at a frequency substantially equal to the optimized frequency and read from a disk having data recorded at the optimized frequency.

Abstract: A read write head for magnetic recording on a magnetic media includes a core having a gap with confronting surfaces. To increase the magnetic saturation properties of the head, one of the confronting surfaces is covered with a layer of material having a higher magnetic permeability than the material making up the core. An additional surface of the core is also covered with the higher magnetic permeability material to prevent the flux lines from fringing into the atmosphere at the joint. The two layers of material form an integral layer of the second higher permeability magnetic material.

Abstract: An enclosed slurry dispensing system employs a sealed pressurized reservoir for supplying slurry through a bypass chamber to a dispensing nozzle. Excess slurry is bypassed through the bypass chamber to an intermediate chamber. Slurry is allowed to return to the reservoir through a normally-closed check valve, closed by the higher pressure of the reservoir. The system is purged by opening the reservoir to the atmosphere, creating a sub-atmospheric pressure in the bypass chamber. Air is admitted through the nozzle to purge the nozzle of slurry. At the same time, the check valve opens and excess slurry returns to the reservoir from the intermediate chamber.

Abstract: A method and apparatus for placing a ferrite core in the slot of a pad of a ferrite head. A circular magnet is mounted below a non magnetic table on a slider slidable along a line. The pad is clamped on the table with its slot exposed and aligned along the line and the center of the magnet. When the ferrite core is placed on the table near the magnet, it stands on edge, aligned along a radial line of flux from the magnet. As the magnet is slid towards the slot, the core follows the center of the magnet, aligned along the centerline of the slot following the radial line of flux. The core slides into the slot and is thereafter bonded to the pad.

Abstract: Apparatus is shown for mixing and dispensing an epoxy adhesive. An epoxy resin and its associated curing agent are simultaneously loaded from separate cartridges into a length of flexible PVC tubing, part of which is contained between a rotor and a stator. Bearings, mounted rotatably about the rotor, engage and travel along the tubing as the rotor is revolved, each bearing compressing the tubing at its point of engagement. The tubing, repeatedly compressed and released by each bearing in succession, kneads the epoxy resin and curing agent into a homogeneous mixture. From the tubing, the epoxy mixture is deposited on a moving carrier tape and forms a continuous bead. Downstream, a control tape is spaced apart from the carrier tape and moves in the opposite direction. As the bead encounters the control tape, the control tape removes part of the bead material from the carrier tape and plastically forms the remaining mixture into a film of a uniform thickness substantially less than the bead diameter.

Abstract: An apparatus for testing the surface properties of a material is disclosed. The apparatus includes an indentor which is suspended above the surface of a sample and dropped onto the sample. Several testing methods are also disclosed. Surface toughness is measured by dropping the indentor from a variable height and inspecting the surface for failure. Thin film strength is tested by making several drops from various heights and inspecting the surface for flaking of the layer. In addition, damping capacity can be measured by comparing the kinetic energy of the resulting from the drop of the indentor to the strain energy measured by a probe on the opposing surface of the sample.

Abstract: A data storage system has a plurality of individual data storage units, each of which can undergo unpredictable independent failure. By dividing data blocks to be stored therein into a number of sub-blocks one or more less than the number of data storage units and creating a redundant data sub-block of the type permitting reconstruction of any one sub-block of data using the remaining sub-blocks and the redundent sub-blocks, and then storing each of the data sub-blocks and the redundant sub-block on a different one of the data storage units, it is possible to reconstruct any one failed data sub-block of a related group using the other sub-blocks. It is necessary to be able to detect the failure of the sub-block, and the preferred way is by a multibit error detection code appended to each sub-block, or by failure sensed within and by an individual data storage unit.

Abstract: An improved self-loading magnetic head slider for recording and reading data on a magnetic storage disk, is characterized by the addition of aerodynamically designed wings used for lowering the slider close to the surface of the disk to a designed head-to-disk separation as the disk is rotated. The magnetic head slider does not contact the magnetic storage disk surface.

Abstract: Provided is a circuit for removing an unwanted temporal portion of an incoming signal and for differentiating that signal with respect to a reference voltage level. It includes an input for receiving the incoming signal current through an input capacitor, a differential amplifier for converting input charging current into a voltage with respect to a reference voltage, and a charging capacitor for holding a voltage level representative of the charging current supplied to the differential amplifier during times when the unwanted input signal portion is to be removed from the circuit's output. A current sink and source provides a reset period voltage charge to the input capacitor during times when the unwanted portion is to be removed from the outgoing signal. A switch responds to a reset signal immediately preceding or on the occurrence of the unwanted signal portion.

Abstract: A dual channel readback recovery circuit includes a high resolution channel and a low resolution channel and a data latch. A logical filter in one or both channels rejects signals that are followed by other signals if they are spaced apart less than the rejection time interval allowed by the code used. Polarity qualifying logic rejects signals in the channel that are not matched in polarity.

Abstract: Ferromagnetic cobalt-iron (CoFe) is electrodeposited on a conductive substrate to form a CoFe thin film. The wet electrodeposition process disclosed involves use of a relatively low toxic plating bath solution in which the constituents cobalt and iron are introduced as soluble salts. A lesser amount of iron than cobalt is used to develop an approximately 90% cobalt to 10% iron ratio in the thin film. The plating solution also has sodium saccharin, dodecyl sodium sulfate and wetting and buffering agents. The CoFe thin film that results from using the disclosed process has near zero magnetostriction, acceptable permeability for use as a magnetic head, a highly stabilized magnetic domain and approximately twice the saturation moment of Permalloy. Magnetic heads fabricated from such film are well suited for use with high coercivity media for high density recording.