Abstract: A film transducer head design is formed on a substrate where the first yoke layer and electric terminal strip that connects the coil center pad to the head exterior are formed at the same time followed by successive layers that form the transducer gap, coil insulation, coil, coil insulation and the second yoke layer. This sequence allows the coil to be tested immediately after deposition of the coil material and at a time in the fabrication sequence when it can be reworked or replaced if a discontinuity (open) or shorted turn(s) is (are) identified.

Abstract: A film type magnetic transducer head has a yoke formed partially of high permeability material which provides enhanced read capabilities and partially of high saturation magnetization material to obtain the write function benefits associated therewith. The high saturation magnetization material is used in the pole tip region and extends to a location beyond the point of initial saturation and does not extend to a position at which the first coil winding is embraced to prevent or minimize coupling with the windings. With the balance of the joke of high permeability material, the transducer functions substantially as a wholly high saturation magnetization yoke in the write function and as a wholly high permeability material yoke for read purposes.

Abstract: A rigid magnetic disk substrate is spin coated using a closely confining, stationary air barrier adjacent the surface being coated. The coating is applied through a slotted opening in the air barrier which is progressively closed as the coating is applied and completely sealed during the spin-off operation. During the application of the coating, the air barrier is positioned approximately 0.15 inch from the disk substrate surface and prior to spin-off, the barrier is moved to a position 0.025 inch from the coated surface. Further, during the high speed spin-off cycle a high kinematic viscosity gas, such as helium, is introduced into the space between the barrier and the coated surface to establish a laminar flow condition and eliminate spoking of the coated material.

Abstract: The composition and method of making a magnetic recording media using a polyurethane binder system with high lubricant retention and a high concentration of magnetic particles is described. The use of hydrated alumina with a solvent blocked isocyanate is used to produce an open cell microporosity in the cured coating wherein the individual voids are not greater than the magnetic bit cell size and the alumina particles remain in the coating to improve abrasion resistance. The porosity size is controlled by a surface active agent additive. Also shown is the method of preparing hydrated alumina with small particle size, dispersibility, and compatibility, and wherein the dehydrating temperature has the same range as the isocyanate deblocking temperature whereby the CO.sub.2 formation that creates the porosity occurs as the polyurethane components cure.

Abstract: A semi self-loading air bearing ferrite slider assembly has a tapered leading surface portion extending from a cross rail from which side rails and a middle rail extend rearwardly. The middle rail progressively narrows to form the transducer portion where it extends across the gap between the body portion and core piece near the trailing end of the rail. Etched surfaces between the middle rail and the side rails provides subambient pressure during operation when the slider is in flight whereby the balance between the repelling air bearing surface and attraction of the subambient pressure areas supplements the stabilizing force of the load arm.

Abstract: In parallel track data storage systems, such as disk files, servo information is recorded using a plurality of constant frequency fields each having a phase shift between tracks. Servo information is thus encoded in the phase of the servo pattern instead of the amplitude of the servo signal lobes. Multiple phase shifts per track are used to make the signal constantly varying with transducer head displacement. Phase is measured modulo 360.degree. such that the phase of a given field will go through 360.degree. every M tracks. By using several fields having different values of M, coarse, medium and fine position resolution can be obtained with the same servo pattern and demodulation scheme. Further, using two fields, one field may be split and positioned at either side of the other field to provide a common center for both fields and eliminate error conditions due to factors such as speed variation.

Abstract: A sector servo seek control samples each sector to obtain sector time, the track identification within a sequence of track types and a position error signal for a track location to track location seek. The device during each sector determines the actual transducer track location and the next sector projected track location with respect to the sequence of track types. The projected track location is corrected using the error signal to find the actual location, but if a sector signal is missing or erroneous, the projected location is used as the actual location, permitting a composite correction to be made when a correct sector signal is obtained. The seek time is minimized by using maximum acceleration followed by maximum deceleration while not exceeding a velocity value that would cause the device to overshoot the target track using full deceleration.

Abstract: A magnetic recording coating has a high density of magnetic particles uniformly dispersed in a thermoset resin binder with the dispersion applied as a thin coating onto a rigid substrate. The thermoset resin binder comprises a phenolic, an epoxy, and a styrene allylalcohol. The curing action of this coating is initiated by blocked acid catalysts. The material can be cured at a low temperature to produce a smooth, hard coating with an improved orientation ratio and without impairing the properties of the magnetic particles.

Abstract: The data recovery procedure for errors caused by track occlusion as a result of adjacent track misregistration or head sensitivity to the low frequency content of adjacent tracks is effected by reading and storing the information from the adjacent tracks and thereafter erasing the adjacent tracks either on centerline or with the transducer offset toward the intermediate track of interest. The track of interest can then be read with the transducer aligned with the track centerline and at varying positions of offset. If this sequence of rereads fails, the erase step can be repeated with greater amounts of offset toward the intermediate track to further reduce inband interference and the reread sequence also repeated.

Abstract: A multiple transducer disk file format and head addressing/switching control circuitry is shown and described which permits reading all sector identifier (ID) fields during a single rotation of the media using uniformly staggered sectors. This results in an average access latency of one-half revolution of the media and enables the use of maximum or selectively reduced data rates secured by successively storing data in sectors separated by sector fractions which are multiples of the uniform staggering between sectors within a cylinder.

Abstract: A sector servo seek control samples each sector to obtain sector time, the track identification within a sequence of track types and a position error signal for a track location to track location seek. The device during each sector determines the actual transducer track location and the next sector projected track location with respect to the sequence of track types. The projected track location is corrected using the error signal to find the actual location, but if a sector signal is missing or erroneous, the projected location is used as the actual location, permitting a composite correction to be made when a correct sector signal is obtained. The seek time is minimized by using maximum acceleration followed by maximum deceleration while not exceeding a velocity value that would cause the device to overshoot the target track using full deceleration.

Abstract: A three level motor speed control for a device such as a magnetic disk drive requiring a closely regulated running speed provides for acceleration, deceleration, obtaining close speed regulation and maintaining speed regulation of a rotating device during operation. The first level control provides acceleration or deceleration while checking velocity each eighth revolution and the second level control uses single revolutions to measure speed over an accurate rotational distance to obtain close speed regulation. Both level one and level two are controlled by the device controller. During run conditions with no error signal, a third level of control of the closely regulated velocity is maintained by separate hardware circuits which frees the processor for other uses. An error condition forces control to level one for re-establishment of the regulated running speed and a command to stop the drive forces control to level one for deceleration and stop procedures.

Abstract: A transducer-carriage assembly is shown which includes an intermediate adapter that enables the subassembly to be fabricated in a manner that eliminates the effect of tolerances in the component parts, prior to incorporation into the final assembly, with respect to penetration, pitch and roll of the transducer.

Abstract: Shown and described is a recirculating air system for a disk drive assembly wherein air moves radially over the disk surfaces, over the transducer carriage at an increased velocity, past the actuator mechanism and through a filter before recirculation is induced by the hub assembly on which the disks are mounted and which functions also as an impeller. The hub-disk assembly also forms an integral part of the drive motor rotor assembly. Also, a breather filter and breather opening communicate with the recirculating air path at the low pressure location of the recirculating path to assure that air entering the system passes through the breather filter.

Abstract: The disclosure is directed to a method and apparatus for superfinishing magnetic disk substrates using a non-friable polishing pad including a high density polyurethane foam binder in which at least 50 per cent by weight of classified hard particles are retained. Polishing occurs by rotating the pad against the surface to be ultrafinished in the presence of a water soluable liquid vehicle maintaining a minimum pressure of 5 pounds per square inch at a rotational speed that achieves the desired aggressiveness of the polishing media. The method and apparatus contemplate both the ultrafinishing of newly prepared substrate disks and the restoring of previously coated disks to a ultrafinished substrate condition without producing substances or conditions toxic to the ecology or the operator.

Abstract: The grinding media is formed of a concentration of agglomerate free hard particles exceeding 50 percent by weight of the media, wherein the particles are chelated by a dispersing agent, surface treated with a surfactant, mixed with polyether polyol and polyisocyanate plus a catalyst and water and thereafter rapidly cured in a closed mold which has been preheated to a temperature exceeding 50.degree. C. and a pressure of 60 to 120 PSIG. The water reacts during curing to create a polyurea linkage and release CO.sub.2 as a blowing agent. The resulting media has a low elastic modulus with particles retained in a polyurethane-urea binder system. The media composition may also include an inorganic filler such as glass fibers not exceeding 30 percent by weight of the media.

Abstract: A servo writing transducer is shown having transverse side surfaces of the pole pieces adjoining the gap formed to optimize compression of the fringe field at one transverse side to reduce the dead band intermediate servo tracks. The existence of a wider fringe field region at the opposite transverse side is without consequence since the servo writing procedure is to first write the farthest track at the transducer side at which the compressed field occurs followed by each succeeding, adjoining servo track causing the information written in the wide fringe field to be overwritten by the next track.

Abstract: A magnetic transducer support assembly includes parrallel flexure spring supporting elements which are of sufficient length to approximate linear motion over the length of translational displacement used. The flexures are formed of a single continuous length of flat spring material, and built-up portions on the spring stretches between the base member and transducer carriage are provided to resist twisting and other unwanted motions induced by vibration and similar influences. Displacement is achieved by cam actuation driven by a stepper motor which may control multiple such transducer mountings on a single side of a disk or on opposite sides of a disk.

Abstract: The magnetic head actuator includes a substantially totally enclosed self-shielding voice coil linear motor which includes a continuous, cylindrical permanent magnet of flexible material which is sealed against the inner cylindrical wall of the outer core by a flared copper sleeve that also serves as a non-magnetic, conductive shorted turn to reduce instantaneous inductance of the drive coil. An annular reluctance gap in the outer core provides symmetrical distribution of the permanent magnet flux.

Abstract: The burnishing tool has a plurality of holes in the planar surface which engages the flexible magnetic disk. Each hole contains a burnishing blade positioned at 45.degree. to the direction of motion. A manifold connects each hole to a vacuum pump which draws air into the holes causing the flexible magnetic disk to fly against the planar surface. The vacuum also removes the debris from the burnishing tool.