Abstract: Disclosure is made of an improved aqueous magnetic coating composition employing a polyacrylic latex polymer as a dispersant. As preferred embodiments, the composition further comprises a polymeric binder having both hard and soft components, as well as the inclusion of flow agents, antifoaming agents, wetting agents and lubricants.

Abstract: The absolute value circuit of the invention comprises differential voltage to current converter means for converting an input voltage of alternating polarity into a pair of currents whose difference represents the input voltage, first and second inverter means for separately inverting each of the two currents, means for connecting the output of each inverter to the input of the other, the inverters being of the type which will only invert current of a predetermined polarity, and current summer and clamp means which are supplied with the outputs of the inverters for generating a unipolar output current signal whose magnitude represents the difference of absolute values of the pair of currents.

Abstract: A method for fabricating a metallic pattern on a substrate is disclosed. The method consists of depositing an adhesive and/or plating base material on a substrate upon which a narrow self-supporting border of photoresist is applied. An anodic layer is then deposited and the photoresist removed. The adhesive and plating base material is etched in those areas previously covered by the photoresist and fresh photoresist applied to encapsulate those areas of the anodic layer which form the final pattern of interest. The unwanted anodic material is then etched and the photoresist removed.

Abstract: An apparatus for decoding binary data from one form to another has a register adapted to receive the input bit signals. A plurality of data paths are connected to the register, with a delay means in at least one of the paths. Decoding means is adapted to generate output bit signals in response to the input bit signals. Logic means determines the correct phase relationship between the input bit signals and the output bit signals. Switching means, responsive to the logic means, selects the data path from the register to produce the correct phase relationship between the input bit signals and the output bit signals.

Abstract: A method is disclosed for precisely aligning the pole tips of a thin film magnetic head. Two separate metallic layers, such as Permalloy (Ni-Fe alloy) are separated by a layer of insulating material such as silicon dioxide or AL.sub.2 O.sub.3 which will serve as the insulative spacer of the final magnetic head. A photo-resist is applied to the surface of the top metallic layer in an imagewise configuration to establish the shape of the top pole. The top pole is then etched and the photo-resist removed. The top electrode is then encapsulated with a protective metal and is used as a mask during the chemical etching of the insulative layer, the bottom electrode being used as an etch stop. This integral structure is then used as a mask during the chemical etching of the bottom electrode, resulting in pole tips which are precisely aligned.

Abstract: In a magnetic recording disc cartridge having a recording disc contained within an upper housing and a separably mating lower housing, an improved latch and handle assembly includes a lift assembly means attached to a handle assembly which is pivotally mounted to the upper housing. The handle assembly has a cavity, a pair of spring bias means within the cavity, and an urging means adapted to urge against the spring bias means in a direction substantially perpendicular to the pivot axis and to retain the spring bias means in the cavity. The spring bias means are adapted to move from a first position wherein the handle assembly is adapted to receive the lift assembly means, to a second position wherein the spring bias means is adapted to capture the lift assembly means.

Abstract: A magnetic coating composition is disclosed of the type having magnetic particles dispersed in a resin binder. The improvement comprises the use of a solvent system including a dibasic ester wherein the solvent system has an initial Hansen three-dimensional solubility parameter range of approximately 10.5 to 11.0 and a Hansen three-dimensional solubility parameter range of approximately 9.3 to 10.0 after approximately 99% of the solvent has been evaporated from the binder.

Abstract: A magnetic recording medium and method of producing the same are taught. The medium comprises magnetic particles and alumina particles dispersed in a binder as a unitary coating whereby each of the alumina particles disposed in the binder is substantially equal to the thickness of the medium wherein the alumina particles are produced by first forming an aluminum hydrate from alumina hydrate gel according to the following equation:Al.sub.2 O.sub.3.nH.sub.2 O.fwdarw.Al.sub.2 O.sub.3.3H.sub.2 O+(n-3)H.sub.2 Oand heating the aluminum hydrate above approximately 800.degree. C. to form alumina of substantially spherical configuration according to the following equation:Al.sub.2 O.sub.3.3H.sub.2 O.fwdarw.Al.sub.2 O.sub.3 +3H.sub.

Abstract: The subject invention relates to the fabrication of metal oxide patterns on a substrate adapted for use with thin film magnetic heads. The metal oxide pattern has a precisely defined geometry including nearly vertical side walls, for minimizing read/write errors. In addition, a filler material formed from a non-magnetic, non-metallic compound is provided on the substrate in a pattern complimentary to the metal oxide pattern. In accordance with the subject invention, the top surface of the metal oxide pattern and the filler material are co-planar. By this arrangement, subsequent layers may be uniformly deposited without discontinuities. The subject method includes a plurality of distinct masking and etching steps in order to achieve the desired result.

Abstract: An access control system for controlling the velocity of a head assembly in a disc drive has a digital difference counter, to note the number of tracks to be traversed, a ROM to output two values of velocity: One value corresponding to the present remaining number of tracks and another value corresponding to the remaining number of tracks minus one. An intergrator generates a signal between each track crossing. An oscillator produces a plurality of signals per track. The signals from the oscillator are compared to the signal from the integrator by a comparator. The output of the comparator is a series of pulses, all of which have the same frequency, but with different duty cycles. This series of pulses is used by the ROM to modulate its output such that one value of velocity is outputted when the pulse is "high" and another value of velocity is outputted when the pulse is "low". The signal from the ROM is converted to an analogue signal and is used to control the head assembly.

Abstract: A servo system in a disc drive for accessing and maintaining selected data tracks on a stack of discs has a first continuous position signal derived from a pre-recorded surface and a second position signal derived from servo information in sectors of the other discs. The first and second position signals are combined to form a hybrid signal to control the actuators. The hybrid signal is the second signal when the second signal is generated. When the second signal is not generated, the hybrid signal is a modified first signal plus the last known second signal. The modified first signal is the difference between the first signal presently generated and the first signal generated when the second signal was last generated.

Abstract: Direct current null in the reproduction of a high density, digital, magnetic recording is equalized by the apparatus which first slims the magnetic head output pulse until one-half the main lobe time width of the pulse is equal to one-half the minimum time between polarity transitions, then, integrates the slimmed pulse, centers it about a zero reference voltage level, and finally, through a limiter, produces an output pulse signal which has abrupt output transitions whenever the centered, integrated pulse crosses the zero reference voltage level.

Abstract: The invention described herein is a storage container adapted to hold a plurality of substantially planar flexible members, such as flexible magnetic discs. The container has a base section and a pouch section. The pouch section is adapted to be fitted into the base section in a closed position and the pouch section is adapted to rotate about an axis such that in an open position the pouch section rests against the base section. The pouch section further has a partial front wall which is adapted to pivot about an axis enlarging the pouch section greatly facilitating the insertion and removal of the flexible planar member. Finally, the storage container has detent means to provide positive closure in the closed position.

Abstract: A method of fabricating variable sloped, as well as straight, edges on a permalloy body of a thin film head is disclosed. The process comprises forming a titanium layer on the permalloy body covering at least those areas of the body which are intended to exhibit the variable slope. A photoresist layer is formed atop the titanium layer and the permalloy body and is removed in those areas of the titanium layer and permalloy body which are not to be retained as part of the thin film head after etching. The body is then etched with an etchant containing HF and FeCl.sub.3 to form variable sloped edges in those areas of the permalloy body covered with titanium and photoresist and straight edges in those areas of the permalloy body covered only with photoresist.

Abstract: A method of manufacturing thin-film magnetic transducers in which the transducers are deposited onto a substrate member adjacent a finished and lapped surface in a manner such that no further lapping of the slider rail adjacent the transducer is required during manufacture. The method includes forming recesses on the substrate member to define slider rails and then forming air bearing surfaces on each such rail.

Abstract: An improved magnetic tape reel for computers is taught which comprises a central part carrying a driving hub having a first set of spokes extending radially outward from the outer surface of the hub and a support ring concentric with the hub and having a second set of spokes extending radially inwardly from the inner surface of the ring. Two side flanges are ultrasonically welded to the central part along the spokes forming a box-like structure having a high resistance to compression produced by tape being wound thereon.

Abstract: A magnetic head/slider assembly for flying a magnetic head on a fluid bearing relative to magnetic recording media moving in a predetermined direction, as a fluid bearing surface which is convexly curved longitudinally of the assembly. A magnetic recording head extends rearwardly of the slider body with at least a portion of its bottom surface also being convexly curved. The head/slider assembly is supported such that the portion of the assembly closest to the magnetic recording media when the media is stopped is a portion of the slider body forward of the trailing edge thereof, whereby the magnetic head gap remains spaced above the media when the media contacting portion of the assembly is resting thereupon.

Abstract: Apparatus is disclosed for recording magnetic impulses on a selectively magnetizable medium with such impulses being recorded with their axes of magnetization substantially perpendicular to the surface of the medium utilizing a recording medium having a high magnetic permeability backing layer and an overlying coating of magnetic material having uniaxial anisotropy substantially perpendicular to the surface of the backing layer, and using a unitary magnetic head for both recording and playback with such head positioned adjacent to one side of the recording medium.

Abstract: A structure and method for manufacturing said structure are disclosed for producing a surface of improved smoothness. The result is achieved by applying to the substrate a layer of low melting point metal or low melting point glass and elevating the composite structure to the melting point of said low melting point metal or low melting point glass. The said metal or glass thereupon spreads to a smooth surface of greatly improved roughness.

Abstract: A process is disclosed wherein read/write transducers are applied simultaneously to a mass of motion-constrained, pre-machined, air bearing sliders.