Abstract: A magnetoresistive (MR) read transducer comprising an MR layer having passive end regions separated by a central active region. A longitudinal bias is produced by a thin film of hard magnetic material in the end regions only, and the thin film of hard magnetic material is spaced from the MR layer by a nonmagnetic spacer layer so that a magnetostatic longitudinal bias is produced of a level to maintain the passive end regions of the MR layer in a stable state.

Abstract: An air bearing slider for supporting a transducer is provided with a pair of rails having an air bearing surface with a continuously curved part with its greatest width at the leading end of the slider. In the rear area of the slider the air bearing surfaces are of equal width. The invention furthermore provides a mechanical grinding process using a grinding wheel having two grinding disks separated by a spacer disk and provided with bevelled grinding surfaces on its inner sides. Either by advancing the turning grinding wheel parallel to the surface of the slider from the trailing towards the leading end up to a certain point or in accordance with another embodiment by tilting the slider slightly towards the advance motion and continuously advancing the grinding wheel, the continuously curved air bearing surface portions are provided in a simple and efficient manner.

Abstract: A printer suitable for color printing which uses an ink jet printhead in which the marking fluid contains no dye so that a latent image of the desired print pattern is produced in the form of moistened spots directly on the print medium. The latent image is then developed by applying some colored powder to the print medium, and the developed image is then fixed to the print medium to produce a visible image of the desired print pattern.

Abstract: A magnetoresistive (MR) read transducer comprising a thin film MR layer formed of ferromagnetic material and a nonmagnetic thin film spacer layer in contact with the MR layer. The spacer layer comprises a material selected from the group consisting of nichrome and nichrome with chromium oxide. A thin film of soft magnetic material is deposited in contact with the spacer layer so that a transverse bias is produced in at least a part of the MR layer. A feature of the invention is that the resistivity of the spacer layer can be chosen by selecting the ratio of nichrome to chromium oxide in the spacer layer. In a specific embodiment the spacer layer extends over only the central region of the MR layer. In case the MR layer is a nickel based alloy, a wet chemical etching process using an etchant comprising an aqueous solution of ceric ammonium nitrate and acetic acid can be used to pattern the spacer layer.

Abstract: A process for the batch fabrication of an array of shielded magnetoresistive (MR) read transducers comprising the steps of depositing a full film over the entire substrate of a first magnetic shield layer, a first non-magnetic gap layer and sputter depositing a layer of MR sensor material in the presence of a magnetic field for orienting the anisotropy axes of the layers of MR sensor material in a chosen direction. The MR sensor layer and the first gap layer are permitted to produce a plurality of MR read transducers, and the first magnetic shield layer is then patterned to produce a first shield for each of the MR read transducers. A second gap layer and a second shield layer are patterned to produce a second shield for each of the MR read transducers.

Abstract: The method for making a shielded magnetoresistive (MR) sensor in which the first shield is made of sendust and the second shield is made of permalloy. The method comprises the stages of depositing a layer of sendust to form a first shield; heat treating the sendust layer at a temperature greater than 400.degree. C.; depositing a first electrically insulating layer; depositing, in the presence of a magnetic field, a MR layer; depositing a second layer of electrically insulating material; and, depositing a layer of permalloy to form the second shield.

Abstract: A lapping control system for a row of thin film magnetic transducers formed on a substrate. Each of the magnetic transducers comprises a magnetoresistive (MR) element, and the row is supported on a holder which has an elongated H-shaped slot near one edge to form a beam member upon which the row is mounted. The beam member is capable of being deflected in a substantially quadratic curvature when subjected to pressure from a pressure transducer at the middle of the beam member. The resistance of each of the MR elements is measured during lapping, and a control signal is generated to control the pressure transducers to control lapping with proper BALANCE and BOW and to terminate lapping when the desired MR element height is reached.

Abstract: A lapping control system for a row of thin film magnetic transducers formed on a substrate. Each of the rows comprises a plurality of thin film magnetic transducers and at least two test structures. Each test structure has at least two elements which comprises some combination of switch elements or test thin film magnetic transducers. As the row of transducers is lapped, each time one of the switch elements is opened, the saturation current (ISAT) of one or more of the thin film magnetic transducers is measured and recorded so that a correlation between ISAT and throat height of the transducers is established during lapping. This correlation is used to establish the point at which lapping should be terminated.

Abstract: An air bearing slider for supporting a magnetic transducer comprising a pair of coplanar side rails on the sides of an air bearing surface of the slider and a center rail along the central region of the air bearing surface to form recessed areas between the rails which extend from the leading to the trailing end of the slider. All the rails have a tapered section at their leading ends. The side rails have a width that does not exceed the width of the side rails at the leading end, and the side rails extend only part way to the trailing end of the slider. The width of the center rail is small at the leading end and greatest at the trailing end of the slider, where the transducer is supported.

Abstract: A protective circuit for a magnetoresistive (MR) element having a first and a second terminal in which a first current source is coupled to the first terminal of the MR element to produce a bias current through the MR element and a second current source is coupled to the second terminal of the MR element to produce a reference current. Circuit means coupled across the MR element senses the center potential of the MR element substantially midway between the first and second terminals, and a feedback circuit responsive to the sensed center potential is coupled to adjust the current output of the first current source to maintain the center potential to a selected reference voltage to protect the MR element from short circuits to a conductive area of the magnetic recording medium.

Abstract: A magnetoresistive (MR) read transducer comprising a thin film MR layer formed of ferromagnetic material and a nonmagnetic thin film spacer layer in contact with the MR layer. The spacer layer comprises a material selected from the group consisting of nichrome and nichrome with chromium oxide. A thin film of soft magnetic material is deposited in contact with the spacer layer so that a transverse bias is produced in at least a part of the MR layer. A feature of the invention is that the resistivity of the spacer layer can be chosen by selected the ration of nichrome to chromium oxide in the spacer layer. In a specific embodiment the spacer layer extends over only the central region of the MR layer. In case the MR layer is a nickel based alloy, a wet chemical etching process using an etchant comprising an aqueous solution of ceric ammonium nitrate and acetic acid can be used pattern the spacer layer.

Abstract: A method for making a thin film magnetic head in which the pole tips are trimmed to a predetermined width prior to the completion of the magnetic yoke structure. The thin film magnetic head is produced through deposition of the first magnetic layer in two stages, through deposition of the coil, the insulating material for the coil and through deposition of the second magnetic layer. The thin film head is then masked by a photoresist mask having openings to expose specific parts of the pole tip region, and an ion milling operation is used to etch the head assembly to form pole tips having a predetermined width. The shaping layer for the second magnetic layer is then deposited to complete the magnetic yoke structure.

Abstract: A magnetic recording head assembly for perpendicular magnetic recording for the type in which both the main magnetic pole and auxiliary magnetic pole are on the same side of the magnetic medium. The auxiliary magnetic pole is made from a material having the property that the permeability varies in direction of relative movement between the magnetic recording medium and the magnetic head assembly, with the permeability progressively increasing from each edge to the center of the auxiliary magnetic pole.

Abstract: A method and apparatus for detecting abnormal operation in a magnetic disk file which comprises reading data for each head and each track to obtain a readback signal. The readback signal is read from a predetermined area of each track on a disk that is not normally rewritten during normal operation of the system. The amplitude of the signal read from one track is compared with the amplitude of the signals read from other tracks, and an alarm condition when the comparison indicates a variation which exceeds a predetermined level. Corrective action can be taken in response to the alarm condition prior to an actual failure condition in the magnetic disk file.

Abstract: An array of resistive heater elements, each of which is connected in an electrical circuit between a common electrode and one of the control electrodes. Each of the resistive heater elements comprises a plurality of portions arranged so that a small elongated opening in provided at the middle of the heater element where no resistive material is present. Each of the resistive heater elements, when energized, has a bubble formed at each of the plurality of portions. All of the bubbles coalesce to form a single pillow-shaped bubble which causes a drop of ink to be ejected from the associated nozzle. During collapse of the bubble, the bubble collapses inwardly so that cavitational shock impacts the heater element at the opening and little or no damage to the resistive heater is produced.

Abstract: A thermal drop-on-demand ink jet print head in which thermal cross-talk problems are eliminated by providing heat shield members in the space between each of the heater elements. The heat shield members comprise metal fingers attached to either the common heater electrode or one of the control electrodes. The heat shield members enhance flow of heat into the substrate to thereby minimize thermal cross-talk among adjacent channels.

Abstract: A magnetoresistive (MR) sensor which is provided with longitudinal bias by means of exchange coupling between the ferromagnetic MR layer (NiFe) and an ultrathin layer of an antiferromagnetic material (FeMn) with a thickness within the range of about 25 to 200 angstroms. The exchange structure is capped by a protective film to prevent oxidation damage to the exchange structure during subsequent thermal cycling. The capping layer is a dielectric or metal oxide (cermet) film such as Cr.sub.2 O.sub.3, Al.sub.2 O.sub.3, Cr - SiO or Si O.sub.2. Alternatively, the capping layer can be a laminated FeMn-Lx film where Lx is taken from the group consisting of Cr.sub.2 O.sub.3, Al.sub.2 O.sub.3, and Si O.sub.2.

Abstract: A high speed magnetic disk recording system is described in which the recording medium comprises a substrate having a magnetic coating thereon, and a magnetic recording transducer is operated in physical contact with the recording medium. The magnetic transducer comprises a single crystal material on at least the surface which contacts the recording medium. The single crystal material has a high thermal conductivity, a low friction coefficient and a high surface energy so that, when relative motion is provided between the magnetic recording transucer and the recording medium, an attractive force is generated which maintains the magnetic recording transducer in contact with the recording medium so that high density recorded data can be reliably written and sensed without excessive wear to either the magnetic transducer or the recording medium.

Abstract: An improved magnetoresistive (MR) read transducer in which a layered structure comprising an antiferromagnetic layer in direct contact with an MR layer is subjected to a thermal annealing process by heating the structure to a temperature within a chosen range for a chosen time so that a new ternary antiferromagnetic alloy is formed by diffusion. The ternary antiferromagnetic alloy has a high value of exchange bias which is less temperature sensitive. In a specific embodiment in which the MR layer is NiFe and the antiferromagnetic layer is FeMn, the ternary alloy formed by heating the structure to a temperature within the range of 260.degree. C. to 350.degree. C. for 50 to 20 hours has a room temperature exchange bias field with NiFe of about 50 Oersted and an ordering temperature which exceeds 300.degree. C.

Abstract: A sputtering apparatus for coating a substrate comprising a first electrode for supporting a suitable target material and a second electrode for supporting a substrate, upon which a coating is deposited. A source of RF power is connected to impose an RF voltage across the electrodes to produce a glow discharge in the space between the electrodes. A shield is provided surrounding the peripheral edges and the back of the second electrode, and this shield is spaced a substantial distance from the back of the electrode. Electrical insulating material is placed in the space between the shield and the back of the second electrode with a small gap between the electrical insulating material and the shield. The configuration of the shield, the insulating material, and the second electrode eliminates spurious sputtering from the peripheral and back regions of the second electrode so that very high power levels can be achieved and sputtering can be done very efficiently at high sputtering rates.