Patents Represented by Attorney Nathan N. Kallman
  • Patent number: 5768073
    Abstract: A magnetic thin film head with reduced undershoot characteristics includes a pair of relatively high permeability pole members having a low permeability gap member therebetween. Disposed adjacent to the surfaces of the pole members, which are opposite to the gap member, are layers of magnetic material of lower permeability than the permeability of the pole members, these lower permeability layers having a Curie point temperature which is within the operating temperature range of the head so that these lower permeability layers are paramagnetic. In operation, the lower permeability layers provide a change in permeability across the head gap which reduces the transition in permeability at the head pole tips, thereby reducing undershoots.
    Type: Grant
    Filed: February 7, 1997
    Date of Patent: June 16, 1998
    Assignee: Read-Rite Corporation
    Inventors: Daniel A. Nepela, Charles R. Bond
  • Patent number: 5764451
    Abstract: A magnetic head includes an inductive coil electrically partitioned into a plurality of segments by a plurality of conductive leads. During the data reading mode, magnetic flux changes emanating from a record medium are sensed by the magnetic head. The inductive coil transduces the magnetic flux changes into electrical signals at the conductive leads. The signals are amplified by serially cascading the plurality of segments and the signals are then fed into amplifiers. During the data writing mode, the electrical signal is applied to two of the conductive leads via a data writing amplifier. The inductive coil converts the electrical signal into changes in magnetic flux for recording onto a magnetic medium.
    Type: Grant
    Filed: November 4, 1997
    Date of Patent: June 9, 1998
    Assignee: Read-Rite Corporation
    Inventor: Eric R. Katz
  • Patent number: 5758406
    Abstract: A test fixture for assembling and electrical testing of a magnetic head includes a fixed baseplate, a cage, and an X-Y positioner that is adjustably mounted on the baseplate. The cage is formed of a flat, thin, elongated arm and is secured at its rear end to the X-Y positioner. The forward end of the cage extends into a notched section that surrounds part of the slider. A stationary mounting block supports and retains the suspension in a fixed position relative to the slider. In another embodiment, the rear end of the cage is secured to the stationary mounting block and the X-Y positioner supports the suspension. The testing method includes pre-wiring a slider and separately mounting the wired slider and suspension into the test fixture. Adhesive is applied on the slider or suspension for establishing a temporary bond between the slider and the suspension. The suspension is then loaded onto and temporarily positioned relative to the slider.
    Type: Grant
    Filed: February 7, 1997
    Date of Patent: June 2, 1998
    Assignee: Read-Rite Corporation
    Inventors: Michael D. Hunsaker, Barry W. Darr
  • Patent number: 5754367
    Abstract: The air bearing surface (ABS) of an air bearing slider is formed with etched pads and a leading edge shaped shallow etch step taper region that extends continuously between first and second sides of the slider. A first pad is formed on the slider and extends from the trailing edge between the first side and a central axis and has a first extension at the step taper region. The first extension has a leading edge that is angled toward the first side of the slider. A second pad is formed on the slider and extends from the trailing edge between the second side and the central axis and has a second extension at the step taper region. The second extension has a leading edge that is angled inwardly toward the central axis. The first pad and the second pad provide an air bearing surface (ABS) for the slider. A deep central recess is bounded by the first pad, the second pad, and the step taper region.
    Type: Grant
    Filed: May 19, 1997
    Date of Patent: May 19, 1998
    Assignee: Read-Rite Corporation
    Inventors: Ciuter Chang, Pablo Gabriel Levi
  • Patent number: 5750275
    Abstract: A magnetic thin film recording head includes laminated magnetic pole members, adjacent pole members being separated from each other by nonmagnetic insulating layers to reduce eddy current effects between the laminated members. The nonmagnetic insulating layers extend from the throat region of the head toward the pole tip region and terminate at a distance from the air bearing surface which is a function of the skin depth of the magnetic pole material for the particular recording frequency range being employed in the head.
    Type: Grant
    Filed: July 12, 1996
    Date of Patent: May 12, 1998
    Assignee: Read-Rite Corporation
    Inventors: Eric R. Katz, David I. Berger
  • Patent number: 5748413
    Abstract: A magnetoresistive (MR) read transducer includes an MR sensor element having end regions and a center active region. The end regions are pinned both top and bottom by an exchange coupling antiferromagnetic material. This pinning action causes the end regions to act as permanent magnets having the same remanent magnetic moment M.sub.r as that of the center active region, thereby resulting in suppression of magnetic edge effects in the transducer. A magnetic soft bias layer adjacent to the magnetoresistive sensor element also has its ends pinned by exchange coupling antiferromagnetic material.
    Type: Grant
    Filed: June 4, 1996
    Date of Patent: May 5, 1998
    Assignee: Read-Rite Corporation
    Inventors: Marcos M. Lederman, Samuel W. Yuan
  • Patent number: 5742459
    Abstract: A magnetic head assembly includes a read head having an active central region and two inactive side regions contiguously formed relative to the central region. The central region includes a magnetoresistive (MR) transducer for enabling active sensing of data recorded on a magnetic medium. Protective layers encapsulate the central region and separate it from the side regions, such that diffusion and electromigration are reduced. Each end region includes a longitudinal bias layer, and a multilayered conductive section. The longitudinal bias layer may be formed of alternating layers of antiferromagnetic material and layers of soft magnetic material and/or hard magnetic longitudinal bias. The multilayered conductive section includes conductive leads that do not contact either the MR element or the soft bias layer.
    Type: Grant
    Filed: June 20, 1996
    Date of Patent: April 21, 1998
    Assignee: Read-Rite Corporation
    Inventors: Yong Shen, Chyu Jiuh Torng, Daniel A. Nepela
  • Patent number: 5742162
    Abstract: A magnetic sensing structure includes a spin valve sensor having a pinned magnetic layer and a free magnetic layer, the direction of magnetization of the free layer varying as a function of the magnetic field applied to the structure. A multilayered magnetic keeper structure is provided to cancel the magnetostatic field from the pinned layer to provide an ideal bias profile for the structure in the absence of an applied magnetic field. Longitudinal magnetic bias may be applied to the spin valve sensor through a contiguous junction magnetic structure adjacent to the keeper structure and spin valve sensor.
    Type: Grant
    Filed: July 17, 1996
    Date of Patent: April 21, 1998
    Assignee: Read-Rite Corporation
    Inventors: Daniel A. Nepela, Marcos M. Lederman
  • Patent number: 5739990
    Abstract: A magnetoresistive spin valve giant magnetoresistive (GMR) transducer includes a magnetoresistive (MR)/GMR multi-layer with end portions spaced by a central active portion. A pair of electrical lead layers conducts electrical bias current to the transducer. Each electrical lead layer forms abutting junctions in contact with respective end portion of the MR/GMR layers. The longitudinal bias for the MR/GMR layers is provided by a pair of magnetic bias layers. Each magnetic bias layer is disposed in contact with a respective end portion of the MR/GMR layers. Bias current flows into the MR/GMR layers directly through the abutting junctions, allowing the magnetic bias to assume a different bias path through the end portions of the MR/GMR layers. The MR/GMR transducer allows both the electrical and magnetic biases to be optimally designed, without any constraint of one restricting the other, as the two biases often pose conflicting requirements.
    Type: Grant
    Filed: November 13, 1996
    Date of Patent: April 14, 1998
    Assignee: Read-Rite Corporation
    Inventors: Durga P. Ravipati, Samuel W. Yuan
  • Patent number: 5739987
    Abstract: A read transducer assembly includes a giant magnetoresistive structure in magnetic contact with a multilayered biasing structure that includes layers of antiferromagnetic material interleaved with layers of soft magnetic material. The magnetic exchange coupling between the antiferromagnetic layers and the soft magnetic layers results in a bias field to the giant magnetoresistive structure that reduces or eliminates side reading by the read transducer assembly. The multilayered biasing structure is located adjacent to and in magnetic contact with either the end or the top surfaces of the giant magnetoresistive structure.
    Type: Grant
    Filed: June 4, 1996
    Date of Patent: April 14, 1998
    Assignee: Read-Rite Corporation
    Inventors: Samuel W. Yuan, Daniel A. Nepela, Marcos M. Lederman
  • Patent number: 5734533
    Abstract: An air bearing magnetic head is formed with a dual gap for minimizing side fringe fields, side reading, side writing, cross-talk interference, and pulse asymmetry, while maintaining the efficiency of the head. The method of manufacturing the head enables the control of the effective track width with great precision. The head is made by depositing a layer of magnetic material that defines a first pole P1. A dual gap is formed on the first pole P1 by depositing a first layer of nonmagnetic material that defines two side gaps and part of a central gap interposed between the two side gaps. A second layer of nonmagnetic material is deposited on the first layer in order to further define the central gap. In its final configuration, the central gap is substantially wider than the two side gaps. Another layer of magnetic material is deposited over the central and side gaps for defining a second pole P2.
    Type: Grant
    Filed: May 15, 1996
    Date of Patent: March 31, 1998
    Assignee: Read-Rite Corporation
    Inventor: Daniel A. Nepela
  • Patent number: 5731937
    Abstract: A thin film magnetic transducer employs a giant magnetoresistive (GMR) sensing element operating in a (CPP) current-perpendicular-to-the-plane mode. Electrical lead members in electric contact with the sensing element provide for the flow of sensor current through the giant magnetoresistive element. The height, or both the height and the width, of the GMR sensing element are greater than the height, or both the height and width respectively, of the lead members, thereby resulting in an increased output signal from the transducer.
    Type: Grant
    Filed: August 22, 1997
    Date of Patent: March 24, 1998
    Assignee: Read-Rite Corporation
    Inventor: Samuel W. Yuan
  • Patent number: 5727308
    Abstract: A magnetic head is formed by depositing a pad pattern on a substrate with a flat upper surface. The pad pattern includes two spaced inner slopes that face each other. An air bearing surface plane is defined between the inner slopes where the air bearing surface of the magnetic head is to be formed. An undercoat layer is deposited on the pad pattern, such that the undercoat layer follows the contour of the inner slopes to form a recessed region between the inner slopes. A magnetic layer is deposited on the undercoat layer to form a first pole P1 that follows the contours of the inner slopes. A gap layer is then formed on top of the first pole P1 and follows its contour. Conductive coils are formed within the recessed region. A second magnetic layer is deposited over the coils and gap layer to form a second pole P2. The magnetic head is lapped at the air bearing surface plane to form the final air bearing surface.
    Type: Grant
    Filed: July 25, 1996
    Date of Patent: March 17, 1998
    Assignee: Read-Rite Corporation
    Inventors: Chak M. Leung, Charles R. Bond, Daniel A. Nepela
  • Patent number: 5726841
    Abstract: An air bearing magnetic head is formed with a trimmed head pole tip that includes first and second poles having first and second surfaces respectively, which are coplanar with the air bearing surface of the magnetic head. A pair of leading and trailing bevel surfaces are angularly formed with respect to the first and second surfaces respectively. The bevel surfaces retract portions of the head pole tip away from the surface of a storage medium, and render the head pole tip less sensitive to stray flux, resulting in readback data signals being practically free of undesirable signal undershoots and overshoots. In addition, a minute amount of pole material of the first and second surfaces are trimmed away, thereby defining stepped areas with narrow widths in the first and second poles. The stepped areas enable the magnetic head to record data with narrow and well defined track widths.
    Type: Grant
    Filed: June 11, 1996
    Date of Patent: March 10, 1998
    Assignee: Read-Rite Corporation
    Inventors: Hua-Ching Tong, Francis H. Liu, Samuel W. Yuan, Vernon M. Riedlin, Jr., Pradeep K. Thayamballi
  • Patent number: 5717550
    Abstract: A thin film magnetic head employs antiferromagnetic and ferromagnetic layers in a layered structure to provide magnetic exchange field coupling. This structure is provided with a buffer layer which is in contact with either the ferromagnetic layer or the antiferromagnetic layer and whose action enhances the exchange field coupling between the antiferromagnetic and ferromagnetic layers and improves the corrosion resistance.
    Type: Grant
    Filed: November 1, 1996
    Date of Patent: February 10, 1998
    Assignee: Read-Rite Corporation
    Inventors: Daniel A. Nepela, Marcos M. Lederman
  • Patent number: 5708358
    Abstract: A spin valve magnetoresistive sensor includes a substrate and a layered structure formed on the substrate. The layered structure includes a pair of thin film layers of ferromagnetic material separated from each other by a nonmagnetic spacer. The direction of magnetization of one of the thin film layers is pinned by a first permanent magnet layer. A second permanent magnet layer is located adjacent to the other of the thin film layers for longitudinal biasing purposes. The first permanent magnet layer has significantly higher coercivity than the second permanent magnet layer.
    Type: Grant
    Filed: March 21, 1996
    Date of Patent: January 13, 1998
    Assignee: Read-Rite Corporation
    Inventor: Durga P. Ravipati
  • Patent number: 5707538
    Abstract: A magnetoresitive transducer has an insulating gap layer of variable thickness. The transducer includes a magnetoresistive layer disposed in an active region, and a first magnetic shield layer disposed in the active region and a field region. An insulating layer is spaced between the magnetoresistive layer and the magnetic shield layer. The insulating layer is thinner in the active region than in the field region. The probability of other layers bridging through the insulating layer in the field region is substantially reduced. The method of forming the transducer includes depositing a first insulating layer above the magnetic layer, and then selectively etching the first insulating layer by forming an opening in the active region having a cross-sectional profile sloping inwardly toward the magnetic shield layer. Thereafter, an insulating layer is deposited atop the first insulating layer having the opening.
    Type: Grant
    Filed: July 28, 1995
    Date of Patent: January 13, 1998
    Assignee: Read-Rite Corporation
    Inventors: Yong Shen, T. C. Chuang
  • Patent number: 5705973
    Abstract: A giant magnetoresistive dual spin valve sensor employs at least one magnetic biasing layer located adjacent to an antiferromagnetic layer in the spin valve structure which includes two pinned ferromagnetic layers. The antiferromagnetic layer simultaneously pins the biasing layer and the ferromagnetic layer nearest the antiferromagnetic layer. This structure eliminates the bias point offset present in prior dual spin valve sensors.
    Type: Grant
    Filed: August 26, 1996
    Date of Patent: January 6, 1998
    Assignee: Read-Rite Corporation
    Inventors: Samuel W. Yuan, Hua-Ching Tong, Francis H. Liu, Minshen Tan
  • Patent number: 5704715
    Abstract: The air bearing surface of an air bearing slider is configured with a taper formed at the slider leading end and a rail that is formed with a base and two legs. One leg extends from the base partially toward the trailing end. The other leg extends from the base to the trailing end and is integrally formed of a rectangularly shaped section and one or more polygon-shaped sections. Inner and outer recesses are defined and separated by the rail, such that the slider is effectively insensitive to changes in ambient pressure, particularly from variations in altitude, so that a substantially constant flying height can be maintained.
    Type: Grant
    Filed: December 9, 1996
    Date of Patent: January 6, 1998
    Assignee: Read-Rite Corporation
    Inventors: Ciuter Chang, Yiao-Tee Hsia, Pablo G. Levi, Christopher A. Lee
  • Patent number: 5694276
    Abstract: A magnetic head assembly includes a magnetoresistive (MR) read sensor dielectrically disposed between a magnetic shield layer and a first pole layer. A write transducer comprises an inductive coil having a plurality of windings dielectrically disposed between the first pole layer and a second pole layer. The magnetic shield layer partially overlaps portions of the coil windings. A nonmagnetic layer is coplanar with the magnetic shield layer. A reduced coupling area between the magnetic shield layer and the coil decreases the mutual inductance applied to the magnetic coil by the magnetic layer, resulting in the coil having better response to write current and being capable of operating at wider frequency ranges. The first pole layer includes a unique shape having a narrow mid-section integrally formed between the wider end sections.
    Type: Grant
    Filed: July 1, 1996
    Date of Patent: December 2, 1997
    Assignee: Read-Rite Corporation
    Inventors: Yong Shen, Steven C. Rudy, Vincent D. Retort