Patents by Inventor Durga P. Ravipati
Durga P. Ravipati has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6775902Abstract: A magnetic head is fabricated by providing a substrate with a planar surface, forming at least one cavity in the planar substrate, depositing a second yoke layer in the cavity, forming a second pole tip in the cavity in contact with the second yoke layer, patterning an inductive coil in the cavity, depositing a gap layer over the second pole tip, sputtering a first pole tip over the gap layer, etching the first and second pole tips and the gap layer to form a stack of layers, depositing a protective layer over the stack of layers, leveling the protective layer to expose the first pole tip, and patterning a first yoke layer in contact with the first pole tip.Type: GrantFiled: June 9, 2000Date of Patent: August 17, 2004Assignee: Western Digital (Fremont) Inc.Inventors: Yiming Huai, Durga P. Ravipati, Mark D. Thomas, Carlos Corona, William D. Jensen
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Patent number: 6504676Abstract: A magnetic head includes pole tips with aligned sidewalls and a low head profile. The aligned sidewalls are formed by depositing a stack of pole tip layers on a substrate. The stack of layers are etched through a common overlying mask. The stack of layers is covered over and around with a protective layer which is then planarized such that the stack of layers is exposed. The protective layer is etched to a predetermined thickness above the substrate, which is thinner than the thickness of the stack of layers. An inductive coil layer is deposited on the etched protective layer and covered with an overlying magnetic yoke layer which is dielectrically separated from the coil layer. The yoke layer thus formed assumes a low profile curvature due to the thin structure of the protective layer on the substrate.Type: GrantFiled: December 10, 1999Date of Patent: January 7, 2003Assignee: Read-Rite CorporationInventors: Hugh C. Hiner, Billy Wayne Crue, William D. Jensen, Lien-Chang Wang, Durga P. Ravipati
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Patent number: 6118629Abstract: A magnetic head includes first and second pole tip layers separated by a nonmagnetic gap layer. The pole tips are made of a high magnetic moment material. The right side walls of the first and second pole tips are vertically aligned with each other. Similarly, the left side walls of the first and second pole tips are vertically aligned with one another. The side fringing flux from one pole tip to another is substantially reduced resulting in a magnetic head capable of writing data tracks with well defined boundaries. The possibility of the pole tips operating in magnetic saturation is reduced because the pole tips, formed of high magnetic moment material, is capable of accommodating high coercive force. The magnetic head can be fabricated as an inverted head or a non-inverted head capable of writing on magnetic media with high coercivity and at a high data transfer rate.Type: GrantFiled: June 15, 1999Date of Patent: September 12, 2000Assignee: Read-Rite CorporationInventors: Yiming Huai, Durga P. Ravipati, Mark D. Thomas, Carlos Corona, William D. Jensen
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Patent number: 6032353Abstract: A magnetic head includes pole tips with aligned sidewalls and a low head profile. The aligned sidewalls are formed by depositing a stack of pole tip layers on a substrate. The stack of layers are etched through a common overlying mask. The stack of layers is covered over and around with a protective layer which is then planarized such that the stack of layers is exposed. The protective layer is etched to a predetermined thickness above the substrate, which is thinner than the thickness of the stack of layers. An inductive coil layer is deposited on the etched protective layer and covered with an overlying magnetic yoke layer which is dielectrically separated from the coil layer. The yoke layer thus formed assumes a low profile curvature due to the thin structure of the protective layer on the substrate.Type: GrantFiled: May 15, 1997Date of Patent: March 7, 2000Assignee: Read-Rite CorporationInventors: Hugh C. Hiner, Billy Wayne Crue, William D. Jensen, Lein-Chang Wang, Durga P. Ravipati
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Patent number: 5966800Abstract: A method of making a magnetic head which includes first and second pole tip layers separated by a nonmagnetic gap layer includes making the pole tips of a high magnetic moment material. The right side walls of the first and second pole tips are vertically aligned with each other. Similarly, the left side walls of the first and second pole tips are vertically aligned with one another. The side fringing flux from one pole tip to another is substantially reduced resulting in a magnetic head capable of writing data tracks with well defined boundaries. The possibility of the pole tips operating in magnetic saturation is reduced because the pole tips, formed of high magnetic moment material, is capable of accommodating high coercive force. The magnetic head can be fabricated as an inverted head or a non-inverted head capable of writing on magnetic media with high coercivity and at a high data transfer rate.Type: GrantFiled: July 28, 1997Date of Patent: October 19, 1999Assignee: Read-Rite CorporationInventors: Yiming Huai, Durga P. Ravipati, Mark D. Thomas, Carlos Corona, William D. Jensen
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Patent number: 5928715Abstract: A magnetoresistive read transducer includes a magnetoresistive (MR) layer having end regions spaced by a central active region. A pair of hard magnetic layers provide longitudinal magnetic bias to the MR layer, with each of the hard magnetic bias layers disposed in contact with one of the end regions of the MR layer. A pair of electrical lead members are disposed in contact with the end regions of the MR layer and with the hard magnetic bias layers. The hard magnetic bias layers and the electrical lead members are deposited, followed by selective removal of portions of the lead members to expose the edges of the hard bias material.Type: GrantFiled: July 28, 1997Date of Patent: July 27, 1999Assignee: Read-Rite CorporationInventors: Durga P. Ravipati, Steven Clark Rudy
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Patent number: 5838521Abstract: A magnetoresistive read transducer includes a magnetoresistive layer that is sandwiched between a pair of laminated magnetic shields. Each laminated magnetic shield includes at least two layers of ferromagnetic material spaced by a layer of non-magnetic material. The respective magnetization vectors of uniaxial anisotropy in the shields are opposite to each other. The magnetization vectors in the two ferromagnetic layers form a closed magnetic path which is substantially perpendicular to the surfaces of the layer interfaces. The magnetic pattern thus formed is highly stable, so that the magnetoresistive layer generates output signals with low Barkhausen noise and further allows the transducer to interact with recording media having high linear recording density.Type: GrantFiled: April 17, 1995Date of Patent: November 17, 1998Assignee: Read-Rite CorporationInventor: Durga P. Ravipati
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Patent number: 5739990Abstract: 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: GrantFiled: November 13, 1996Date of Patent: April 14, 1998Assignee: Read-Rite CorporationInventors: Durga P. Ravipati, Samuel W. Yuan
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Patent number: 5708358Abstract: 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: GrantFiled: March 21, 1996Date of Patent: January 13, 1998Assignee: Read-Rite CorporationInventor: Durga P. Ravipati
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Patent number: 5434826Abstract: A magnetoresistive transducer includes a magnetoresistive layer having end portions spaced by a central active portion. The longitudinal bias for the magnetoresistive layer is cooperatively furnished by a pair of hard magnetic bias regions. Each of the two hard magnetic bias regions includes a plurality of magnetized layers and each bias region is disposed in contact with one of the end portions of the magnetoresistive transducer. The magnetic flux required for the magnetoresistive layer to maintain a single domain state is adequately provided by the hard magnetic bias regions. In one embodiment, a substantially uniform thickness for the entire transducer is achieved, allowing the longitudinal bias to be continuously supplied to the magnetoresistive layer. In another embodiment, thinner hard magnetic bias regions provide improved step coverage for the second read gap thereby increasing yield. Also the thinner hard magnetic bias regions provide a significant increase of planarization of the write poles.Type: GrantFiled: September 26, 1994Date of Patent: July 18, 1995Assignee: Read-Rite CorporationInventors: Durga P. Ravipati, Yong Shen