Patents by Inventor Prakash Kasiraj

Prakash Kasiraj 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).

  • Patent number: 9472211
    Abstract: A magnetic recording system configured for recording to a bit patterned media using both hypertrack recording and shingled recording. The magnetic recording system includes a write pole with a notched trailing edge that results in a write bubble with a trailing edge that has two outer convex lobes separated by a centrally disposed concave region. By locating one of the lobes over first and second data tracks of a hypertrack, a proper alignment of the relative phase of the two tracks can be maintained. Further adjustment to the alignment can be achieved by adjusting the radial location of the write head.
    Type: Grant
    Filed: September 8, 2014
    Date of Patent: October 18, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Thomas R. Albrecht, Prakash Kasiraj
  • Publication number: 20140376124
    Abstract: A magnetic recording system configured for recording to a bit patterned media using both hypertrack recording and shingled recording. The magnetic recording system includes a write pole with a notched trailing edge that results in a write bubble with a trailing edge that has two outer convex lobes separated by a centrally disposed concave region. By locating one of the lobes over first and second data tracks of a hypertrack, a proper alignment of the relative phase of the two tracks can be maintained. Further adjustment to the alignment can be achieved by adjusting the radial location of the write head.
    Type: Application
    Filed: September 8, 2014
    Publication date: December 25, 2014
    Applicant: HGST NETHERLANDS B.V.
    Inventors: Thomas R. Albrecht, Prakash Kasiraj
  • Patent number: 8848314
    Abstract: A magnetic recording system configured for recording to a bit patterned media using both hypertrack recording and shingled recording. The magnetic recording system includes a write pole with a notched trailing edge that results in a write bubble with a trailing edge that has two outer convex lobes separated by a centrally disposed concave region. By locating one of the lobes over first and second data tracks of a hypertrack, a proper alignment of the relative phase of the two tracks can be maintained. Further adjustment to the alignment can be achieved by adjusting the radial location of the write head.
    Type: Grant
    Filed: December 7, 2011
    Date of Patent: September 30, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Thomas R. Albrecht, Prakash Kasiraj
  • Patent number: 8786969
    Abstract: In one embodiment, a magnetic data storage system includes a bit patterned magnetic medium, wherein centers of bits in adjacent data tracks do not lie on a common line in a cross-track direction, a magnetic head having a writer element having a width greater than a width of a data track in a track width direction adapted for writing data successively to at least two adjacent data tracks of the magnetic medium, and a reader element having a width larger than the width of a data track in the track width direction adapted for reading data concurrently from the at least two adjacent data tracks of the magnetic medium in a single pass, a drive mechanism for passing the magnetic medium over the magnetic head, and a controller electrically coupled to the magnetic head for controlling operation of the magnetic head.
    Type: Grant
    Filed: September 30, 2011
    Date of Patent: July 22, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Prakash Kasiraj, Thomas R. Albrecht
  • Publication number: 20130148228
    Abstract: A magnetic recording system configured for recording to a bit patterned media using both hypertrack recording and shingled recording. The magnetic recording system includes a write pole with a notched trailing edge that results in a write bubble with a trailing edge that has two outer convex lobes separated by a centrally disposed concave region. By locating one of the lobes over first and second data tracks of a hypertrack, a proper alignment of the relative phase of the two tracks can be maintained. Further adjustment to the alignment can be achieved by adjusting the radial location of the write head.
    Type: Application
    Filed: December 7, 2011
    Publication date: June 13, 2013
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Thomas R. Albrecht, Prakash Kasiraj
  • Publication number: 20130083416
    Abstract: In one embodiment, a magnetic data storage system includes a bit patterned magnetic medium, wherein centers of bits in adjacent data tracks do not lie on a common line in a cross-track direction, a magnetic head having a writer element having a width greater than a width of a data track in a track width direction adapted for writing data successively to at least two adjacent data tracks of the magnetic medium, and a reader element having a width larger than the width of a data track in the track width direction adapted for reading data concurrently from the at least two adjacent data tracks of the magnetic medium in a single pass, a drive mechanism for passing the magnetic medium over the magnetic head, and a controller electrically coupled to the magnetic head for controlling operation of the magnetic head.
    Type: Application
    Filed: September 30, 2011
    Publication date: April 4, 2013
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Prakash Kasiraj, Thomas R. Albrecht
  • Patent number: 7490212
    Abstract: Data is written to a hard disk drive using shingled writing principles, i.e., each data track is partially overwritten when an immediately contiguous data track is written. Two or more contiguous data tracks establish a band, and a band may store data from one and only one file, such as an AV file.
    Type: Grant
    Filed: September 29, 2003
    Date of Patent: February 10, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Prakash Kasiraj, Richard M. H. New, Jorge Campello de Souza, Mason Lamar Williams
  • Patent number: 7360296
    Abstract: A process is described for fabricating sliders with reduced lapping damage to the hard-bias materials. The stack of layers for the magnetic sensor is deposited on a wafer and patterned into an initial shape. The hard-bias structures are fabricated at the side of the magnetic sensor as in the prior art. In each of the two described embodiments of the invention, the hard-bias material below the ABS is reduced or removed and replaced with a fill material such as alumina. A first embodiment reduces the hard-bias material below the ABS by forming an extended lapping gap along the ABS in both the sensor and hard-bias material. A second embodiment forms a photoresist mask over the sensor and the portion of the hard-bias/lead structures above the ABS and the exposed hard-bias/lead material below the ABS is thinned or completely removed by milling.
    Type: Grant
    Filed: September 30, 2004
    Date of Patent: April 22, 2008
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Marie-Claire Cyrille, Prakash Kasiraj, Huey-Ming Tzeng
  • Patent number: 7313858
    Abstract: A Damascene process is provided for manufacturing a coil structure for a magnetic head. During the manufacturing process, an insulating layer is initially deposited after which a photoresist layer is deposited. A silicon dielectric layer is then deposited on the photoresist layer. After masking the silicon dielectric layer, at least one channel is etched in the photoresist layer and the silicon dielectric layer. Then, a conductive seed layer is deposited in the at least one channel. The at least one channel is then ready to be filled with a conductive material and chemically/mechanically polished to define a coil structure.
    Type: Grant
    Filed: March 31, 2004
    Date of Patent: January 1, 2008
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Richard Hsiao, Prakash Kasiraj, Quang Le, Paul Phong Nguyen, Son Van Nguyen, Denny D. Tang, Patrick Rush Webb
  • Patent number: 7304821
    Abstract: A Damascene process is provided for manufacturing a coil structure for a magnetic head. During the manufacturing process, an insulating layer is initially deposited after which a photoresist layer is deposited. A silicon dielectric layer is then deposited on the photoresist layer. After masking the silicon dielectric layer, at least one channel is etched in the photoresist layer and the silicon dielectric layer. Then, a conductive seed layer is deposited in the at least one channel. The at least one channel is then ready to be filled with a conductive material and chemically/mechanically polished to define a coil structure.
    Type: Grant
    Filed: November 19, 2003
    Date of Patent: December 4, 2007
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Richard Hsiao, Prakash Kasiraj, Quang Le, Paul Phong Nguyen, Son Van Nguyen, Denny D. Tang, Patrick Rush Webb
  • Patent number: 7262936
    Abstract: A heating device for a magnetic recording head includes first and second separating layers, the first separating layer having preferably a higher or equal thermal resistance than the first separating layer, and a heater formed between the first and second separating layers. A magnetic recording head for recording on magnetic medium includes a heating device which generates a heat spot on the magnetic medium which is larger than a magnetic track width, and/or heats a portion of the magnetic recording head which is on a leading edge side of a write gap in the magnetic recording head.
    Type: Grant
    Filed: March 1, 2004
    Date of Patent: August 28, 2007
    Assignee: Hitachi Global Storage Technologies Netherlands, B.V.
    Inventors: Hendrik F. Hamann, Prakash Kasiraj, Jeffrey S. Lille, Yves C. Martin, Chie Ching Poon, Neil Leslie Robertson, Jan-Ulrich Thiele, Hemantha Kumar Wickramasinghe
  • Patent number: 7199986
    Abstract: A magnetic sensor is provided, having two bias layers separated by a decoupling layer to eliminate exchange coupling between the bias layers. The two bias layers may have differing coercivities, such that the biases provided by the bias layers to the free layer are independently adjustable. The grain structures of the two bias layers may be substantially decorrelated by the decoupling layer.
    Type: Grant
    Filed: February 18, 2004
    Date of Patent: April 3, 2007
    Assignee: Hitachi Global Storage Technologies
    Inventors: Marie-Claire Cyrille, Meng Ding, Kuok-San Ho, Prakash Kasiraj, Ernesto Marinero, James Lamar Nix, Brian York
  • Patent number: 7196878
    Abstract: A spin valve (SV) sensor of the self-pinned type includes one or more compressive stress modification layers for reducing the likelihood that the pinning field will flip its direction. The spin valve sensor includes a capping layer formed over a spin valve structure which includes a free layer, an antiparallel (AP) self-pinned layer structure, and a spacer layer in between the free layer and the AP self-pinned layer structure. A compressive stress modification layer is formed above or below the capping layer, adjacent the AP self-pinned layer structure, or both. Preferably, the compressive stress modification layer is made of ruthenium (Ru) or other suitable material.
    Type: Grant
    Filed: February 27, 2004
    Date of Patent: March 27, 2007
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Ciaran Avram Fox, Hardayal Singh Gill, Prakash Kasiraj, Wen-Yaung Lee, Mustafa Michael Pinarbasi
  • Patent number: 7161763
    Abstract: Magnetic data storage devices use read/write heads to transfer data between the magnetic storage medium and the rest of the system. The read head is constructed with a magnetic layer called a free layer whose magnetic axis rotates based upon external magnetic influences of the magnetic storage medium. The free layer is biased into a predetermined magnetic orientation with the magnetic influence of a layer called a hard bias layer. Orientation of magnetic axes within the hard bias layer is desired. This document describes a hard bias layer whose magnetization exhibits uniaxial magnetic anisotropy.
    Type: Grant
    Filed: February 18, 2004
    Date of Patent: January 9, 2007
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Kuok San Ho, Prakash Kasiraj, Ernesto E. Marinero, James L. Nix
  • Patent number: 7072156
    Abstract: A magnetic sensor is provided, having two bias layers separated by a decoupling layer to eliminate exchange coupling between the bias layers. The two bias layers may have differing coercivities, such that the biases provided by the bias layers to the free layer are independently adjustable. The grain structures of the two bias layers may be substantially decorrelated by the decoupling layer.
    Type: Grant
    Filed: February 18, 2004
    Date of Patent: July 4, 2006
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Marie-Claire Cyrille, Meng Ding, Kuok San Ho, Prakash Kasiraj, Ernesto Marinero, James Lamar Nix
  • Patent number: 7057862
    Abstract: A current-perpendicular-to-the-plane (CPP) magnetoresistive sensor has additional layers for stabilizing the free layer against sense-current-generated magnetic fields. A ferromagnetic stabilizing layer is spaced from the free layer by a spacer layer and is exchange coupled with a second antiferromagnetic layer, the first antiferromagnetic layer being the conventional one for pinning the pinned layer in the CPP sensor. The stabilizing layer is in a vortex or other non-longitudinal magnetization pattern that is fixed by exchange coupling with the second antiferromagnetic layer. The stabilizing layer is also ferromagnetically coupled to the free layer across the spacer layer so that in the absence of both a sense current and an external magnetic field, the free and stabilization layers have similarly shaped vortex or other non-longitudinal magnetization patterns.
    Type: Grant
    Filed: February 10, 2004
    Date of Patent: June 6, 2006
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Prakash Kasiraj, Stefan Maat
  • Publication number: 20060064866
    Abstract: A process is described for fabricating sliders with reduced lapping damage to the hard-bias materials. The stack of layers for the magnetic sensor is deposited on a wafer and patterned into an initial shape. The hard-bias structures are fabricated at the side of the magnetic sensor as in the prior art. In each of the two described embodiments of the invention, the hard-bias material below the ABS is reduced or removed and replaced with a fill material such as alumina. A first embodiment reduces the hard-bias material below the ABS by forming an extended lapping gap along the ABS in both the sensor and hard-bias material. A second embodiment forms a photoresist mask over the sensor and the portion of the hard-bias/lead structures above the ABS and the exposed hard-bias/lead material below the ABS is thinned or completely removed by milling.
    Type: Application
    Filed: September 30, 2004
    Publication date: March 30, 2006
    Inventors: Marie-Claire Cyrille, Prakash Kasiraj, Huey-Ming Tzeng
  • Patent number: 7014530
    Abstract: A slider is described with a resistive electro-lapping guide (ELG), which is aligned with a structure in the write head such as the throat height or trailing shield thickness and extends from the lapping region through the ABS and is connected to pads on the surface of the slider. In a second embodiment the ELG is disposed entirely in the section of the slider which will be removed by lapping. Another embodiment of the invention is a system for single slider lapping which simultaneously monitors the resistance of the read sensor or a read head ELG and at least one ELG that is aligned with a structure in the write head. A controller uses the resistance information to implement an algorithm which decides when lapping should be terminated.
    Type: Grant
    Filed: September 29, 2003
    Date of Patent: March 21, 2006
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Prakash Kasiraj, Quang Le, Huey Tzeng, Xiao Z. Wu
  • Patent number: 6967810
    Abstract: Data is written to a hard disk drive using shingled writing principles, i.e., each data track is partially overwritten when an immediately contiguous data track is written. Two or more contiguous data tracks establish a band, and a band may store data from an AV file. Tracks may be written in sequence toward or away from the inside diameter (ID) of the disk, depending on their radial location on the disk and the skew of the write element.
    Type: Grant
    Filed: September 29, 2003
    Date of Patent: November 22, 2005
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Prakash Kasiraj, Mason Lamar Williams
  • Publication number: 20050190496
    Abstract: A heating device for a magnetic recording head includes first and second separating layers, the first separating layer having preferably a higher or equal thermal resistance than the first separating layer, and a heater formed between the first and second separating layers. A magnetic recording head for recording on magnetic medium includes a heating device which generates a heat spot on the magnetic medium which is larger than a magnetic track width, and/or heats a portion of the magnetic recording head which is on a leading edge side of a write gap in the magnetic recording head.
    Type: Application
    Filed: March 1, 2004
    Publication date: September 1, 2005
    Inventors: Hendrik Hamann, Prakash Kasiraj, Jeffrey Lille, Yves Martin, Chie Poon, Neil Robertson, Jan-Ulrich Thiele, Hemantha Wickramasinghe