Patents by Inventor Francis H. Liu

Francis H. Liu 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: 8537495
    Abstract: A method and system for providing a magnetic transducer are described. The magnetic transducer includes a first pole, a write gap, a second pole, a first coil, and a second coil. The first pole has a front portion on which at least a portion of the write gap resides. The second pole includes a split yoke that includes a first portion and a second portion. At least a portion of the first coil resides between the first portion of the split yoke and the first pole. At least a portion of the second coil resides between the second portion of the split yoke and the first pole.
    Type: Grant
    Filed: January 10, 2013
    Date of Patent: September 17, 2013
    Assignee: Western Digital (Fremont), LLC
    Inventors: Peng Luo, Zhigang Bai, Yugang Wang, Kroum S. Stoev, Francis H. Liu
  • Patent number: 8514506
    Abstract: A disk drive is disclosed comprising a disk having a plurality of data tracks, and a head actuated over the disk, the head comprising a first read element and a second read element. A data track is read to generate a first read signal emanating from the first read element and a second read signal emanating from the second read element. The first read signal is delayed in continuous time relative to the second read signal to generate a delayed read signal, and the second read signal is combined with the delayed read signal to generate a combined read signal. An estimated data sequence is detected from the combined read signal.
    Type: Grant
    Filed: February 10, 2012
    Date of Patent: August 20, 2013
    Assignee: Western Digital (Fremont), LLC
    Inventors: Shaoping Li, Yimin Guo, Francis H. Liu, Sining Mao
  • Patent number: 8385157
    Abstract: A method and system for writing data to a media utilizing an energy assisted magnetic recording (EAMR) head are described. The EAMR head includes at least one laser and at least one EAMR transducer. The laser(s) provide energy. The EAMR transducer(s) are coupled with the laser. The EAMR transducer(s) are configured to direct the energy to spot(s) on the media and to write a plurality of tracks of data in a block. The method and system include writing a track of the plurality of tracks on the media within the spot(s) using the EAMR transducer and stepping a track pitch along a particular radial direction on the media. The method and system also include repeating the writing and stepping steps until the plurality of tracks for the block is written.
    Type: Grant
    Filed: September 30, 2009
    Date of Patent: February 26, 2013
    Assignee: Western Digital Technologies, Inc.
    Inventors: Eric J. Champion, Francis H. Liu, Adam F. Torabi
  • Patent number: 8373945
    Abstract: A method and system for providing a magnetic transducer are described. The magnetic transducer includes a first pole, a write gap, a second pole, a first coil, and a second coil. The first pole has a front portion on which at least a portion of the write gap resides. The second pole includes a split yoke that includes a first portion and a second portion. At least a portion of the first coil resides between the first portion of the split yoke and the first pole. At least a portion of the second coil resides between the second portion of the split yoke and the first pole.
    Type: Grant
    Filed: April 23, 2007
    Date of Patent: February 12, 2013
    Assignee: Western Digital (Fremont), LLC
    Inventors: Peng Luo, Zhigang Bai, Yugang Wang, Kroum S. Stoev, Francis H. Liu
  • Patent number: 8139301
    Abstract: A disk drive is disclosed comprising a disk having a plurality of data tracks, and a head actuated over the disk, the head comprising a first read element and a second read element. A data track is read to generate a first read signal emanating from the first read element and a second read signal emanating from the second read element. The first read signal is delayed relative to the second read signal to generate a delayed read signal, and the second read signal is combined with the delayed read signal to generate a combined read signal. An estimated data sequence is detected from the combined read signal.
    Type: Grant
    Filed: July 22, 2009
    Date of Patent: March 20, 2012
    Assignee: Western Digital (Fremont), LLC
    Inventors: Shaoping Li, Yimin Guo, Francis H. Liu, Sining Mao
  • Patent number: 7688546
    Abstract: The method and system provide a perpendicular magnetic recording (PMR) head having an air bearing surface (ABS). The PMR head includes first and second poles each having front and back gap regions, a first nonmagnetic insertion layer between the back gap regions, a magnetic pole layer with a front terminating at the ABS, a write gap, shield(s), a second nonmagnetic insertion layer between the second pole back gap region and the shield(s), and coil(s) between the shield(s) and the first pole. The magnetic pole layer terminates between the ABS and the second pole back gap region and has pole angle(s) of at least thirty and not more than fifty degrees. At least part of the magnetic pole layer resides on the second pole. Part of the shield(s) are adjacent to the write gap. Another part of the shield(s) is coupled with the second pole back gap region.
    Type: Grant
    Filed: December 21, 2006
    Date of Patent: March 30, 2010
    Assignee: Western Digital (Fremont), LLC
    Inventors: Zhigang Bai, Peng Luo, Kroum S. Stoev, Francis H. Liu, Yugang Wang, Adam F. Torabi
  • Patent number: 7660080
    Abstract: A read/write head for use in a data storage device to control the low dynamic flying height in order to achieve high data recording storage capacity of magnetic hard drives. The read/write head is designed for use in a data storage device that includes a storage medium having a recording surface. The head comprises a pole tip region and an actuator. In turn, the actuator includes an excitation source for generating a magnetic field, and a magnetostrictive plate for expanding in response to the magnetic field, resulting in a protrusion in a section of the pole tip region along a direction towards the recording surface, so that the head flies above the recording surface at a flying height lower than a nominal flying height.
    Type: Grant
    Filed: April 30, 2004
    Date of Patent: February 9, 2010
    Assignee: Western Digital (Fremont), LLC
    Inventors: Francis H. Liu, Kroum S. Stoev, Yugang Wang
  • Patent number: 7522379
    Abstract: A head including a write element for writing data to a magnetic media, and methods for its production are provided. A write element of the invention includes one or more of a recessed first pole, a heat sink layer, and a shortened yoke length. A method of the invention provides forming an anti-reflective layer before forming a mask layer. During photolithography the anti-reflective layer suppresses undesirable reflections off of features, such as vertical sidewalls, that otherwise limit how closely to such features portions of the mask layer can be formed.
    Type: Grant
    Filed: July 30, 2004
    Date of Patent: April 21, 2009
    Assignee: Western Digital (Fremont), LLC
    Inventors: Mohamad T. Krounbi, Yining Hu, Ming Zhao, Kenneth Kung, Mark D. Thomas, Kroum S. Stoev, Francis H. Liu, Marcos M. Lederman
  • Patent number: 7508627
    Abstract: A method and system for providing a magnetic recording transducer are disclosed. The method and system include providing a metallic underlayer directly on a portion of an insulating layer. The method and system also include forming a perpendicular magnetic recording pole on the metallic underlayer. The perpendicular magnetic recording pole has a top, a bottom narrower than the top, and sides. The perpendicular magnetic recording pole has a pole removal rate. The method and system also include providing an insulator having an insulator removal rate. The insulator substantially surrounds at least the sides of the perpendicular magnetic recording pole. The metallic underlayer has a removal rate that is at least one of less than the insulator removal rate and substantially equal to the pole removal rate.
    Type: Grant
    Filed: March 3, 2006
    Date of Patent: March 24, 2009
    Assignee: Western Digital (Fremont), LLC
    Inventors: Lei Larry Zhang, Danning Yang, Honglin Zhu, Ki Sup Chung, Francis H. Liu, Yingjiang Chen
  • Patent number: 7443632
    Abstract: A magnetic head is disclosed that has first and second substantially flat soft magnetic pole layers that are magnetically coupled together in a backgap region that is removed from the medium-facing surface; a soft magnetic pedestal having a leading edge and a trailing edge, the trailing edge adjoining the second pole layer adjacent to the medium-facing surface, the leading edge defining a throat area that is spaced from the first pole layer by a submicron nonferromagnetic gap and defining an apex area that is spaced from the first pole layer by a greater separation than the gap, the throat area meeting the apex area at a throat height; and a plurality of substantially parallel, electrically conductive sections disposed between the first and second pole layers, the conductive sections disposed in a single layer that is aligned along a plane that intersects the pedestal and the backgap region.
    Type: Grant
    Filed: July 19, 2007
    Date of Patent: October 28, 2008
    Assignee: Western Digital (Fremont), LLC
    Inventors: Kroum S. Stoev, Francis H. Liu, Yugang Wang
  • Patent number: 7375926
    Abstract: A magnetic head for writing information on a relatively-moving medium includes a first substantially flat soft magnetic pole layer and a second substantially flat pole layer with at least one coil layer between them. The pole layers are magnetically coupled in a core region and spaced by more than one micron from one other. A soft magnetic pedestal adjoins the first pole layer adjacent to a medium-facing surface of the head, and a first high magnetic saturation layer adjoins the pedestal. A second high magnetic saturation layer adjoins the second pole layer. The first high magnetic saturation layer has a first throat height and the second high magnetic saturation layer extends from the medium-facing surface only to a second throat height. The first and second throat heights are within about one and one-half microns from the medium-facing surface and are essentially equal.
    Type: Grant
    Filed: July 18, 2007
    Date of Patent: May 20, 2008
    Assignee: Western Digital (Fremont), LLC
    Inventors: Kroum S. Stoev, Francis H. Liu, Yugang Wang, Yingjian Chen
  • Patent number: 7337530
    Abstract: A method of making a perpendicular magnetic recording head for use in a data storage device includes forming a first pole layer, a second pole layer, a third pole layer, and a shield layer of a write section. The first pole layer, second pole layer, third pole layer, and shield layer are formed without using a chemical mechanical polishing process. The method next includes concurrently trimming the shield layer and a write pole that is defined by the third pole layer to a predetermined track width. In the trimming step, the shield layer is used as a mask for the write pole.
    Type: Grant
    Filed: January 30, 2007
    Date of Patent: March 4, 2008
    Assignee: Western Digital (Fremont), LLC
    Inventors: Kroum S. Stoev, Francis H. Liu, Yugang Wang
  • Patent number: 7310204
    Abstract: A magnetic head for writing information on a relatively-moving medium has a pair of substantially flat soft magnetic pole layers separated by a pair of coil layers. A soft magnetic pedestal adjoins the leading pole layer adjacent to a medium-facing surface and is spaced from the second pole layer by a nanoscale nonferromagnetic gap, the pedestal having a layer of high magnetic saturation material that defines a throat height and extends beyond the throat height. A second high magnetic saturation material adjoins the trailing pole layer and either terminates at the throat height to form a second pedestal or extends to reach a magnetic backgap structure that magnetically couples the pole layers. The MR sensor can be located closer than the write transducer to the trailing end of the head to reduce separation between the read transducer and the write transducer.
    Type: Grant
    Filed: December 19, 2003
    Date of Patent: December 18, 2007
    Assignee: Western Digital (Fremont), LLC
    Inventors: Kroum S. Stoev, Francis H. Liu, Yugang Wang, Yingjian Chen
  • Patent number: 7292409
    Abstract: A magnetic head for a disk drive is disclosed that has a first soft magnetic pole layer disposed in the head adjacent to a medium-facing surface and extending perpendicular to the medium-facing surface; a second soft magnetic pole layer disposed closer than the first pole layer to the trailing end, the second pole layer magnetically coupled to the first pole layer in a backgap region; a soft magnetic pedestal adjoining the second pole layer, disposed closer than the second pole layer to the medium-facing surface and extending less than the second pole layer extends from the medium-facing surface, the pedestal separated from the first pole layer by a nonferromagnetic gap, the pedestal having a thickness that is less than four hundred and fifty nanometers between the gap and the second pole layer. Longitudinal and perpendicular recording embodiments are disclosed, as well as solenoidal, single-layer and dual-layer reversed-current coil structures.
    Type: Grant
    Filed: February 27, 2004
    Date of Patent: November 6, 2007
    Assignee: Western Digital (Fremont), LLC
    Inventors: Kroum S. Stoev, Francis H. Liu, James H. Wang, Marcos M. Lederman, David J. Seagle
  • Patent number: 7283327
    Abstract: A magnetic write head includes a magnetic yoke having a first pole and a second pole. The first pole and the second pole each terminate at an air bearing surface. The first pole is magnetically coupled to the second pole in a backgap region. The magnetic write head further includes a electrically conductive write coil magnetically coupled to the magnetic yoke. The magnetic write head further includes a resistive heater coil having a first coil turn and a second coil turn. The heater coil is electrically isolated from the write coil. At least a portion of the first coil turn is between the first pole and the second pole and between the air bearing surface and the backgap region. At least a portion of the second coil turn is between the first pole and the second pole and between the air bearing surface and the backgap region. The portion of the first coil turn overlaps the portion of the second coil turn.
    Type: Grant
    Filed: June 13, 2006
    Date of Patent: October 16, 2007
    Assignee: Western Digital (Fremont), LLC
    Inventors: Francis H. Liu, Kroum S. Stoev, Mohamad T. Krounbi
  • Patent number: 7248433
    Abstract: A magnetic head is disclosed that has first and second substantially flat soft magnetic pole layers that are magnetically coupled together in a backgap region that is removed from the medium-facing surface; a soft magnetic pedestal having a leading edge and a trailing edge, the trailing edge adjoining the second pole layer adjacent to the medium-facing surface, the leading edge defining a throat area that is spaced from the first pole layer by a submicron nonferromagnetic gap and defining an apex area that is spaced from the first pole layer by a greater separation than the gap, the throat area meeting the apex area at a throat height; and a plurality of substantially parallel, electrically conductive sections disposed between the first and second pole layers, the conductive sections disposed in a single layer that is aligned along a plane that intersects the pedestal and the backgap region.
    Type: Grant
    Filed: February 2, 2004
    Date of Patent: July 24, 2007
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kroum S Stoev, Francis H Liu, Yugang Wang
  • Patent number: 7239478
    Abstract: A write element for perpendicular recording in a data storage system is fabricated to maintain the thickness of a side shield at both edges of a pole P3, and to form the pole P3 in a trapezoidal shape. Forming a side shield around the pole P3 removes stray fields, creating a quiet, noise-free write element and preventing side erasure. The fabrication method utilizes a magnetic buffer layer to protect a shield gap during trim of the pole P3, and thus to provide the shield gap with a uniform thickness. The magnetic buffer layer also protects the shield gap and pole P3 when the top hard mask is removed. Consequently, the write field is made uniform across the track width. The fabrication method uses a metal in the shield gap to improve the pole geometry after pole trim and to provide a uniform edge to the pole P3.
    Type: Grant
    Filed: January 31, 2004
    Date of Patent: July 3, 2007
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kyusik Sin, Yinshi Liu, Benjamin Chen, Francis H. Liu
  • Patent number: 7212384
    Abstract: A read element includes a magnetoresistive sensor having a side and an upper surface that defines an edge. An underlayer overlies the side of the magnetoresistive sensor, and a hard bias layer overlies at least part of the underlayer and defines a hard bias junction with the underlayer. A lead is formed atop the hard bias layer. The hard bias junction is recessed from the edge of the magnetoresistive sensor by a predetermined recess distance, to provide stability and sensitivity to the read element.
    Type: Grant
    Filed: February 27, 2004
    Date of Patent: May 1, 2007
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kroum S. Stoev, Amritpal S. Rana, Francis H. Liu
  • Patent number: 7193815
    Abstract: A read/write head for use in a perpendicular magnetic recording head in a data storage system. The read/write head includes a write section that is comprised of a first pole layer, a second pole layer, a third pole layer, and a shield layer. The third pole layer defines a write pole tip, and the third pole layer and the shield layer are separated from each other to define a write gap therebetween. At least part of the shield layer has a generally uniform width, and wherein the write pole tip defines a track width that is substantially equal to the uniform width of the shield layer. According to one embodiment the entire shield layer has a generally uniform width that is substantially equal to the track width. According to another embodiment, the shield layer includes a lower section and an upper section, wherein the lower section has a generally uniform width along its entire length, and wherein the upper section is wider than the lower section.
    Type: Grant
    Filed: April 6, 2004
    Date of Patent: March 20, 2007
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kroum S. Stoev, Francis H. Liu, Yugang Wang
  • Patent number: 7126788
    Abstract: A magnetic head for writing information on perpendicular media has a write pole tip, a return pole tip and a deflection pole tip is disclosed. The return pole tip has a media-facing area at least two orders of magnitude greater than that of the write pole tip, and the deflection pole tip is spaced from a trailing corner of the write pole tip by a submicron nonferromagnetic gap. Magnetic flux emanating from the write pole tip is strongest adjacent the trailing corner and directed at an angle that is not perpendicular to the write pole tip. The angled flux provides increased torque to rotate magnetic dipoles in the adjacent media layer that are oriented substantially perpendicular to the disk surface. The media may have a soft magnetic underlayer that is spaced from the write pole tip by a distance similar to the gap spacing.
    Type: Grant
    Filed: November 26, 2003
    Date of Patent: October 24, 2006
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Francis H. Liu, Kroum S. Stoev, Yugang Wang