Patents by Inventor Dongming Liu

Dongming 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: 9928873
    Abstract: An apparatus comprises a slider configured for writing data to and reading data from a magnetic recording medium and for heat-assisted magnetic recording. The slider comprises a heater configured to receive an AC signal and to cause oscillation in a spacing between the slider and the medium, and a contact sensor situated on the slider and configured to produce a DC response signal. A detector is coupled to the slider and configured to measure an amplitude of a spike in the DC response signal, calculate a ratio between the spike amplitude and an amplitude of the DC response signal, and detect contact between the slider and the medium in response to the ratio exceeding a predetermined threshold.
    Type: Grant
    Filed: June 30, 2017
    Date of Patent: March 27, 2018
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Dongming Liu, Huazhou Lou, Eric John McCalla, James Robert Oscarson, Shawn S. Silewski
  • Patent number: 9792940
    Abstract: Using a high sample rate dPES, together with pulsed heater and lock-in technique, to improve dPES SNR for contact detection between the head and media surface. Steps of powering a transducing head actuator with pulsed input signal at a select data track offset from a previously-written to data track of the storage medium, where the pulsed input signal has select amplitude and duty cycle to simulate a response signal, and further locking in an amplitude with respect to the heater frequency, can lead to a determination of level of heater power for initiating contact between the transducing head and the storage medium.
    Type: Grant
    Filed: March 15, 2013
    Date of Patent: October 17, 2017
    Assignee: Seagate Technology LLC
    Inventors: Lin Zhou, Juil Lee, Dongming Liu, Huazhou Lou
  • Patent number: 9548072
    Abstract: An apparatus comprises a heat-assisted magnetic recording (HAMR) head, a sensor, and a controller. The HAMR head is configured to interact with a magnetic storage medium. The sensor is configured to produce a signal indicating the occurrence of head-medium contact. The controller is configured to receive the signal and concurrently determine from the signal if the occurrence of head-medium contact is caused by a first contact detection parameter, a second contact detection parameter, or both the first and second contact detection parameters.
    Type: Grant
    Filed: February 11, 2015
    Date of Patent: January 17, 2017
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Huazhou Lou, Jason Riddering, Shawn S. Silewski, Dongming Liu, Lin Zhou
  • Publication number: 20160232931
    Abstract: An apparatus comprises a heat-assisted magnetic recording (HAMR) head, a sensor, and a controller. The HAMR head is configured to interact with a magnetic storage medium. The sensor is configured to produce a signal indicating the occurrence of head-medium contact. The controller is configured to receive the signal and concurrently determine from the signal if the occurrence of head-medium contact is caused by a first contact detection parameter, a second contact detection parameter, or both the first and second contact detection parameters.
    Type: Application
    Filed: February 11, 2015
    Publication date: August 11, 2016
    Inventors: Huazhou Lou, Jason Riddering, Shawn S. Silewski, Dongming Liu, Lin Zhou
  • Patent number: 9390741
    Abstract: A head transducer, configured to interact with a magnetic recording medium, includes a first sensor having a temperature coefficient of resistance (TCR) and configured to produce a first sensor signal, and a second sensor having a TCR and configured to produce a second sensor signal. One of the first and second sensors is situated at or near a close point of the head transducer in relation to the magnetic recording medium, and the other of the first and second sensors spaced away from the close point. Circuitry is configured to combine the first and second sensor signals and produce a combined sensor signal indicative of one or both of a change in head-medium spacing and head-medium contact. Each of the sensors may have a TCR with the same sign (positive or negative) or each sensor may have a TCR with a different sign.
    Type: Grant
    Filed: May 22, 2015
    Date of Patent: July 12, 2016
    Assignee: SAEGATE TECHNOLOGY LLC
    Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
  • Patent number: 9202495
    Abstract: A method and apparatus are provided for positioning a transducer relative to a track of a data storage medium and inducing lateral modulation of transducer the relative to the track. An element of the transducer is actuated toward the storage medium during the lateral modulation, and atomic interaction is detected between the element and the storage medium because of a change in a response to the lateral modulation of the transducer due to the atomic interaction.
    Type: Grant
    Filed: May 1, 2007
    Date of Patent: December 1, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Dongming Liu, Lin Zhou, Lance E. Stover
  • Patent number: 9135938
    Abstract: A method of detecting a contact between a transducing head and a storage medium is provided. The method applies an input signal, having a select power level and known frequency, to an actuator for actuating the head. An output signal is obtained in response to the input signal. At least one signal component is extracted from the output signal at the same or a harmonic of the same known frequency as the input signal applied to the actuator. Whether the at least one extracted signal component indicates a contact between the head and the medium is determined. The power level of the applied wave pattern is increased incrementally until the extracted signal component indicates a contact between the head and the storage medium.
    Type: Grant
    Filed: May 20, 2014
    Date of Patent: September 15, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Dongming Liu, Lin Zhou, Adam Karl Himes, Lee Clifford Knippenberg, Michael Thomas Johnson
  • Publication number: 20150255102
    Abstract: A head transducer, configured to interact with a magnetic recording medium, includes a first sensor having a temperature coefficient of resistance (TCR) and configured to produce a first sensor signal, and a second sensor having a TCR and configured to produce a second sensor signal. One of the first and second sensors is situated at or near a close point of the head transducer in relation to the magnetic recording medium, and the other of the first and second sensors spaced away from the close point. Circuitry is configured to combine the first and second sensor signals and produce a combined sensor signal indicative of one or both of a change in head-medium spacing and head-medium contact. Each of the sensors may have a TCR with the same sign (positive or negative) or each sensor may have a TCR with a different sign.
    Type: Application
    Filed: May 22, 2015
    Publication date: September 10, 2015
    Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
  • Patent number: 9082440
    Abstract: A bias signal is applied to a resistive thermal sensor located proximate a magnetic media reading surface of a magnetic sensor. The bias signal is modulated between first and second bias levels. First and second resistances of the resistive thermal sensor corresponding to the first and second bias levels are measured. Based a difference between the first and second resistances caused by in increase in thermal conductivity between the magnetic sensor and a medium as the magnetic head gets closer to the medium, at least one of a spacing and a contact between the magnetic sensor and the medium are determined.
    Type: Grant
    Filed: July 23, 2012
    Date of Patent: July 14, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Michael Thomas Johnson, Manuel Charles Anaya Dufresne, Xuan Zheng, Dongming Liu
  • Patent number: 9047898
    Abstract: An apparatus includes a head transducer configured to interact with a magnetic recording medium and a heater configured to thermally actuate the head transducer. A thermal sensor at or near the head transducer is configured to produce a sensor signal. Circuitry is coupled to the heater and configured to cause an oscillation in heater power. The heater power oscillation causes an oscillation in the sensor signal. A detector is coupled to the thermal sensor and configured to detect head-medium contact using the oscillating sensor signal and heater power.
    Type: Grant
    Filed: January 28, 2014
    Date of Patent: June 2, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Dongming Liu, Kenneth Haapala, Scott E. Ryun, Lin Zhou
  • Patent number: 9042050
    Abstract: A head transducer, configured to interact with a magnetic recording medium, includes a first sensor having a temperature coefficient of resistance (TCR) and configured to produce a first sensor signal, and a second sensor having a TCR and configured to produce a second sensor signal. One of the first and second sensors is situated at or near a close point of the head transducer in relation to the magnetic recording medium, and the other of the first and second sensors spaced away from the close point. Circuitry is configured to combine the first and second sensor signals and produce a combined sensor signal indicative of one or both of a change in head-medium spacing and head-medium contact. Each of the sensors may have a TCR with the same sign (positive or negative) or each sensor may have a TCR with a different sign.
    Type: Grant
    Filed: August 12, 2014
    Date of Patent: May 26, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
  • Patent number: 9036290
    Abstract: A head transducer, configured to interact with a magnetic recording medium, includes a first sensor having a temperature coefficient of resistance (TCR) and configured to produce a first sensor signal, and a second sensor having a TCR and configured to produce a second sensor signal. One of the first and second sensors is situated at or near a close point of the head transducer in relation to the magnetic recording medium, and the other of the first and second sensors spaced away from the close point. Circuitry is configured to combine the first and second sensor signals and produce a combined sensor signal indicative of one or both of a change in head-medium spacing and head-medium contact. Each of the sensors may have a TCR with the same sign (positive or negative) or each sensor may have a TCR with a different sign.
    Type: Grant
    Filed: August 12, 2014
    Date of Patent: May 19, 2015
    Assignee: SEAGATE TECHNOLOGY LLC
    Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
  • Publication number: 20140355150
    Abstract: A head transducer, configured to interact with a magnetic recording medium, includes a first sensor having a temperature coefficient of resistance (TCR) and configured to produce a first sensor signal, and a second sensor having a TCR and configured to produce a second sensor signal. One of the first and second sensors is situated at or near a close point of the head transducer in relation to the magnetic recording medium, and the other of the first and second sensors spaced away from the close point. Circuitry is configured to combine the first and second sensor signals and produce a combined sensor signal indicative of one or both of a change in head-medium spacing and head-medium contact. Each of the sensors may have a TCR with the same sign (positive or negative) or each sensor may have a TCR with a different sign.
    Type: Application
    Filed: August 12, 2014
    Publication date: December 4, 2014
    Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
  • Publication number: 20140347760
    Abstract: A head transducer, configured to interact with a magnetic recording medium, includes a first sensor having a temperature coefficient of resistance (TCR) and configured to produce a first sensor signal, and a second sensor having a TCR and configured to produce a second sensor signal. One of the first and second sensors is situated at or near a close point of the head transducer in relation to the magnetic recording medium, and the other of the first and second sensors spaced away from the close point. Circuitry is configured to combine the first and second sensor signals and produce a combined sensor signal indicative of one or both of a change in head-medium spacing and head-medium contact. Each of the sensors may have a TCR with the same sign (positive or negative) or each sensor may have a TCR with a different sign.
    Type: Application
    Filed: August 12, 2014
    Publication date: November 27, 2014
    Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
  • Publication number: 20140269241
    Abstract: Using a high sample rate dPES, together with pulsed heater and lock-in technique, to improve dPES SNR for contact detection between the head and media surface. Steps of powering a transducing head actuator with pulsed input signal at a select data track offset from a previously-written to data track of the storage medium, where the pulsed input signal has select amplitude and duty cycle to simulate a response signal, and further locking in an amplitude with respect to the heater frequency, can lead to a determination of level of heater power for initiating contact between the transducing head and the storage medium.
    Type: Application
    Filed: March 15, 2013
    Publication date: September 18, 2014
    Inventors: Lin Zhou, Juil Lee, Dongming Liu, Huazhou Lou
  • Publication number: 20140254344
    Abstract: A method of detecting a contact between a transducing head and a storage medium is provided. The method applies an input signal, having a select power level and known frequency, to an actuator for actuating the head. An output signal is obtained in response to the input signal. At least one signal component is extracted from the output signal at the same or a harmonic of the same known frequency as the input signal applied to the actuator. Whether the at least one extracted signal component indicates a contact between the head and the medium is determined. The power level of the applied wave pattern is increased incrementally until the extracted signal component indicates a contact between the head and the storage medium.
    Type: Application
    Filed: May 20, 2014
    Publication date: September 11, 2014
    Applicant: Seagate Technology LLC
    Inventors: Dongming Liu, Lin Zhou, Adam Karl Himes, Lee Clifford Knippenberg, Michael Thomas Johnson
  • Publication number: 20140254040
    Abstract: An apparatus includes a head transducer configured to interact with a magnetic recording medium and a heater configured to thermally actuate the head transducer. A thermal sensor at or near the head transducer is configured to produce a sensor signal. Circuitry is coupled to the heater and configured to cause an oscillation in heater power. The heater power oscillation causes an oscillation in the sensor signal. A detector is coupled to the thermal sensor and configured to detect head-medium contact using the oscillating sensor signal and heater power.
    Type: Application
    Filed: January 28, 2014
    Publication date: September 11, 2014
    Applicant: Seagate Technology LLC
    Inventors: Dongming Liu, Kenneth Haapala, Scott E. Ryun, Lin Zhou
  • Patent number: 8810952
    Abstract: A head transducer, configured to interact with a magnetic recording medium, includes a first sensor having a temperature coefficient of resistance (TCR) and configured to produce a first sensor signal, and a second sensor having a TCR and configured to produce a second sensor signal. One of the first and second sensors is situated at or near a close point of the head transducer in relation to the magnetic recording medium, and the other of the first and second sensors spaced away from the close point. Circuitry is configured to combine the first and second sensor signals and produce a combined sensor signal indicative of one or both of a change in head-medium spacing and head-medium contact. Each of the sensors may have a TCR with the same sign (positive or negative) or each sensor may have a TCR with a different sign.
    Type: Grant
    Filed: November 17, 2011
    Date of Patent: August 19, 2014
    Assignee: Seagate Technology LLC
    Inventors: Michael T. Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy W. Stoebe, James G. Wessel, Xuan Zheng
  • Patent number: 8730611
    Abstract: A method of detecting a contact between a transducing head and a storage medium is provided. The method applies an input signal, having a select power level and known frequency, to an actuator for actuating the head. An output signal is obtained in response to the input signal. At least one signal component is extracted from the output signal at the same or a harmonic of the same known frequency as the input signal applied to the actuator. Whether the at least one extracted signal component indicates a contact between the head and the medium is determined. The power level of the applied wave pattern is increased incrementally until the extracted signal component indicates a contact between the head and the storage medium.
    Type: Grant
    Filed: February 28, 2011
    Date of Patent: May 20, 2014
    Assignee: Seagate Technology LLC
    Inventors: Dongming Liu, Lin Zhou, Adam K. Himes, Lee C. Knippenberg, Michael T. Johnson
  • Patent number: 8638349
    Abstract: An apparatus includes a head transducer configured to interact with a magnetic recording medium and a heater configured to thermally actuate the head transducer. A thermal sensor at or near the head transducer is configured to produce a sensor signal. Circuitry is coupled to the heater and configured to cause an oscillation in heater power. The heater power oscillation causes an oscillation in the sensor signal. A detector is coupled to the thermal sensor and configured to detect head-medium contact using the oscillating sensor signal and heater power.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: January 28, 2014
    Assignee: Seagate Technology LLC
    Inventors: Dongming Liu, Kenneth Haapala, Scott E. Ryun, Lin Zhou