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).
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Patent number: 9135938Abstract: 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: GrantFiled: May 20, 2014Date of Patent: September 15, 2015Assignee: SEAGATE TECHNOLOGY LLCInventors: Dongming Liu, Lin Zhou, Adam Karl Himes, Lee Clifford Knippenberg, Michael Thomas Johnson
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Publication number: 20150255102Abstract: 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: ApplicationFiled: May 22, 2015Publication date: September 10, 2015Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
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Patent number: 9082440Abstract: 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: GrantFiled: July 23, 2012Date of Patent: July 14, 2015Assignee: SEAGATE TECHNOLOGY LLCInventors: Michael Thomas Johnson, Manuel Charles Anaya Dufresne, Xuan Zheng, Dongming Liu
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Patent number: 9047898Abstract: 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: GrantFiled: January 28, 2014Date of Patent: June 2, 2015Assignee: SEAGATE TECHNOLOGY LLCInventors: Dongming Liu, Kenneth Haapala, Scott E. Ryun, Lin Zhou
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Patent number: 9042050Abstract: 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: GrantFiled: August 12, 2014Date of Patent: May 26, 2015Assignee: SEAGATE TECHNOLOGY LLCInventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
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Patent number: 9036290Abstract: 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: GrantFiled: August 12, 2014Date of Patent: May 19, 2015Assignee: SEAGATE TECHNOLOGY LLCInventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
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Publication number: 20140355150Abstract: 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: ApplicationFiled: August 12, 2014Publication date: December 4, 2014Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
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Publication number: 20140347760Abstract: 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: ApplicationFiled: August 12, 2014Publication date: November 27, 2014Inventors: Michael Thomas Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy William Stoebe, James Gary Wessel, Xuan Zheng
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Publication number: 20140269241Abstract: 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: ApplicationFiled: March 15, 2013Publication date: September 18, 2014Inventors: Lin Zhou, Juil Lee, Dongming Liu, Huazhou Lou
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Publication number: 20140254344Abstract: 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: ApplicationFiled: May 20, 2014Publication date: September 11, 2014Applicant: Seagate Technology LLCInventors: Dongming Liu, Lin Zhou, Adam Karl Himes, Lee Clifford Knippenberg, Michael Thomas Johnson
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Publication number: 20140254040Abstract: 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: ApplicationFiled: January 28, 2014Publication date: September 11, 2014Applicant: Seagate Technology LLCInventors: Dongming Liu, Kenneth Haapala, Scott E. Ryun, Lin Zhou
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Patent number: 8810952Abstract: 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: GrantFiled: November 17, 2011Date of Patent: August 19, 2014Assignee: Seagate Technology LLCInventors: Michael T. Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy W. Stoebe, James G. Wessel, Xuan Zheng
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Patent number: 8730611Abstract: 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: GrantFiled: February 28, 2011Date of Patent: May 20, 2014Assignee: Seagate Technology LLCInventors: Dongming Liu, Lin Zhou, Adam K. Himes, Lee C. Knippenberg, Michael T. Johnson
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Patent number: 8638349Abstract: 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: GrantFiled: March 11, 2013Date of Patent: January 28, 2014Assignee: Seagate Technology LLCInventors: Dongming Liu, Kenneth Haapala, Scott E. Ryun, Lin Zhou
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Publication number: 20140023108Abstract: 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: ApplicationFiled: July 23, 2012Publication date: January 23, 2014Applicant: SEAGATE TECHNOLOGY LLCInventors: Michael Thomas Johnson, Manuel Charles Anaya Dufresne, Xuan Zheng, Dongming Liu
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Patent number: 8553350Abstract: A system that is capable of monitoring tribological data, such as friction, in a data storage device. In accordance with various embodiments, a magnetoresistive head is separated from a rotating data storage media by an air bearing and attached to a slider that is adjusted through deformation controlled by a heating element. A measurement circuit concurrently monitors friction from the head and power applied to the heating element to determine an MR head clearance. The measurement circuit includes at least a phase filter that eliminates off-phase friction from contributing to the determination of the MR head clearance.Type: GrantFiled: May 27, 2011Date of Patent: October 8, 2013Assignee: Seagate Technology LLCInventors: Lin Zhou, Huazhou Lou, Dongming Liu, Vincent Bernard Engelkes
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Publication number: 20120300335Abstract: A system that is capable of monitoring tribological data, such as friction, in a data storage device. In accordance with various embodiments, a magnetoresistive head is separated from a rotating data storage media by an air bearing and attached to a slider that is adjusted through deformation controlled by a heating element. A measurement circuit concurrently monitors friction from the head and power applied to the heating element to determine an MR head clearance. The measurement circuit includes at least a phase filter that eliminates off-phase friction from contributing to the determination of the MR head clearance.Type: ApplicationFiled: May 27, 2011Publication date: November 29, 2012Applicant: SEAGATE TECHNOLOGY LLCInventors: Lin Zhou, Huazhou Lou, Dongming Liu, Vincent Bernard Engelkes
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Publication number: 20120218659Abstract: 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: ApplicationFiled: February 28, 2011Publication date: August 30, 2012Applicant: SEAGATE TECHNOLOGY LLCInventors: Dongming Liu, Lin Zhou, Adam K. Himes, Lee C. Knippenberg, Michael T. Johnson
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Publication number: 20120120522Abstract: 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: ApplicationFiled: November 17, 2011Publication date: May 17, 2012Applicant: SEAGATE TECHNOLOGY LLCInventors: Michael T. Johnson, Dongming Liu, Huazhou Lou, Declan Macken, Timothy W. Stoebe, James G. Wessel, Xuan Zheng
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Publication number: 20080273260Abstract: 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: ApplicationFiled: May 1, 2007Publication date: November 6, 2008Applicant: Seagate Technology LLCInventors: Dongming Liu, Lin Zhou, Lance E. Stover