Patents by Inventor Junguo Xu
Junguo Xu 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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Publication number: 20230005503Abstract: Various apparatuses, systems, methods, and media are disclosed to provide a heat-assisted magnetic recording (HAMR) medium that has a magnesium (Mg) trapping layer that is configured to mitigate Mg migration in the HAMR medium so as to prevent near field transducer (NFT) damage caused by dissociated Mg reacting with a compound used in the NFT. In one example, the HAMR medium can include a substrate, a seed layer on the substrate and including MgO, a magnetic recording layer on the seed layer, and a Mg trapping layer on the substrate and configured to mitigate Mg migration from the seed layer to a surface of the HAMR medium above the magnetic recording layer.Type: ApplicationFiled: July 1, 2021Publication date: January 5, 2023Inventors: Takashi Iwanami, Kouji Matsuda, Junguo Xu, Kenji Tasaka, Hoan Cong Ho, Tomoko Seki, Paul Christopher Dorsey, Masayoshi Shimokoshi
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Patent number: 9355668Abstract: A hard-disk drive having a structurally efficient magnetic head slider utilizes a MAMR-based spin torque oscillator (STO) for head-disk contact detection and for flying height sensing. Contact detection and spacing estimation techniques consider the nominal temperature difference, and thus different criteria, between read and write operations.Type: GrantFiled: May 21, 2013Date of Patent: May 31, 2016Assignee: HGST Netherlands B.V.Inventors: Yasutaka Nishida, Masato Shiimoto, Hiroyuki Katada, Ikuya Tagawa, Junguo Xu
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Patent number: 9311945Abstract: Embodiments of the present invention generally relate to a MAMR head. The MAMR head includes an STO and an embedded contact sensor (ECS). The STO and the ECS are electrically connected in series and are connected to the same terminals. During operation, the current applied to the STO is controlled with respect to a change in resistance of the ECS.Type: GrantFiled: November 6, 2013Date of Patent: April 12, 2016Assignee: HGST NETHERLANDS B.V.Inventors: Kenichiro Takahashi, Junguo Xu, Jianhua Li, Masaru Furukawa
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Patent number: 9159348Abstract: A method for measuring the head-disk clearance between a slider and a disk includes measuring a first resistance with a first bias applied to an embedded contact sensor of the slider, measuring a second resistance with a second bias applied to the embedded contact sensor of the slider, and determining the head-disk clearance based at least in part on a difference between the first resistance and the second resistance. A system includes a disk drive, a slider comprising an embedded contact sensor, and circuitry to apply at least two bias voltages to the embedded contact sensor, measure at least two resistances of the embedded contact sensor based on the application of the at least two bias voltages, and to determine the head-disk clearance based at least in part on a difference between the at least two resistances.Type: GrantFiled: December 17, 2013Date of Patent: October 13, 2015Assignee: HGST NETHERLANDS B.V.Inventors: Jianhua Li, Junguo Xu, Toshiya Shiramatsu, Takehiro Sato
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Publication number: 20150170695Abstract: A method for measuring the head-disk clearance between a slider and a disk includes measuring a first resistance with a first bias applied to an embedded contact sensor of the slider, measuring a second resistance with a second bias applied to the embedded contact sensor of the slider, and determining the head-disk clearance based at least in part on a difference between the first resistance and the second resistance. A system includes a disk drive, a slider comprising an embedded contact sensor, and circuitry to apply at least two bias voltages to the embedded contact sensor, measure at least two resistances of the embedded contact sensor based on the application of the at least two bias voltages, and to determine the head-disk clearance based at least in part on a difference between the at least two resistances.Type: ApplicationFiled: December 17, 2013Publication date: June 18, 2015Applicant: HGST NETHERLANDS B.V.Inventors: Jianhua Li, Junguo Xu, Toshiya Shiramatsu, Takehiro Sato
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Patent number: 9053725Abstract: A hard disk drive electronic component processes a signal from a piezoelectric actuator to identify where on a disk the slider encounters a disk defect. The signal received from the piezoelectric actuator may be based on the mechanical propagation, through the suspension to the piezoelectric actuator, of an effect of slider contact with the protrusion. Further, an actuator may be commanded to systematically move the head slider across the writeable portion of the disk to map all the protrusions on the writeable portion of the disk.Type: GrantFiled: August 25, 2014Date of Patent: June 9, 2015Assignee: HGST Netherlands B.V.Inventors: Yuichiro Sano, Junguo Xu, Yuka Morimoto
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Publication number: 20150124353Abstract: Embodiments of the present invention generally relate to a MAMR head. The MAMR head includes an STO and an embedded contact sensor (ECS). The STO and the ECS are electrically connected in series and are connected to the same terminals. During operation, the current applied to the STO is controlled with respect to a change in resistance of the ECS.Type: ApplicationFiled: November 6, 2013Publication date: May 7, 2015Applicant: HGST NETHERLANDS B.V.Inventors: Kenichiro TAKAHASHI, Junguo XU, Jianhua LI, Masaru FURUKAWA
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Patent number: 9007724Abstract: Embodiments disclosed herein generally relate to the data storage field and hard disk drives (HDD) using microwave assisted magnetic recording (MAMR) technology. Aspects of the preferred embodiments are to prevent the breakdown of spin torque oscillators (STO) due to large amounts of current flowing through the STO during head/disk contact. A magnetic head slider is disposed above and spaced apart from a disk. A STO is formed on a section of the magnetic head slider. Two electrodes are coupled to the STO, and one electrode has a higher potential than the other electrode. A preamplifier is adapted to send a current through the two electrodes, resulting in the higher potential electrode protruding closer to the disk than the lower potential electrode. Current then flows from one electrode to the disk without flowing through the STO, and breakdown of the STO is prevented.Type: GrantFiled: June 12, 2014Date of Patent: April 14, 2015Assignee: HGST Netherlands B.V.Inventors: Masaru Furukawa, Junguo Xu, Masato Shiimoto, Jianhua Li
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Publication number: 20140347969Abstract: A hard-disk drive having a structurally efficient magnetic head slider utilizes a MAMR-based spin torque oscillator (STO) for head-disk contact detection and for flying height sensing. Contact detection and spacing estimation techniques consider the nominal temperature difference, and thus different criteria, between read and write operations.Type: ApplicationFiled: May 21, 2013Publication date: November 27, 2014Applicant: HGST Netherlands B.V.Inventors: Yasutaka Nishida, Masato Shiimoto, Hiroyuki Katada, Ikuya Tagawa, Junguo Xu
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Patent number: 8885274Abstract: A method, apparatus, and system are provided for implementing enhanced surface analysis test (SAT) function for microwave assisted magnetic recording (MAMR) hard disk drives (HDDs) using embedded contact sensor (ECS) and spin-torque oscillator (STO) signals. A preamplifier circuit receives the embedded contact sensor (ECS) and spin-torque oscillator (STO) signals and compares the received ECS and STO signals to identify magnetic disk media defects including bumps or thermal-asperity (TA) defects and pits or hole defects.Type: GrantFiled: October 18, 2013Date of Patent: November 11, 2014Assignee: HGST Netherlands B.V.Inventors: Masaru Furukawa, Junguo Xu, Jianhua Li, Makoto Satou, Kenichiro Takahashi
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Patent number: 8797693Abstract: A method, apparatus, and system are provided for preventing electrostatic discharge (ESD) in hard disk drives using spin-torque oscillator (STO) for microwave assisted magnetic recording (MAMR). A control circuit adjusts a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element. The control circuit maintains a potential difference of less than about 115 millivolts (mV) between the disk and the STO element.Type: GrantFiled: August 26, 2013Date of Patent: August 5, 2014Assignee: HGST Netherlands B.V.Inventors: Masaru Furukawa, Junguo Xu, Makoto Satou, Kenji Suzuki
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Publication number: 20140110606Abstract: A near-field optical defect inspection apparatus according to an aspect of this invention includes a motor, a slider, a slider-moving mechanism, a light source, and a light-collecting probe. The motor rotates an object to be inspected. The slider slides above the rotating object. The slider-moving mechanism supports the slider and moves it above the object rotated by the motor. The light source emits inspection light that irradiates the object rotated by the motor, the inspection light propagating through an internal region of the object to be inspected. The light-collecting probe has an opening, from which the probe collects near-field light due to a defect in the object irradiated with the inspection light. The opening, formed on a surface of the slider that is opposed to the object to be inspected, has a maximal diameter smaller than a wavelength of visible light.Type: ApplicationFiled: May 27, 2011Publication date: April 24, 2014Applicant: Hitachi, Ltd.Inventors: Masaru Furukawa, Junguo Xu
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Patent number: 8670116Abstract: A defect inspecting method is provided which comprises a pre-scan defect inspecting process including a pre-scan irradiating step for casting irradiation light onto the surface of a sample, a pre-scan detecting step for detecting the scattered lights, and a pre-scan defect information collecting step for obtaining information on preselected defects present on the sample surface on the basis of the scattered lights; a near-field defect inspecting process including a near-field irradiating step in which the distance between the sample surface and a near-field head is adjusted so that the sample surface is irradiated, a near-field detecting step for detecting near-field light response, and a near-field defect information collecting step for obtaining information on the preselected defects on the basis of the near-field light response; and a merging process for inspecting defects present on the sample surface by merging the pieces of information on the preselected defects.Type: GrantFiled: May 20, 2011Date of Patent: March 11, 2014Assignee: Hitachi High-Technologies CorporationInventors: Toshiyuki Nakao, Junguo Xu, Yuki Shimizu, Toshihiko Nakata, Toshifumi Honda, Yukihiro Shibata, Yuta Urano
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Patent number: 8553512Abstract: A magnetic head slider inspection device including a motor unit for revolving a disk medium, a slider unit provided with a reproducing head, which is levitated from a surface of the disk medium under force generated by the revolving disk medium, a magnetic field generator positioned at an opposite side of the disk medium with respect to the slider unit for generating a magnetic field substantially perpendicular to the disk medium surface, and a circuit unit for generating the magnetic field from the magnetic field generator, and measuring a resistance value of the reproducing head levitated from the disk medium surface.Type: GrantFiled: April 1, 2011Date of Patent: October 8, 2013Assignee: Hitachi, Ltd.Inventors: Masaru Furukawa, Yukio Kato, Junguo Xu
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Patent number: 8477455Abstract: A slider comprising a contact sensor element configured to respond to a change in resistance due to a change in temperature, and a shield structure. The shield structure comprises a lower thermal conductivity than the contact sensor element and a greater hardness than the contact sensor element.Type: GrantFiled: November 16, 2010Date of Patent: July 2, 2013Assignee: HGST Netherlands B.V.Inventors: Masaru Furukawa, Yuki Shimizu, Junguo Xu, Yohji Maruyama, Takayoshi Ohtsu, Toshiya Shiramatsu
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Publication number: 20130155400Abstract: A defect inspecting method is provided which comprises a pre-scan defect inspecting process including a pre-scan irradiating step for casting irradiation light onto the surface of a sample, a pre-scan detecting step for detecting the scattered lights, and a pre-scan defect information collecting step for obtaining information on preselected defects present on the sample surface on the basis of the scattered lights; a near-field defect inspecting process including a near-field irradiating step in which the distance between the sample surface and a near-field head is adjusted so that the sample surface is irradiated, a near-field detecting step for detecting near-field light response, and a near-field defect information collecting step for obtaining information on the preselected defects on the basis of the near-field light response; and a merging process for inspecting defects present on the sample surface by merging the pieces of information on the preselected defects.Type: ApplicationFiled: May 20, 2011Publication date: June 20, 2013Inventors: Toshiyuki Nakao, Junguo Xu, Yuki Shimizu, Toshihiko Nakata, Toshifumi Honda, Yukihiro Shibata, Yuta Urano
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Patent number: 8315016Abstract: Provided is a head slider that can heat a recording medium with a simple structure. In the head slider (10), a hole portion (14h) having an opening in a medium facing surface (10a) facing a disk-shaped recording medium (2) is formed, and a heating element (32) that is heated by being energized and a reflection portion (43) for reflecting heat radiated from the heating element (32) toward the disk-shaped recording medium (2) are disposed in the hole portion (14h).Type: GrantFiled: October 19, 2009Date of Patent: November 20, 2012Assignee: Hitachi, Ltd.Inventors: Masaru Furukawa, Junguo Xu
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Patent number: 8270116Abstract: A magnetic disk drive includes a magnetic recording medium and a magnetic head slider adapted to fly over a surface of a magnetic recording medium and read or write information. The magnetic head slider includes a slider air bearing surface and a magnetic transducer. The slider air bearing surface includes a front pad having front rail surfaces and front step bearing surfaces, a rear pad having a rear rail surface and a rear step bearing surface, and a negative-pressure groove interposed between the front pad and the rear pad. A vibration suppressing groove is formed in the rear rail surface so as to be deeper than the rear rail surface and to be closed at its periphery. The vibration suppressing groove quickly damps out translational and pitching vibrations in the flying height direction of the magnetic head slider while stabilizing its flying.Type: GrantFiled: September 14, 2006Date of Patent: September 18, 2012Assignee: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Yuki Shimizu, Junguo Xu, Jianhua Li, Takanori Yamazaki
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Patent number: 8218266Abstract: Embodiments of the present invention provide a slider that may suppress contamination from being attached to the flying surface of the slider without influence on reduction of the flying height of the slider. Ions exerting an effect of decreasing surface energy are implanted in the whole surface of a flying surface of a magnetic head slider except for a front rail surface and a center rail surface. According to this, contamination is prevented from being attached to a front step bearing surface, a side step bearing surface, a center step bearing surface and a negative pressure groove where contamination is particularly liable to be attached in the flying surface of the magnetic head slider, so as to suppress destabilization in flying of the slider.Type: GrantFiled: September 7, 2007Date of Patent: July 10, 2012Assignee: HGST Netherlands BVInventors: Yuki Shimizu, Junguo Xu, Jianhua Li, Hidekazu Kohira, Tetsuya Matsusaki, Hidetoshi Anan
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Patent number: 8184397Abstract: A hard-disk drive. The hard-disk drive includes a disk enclosure, a magnetic-recording disk accommodated in the disk enclosure, and a diffusion suppressing film. The diffusion suppressing film divides the space in the disk enclosure into a first space where the magnetic-recording disk is disposed and a second space for retaining a lubricant. The diffusion suppressing film also suppresses diffusion of the lubricant from the second space to the first space.Type: GrantFiled: December 9, 2009Date of Patent: May 22, 2012Assignee: Hitachi Global Storage Technologies, Netherlands B.V.Inventors: Yukio Kato, Junguo Xu, Nobuo Nakagawa