Patents by Inventor Kei Yasuna
Kei Yasuna 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).
-
Publication number: 20230402062Abstract: Various illustrative aspects are directed to a data storage device, comprising: one or more disks; an actuating mechanism comprising one or more heads, and configured to position the one or more heads proximate to disk surfaces of the one or more disks; and one or more processing devices. The one or more processing devices are configured to: determine a first burst value based on an averaged value of a first set of one or more bursts; determine a second burst value based on an averaged value of a second set of one or more bursts; generate a position error signal (PES) based on the determined first burst value and the determined second burst value; and control a position of at least one head among the one or more heads based on the PES.Type: ApplicationFiled: June 13, 2022Publication date: December 14, 2023Inventors: Kei Yasuna, Guoxiao Guo, Ichiro Yokokawa
-
Patent number: 11830524Abstract: Various illustrative aspects are directed to a data storage device, comprising: one or more disks; an actuating mechanism comprising one or more heads, and configured to position the one or more heads proximate to disk surfaces of the one or more disks; and one or more processing devices. The one or more processing devices are configured to: determine a first burst value based on an averaged value of a first set of one or more bursts; determine a second burst value based on an averaged value of a second set of one or more bursts; generate a position error signal (PES) based on the determined first burst value and the determined second burst value; and control a position of at least one head among the one or more heads based on the PES.Type: GrantFiled: June 13, 2022Date of Patent: November 28, 2023Assignee: WESTERN DIGITAL TECHNOLOGIES, INCInventors: Kei Yasuna, Guoxiao Guo, Ichiro Yokokawa
-
Patent number: 11587586Abstract: Various illustrative aspects are directed to a data storage device, comprising: one or more disks; an actuator assembly comprising a head, and configured to position the head over a corresponding disk surfaces; and one or more processing devices, wherein the head comprises: a write element; a laser unit; and a fly height control element, and wherein the one or more processing devices are configured to: iteratively perform write start operations of write start patterns with the head on the corresponding disk surface, at a plurality of values of at least one of laser pre-bias current, and write backoff; detect pattern signal amplitudes of the write start patterns on the corresponding disk surface; and determine a relation of write backoff to laser pre-bias current for the head, based at least in part on the pattern signal amplitudes.Type: GrantFiled: February 15, 2022Date of Patent: February 21, 2023Assignee: Western Digital Technologies, Inc.Inventors: Kei Yasuna, Guoxiao Guo, Masaru Furukawa, Shaomin Xiong, Duc H. Banh
-
Patent number: 11587587Abstract: Various illustrative aspects are directed to a data storage device, comprising: one or more disks; an actuator assembly comprising a head, and configured to position the head over a corresponding disk surface; and one or more processing devices, the head comprising: a write element; a laser unit; and a fly height control element, and wherein the one or more processing devices are configured to: iteratively perform spiral write operations of spiral patterns comprising a plurality of sync marks with the head on the corresponding disk surface, wherein the spiral write operations are performed at: a plurality of values of laser pre-bias current, write backoff, and/or start disk phase; detect pattern signal amplitudes of the spiral patterns on the corresponding disk surface; and determine a relation of write backoff to laser pre-bias current for the head, based on the pattern signal amplitudes of the spiral patterns.Type: GrantFiled: February 23, 2022Date of Patent: February 21, 2023Assignee: Western Digital Technologies, Inc.Inventors: Kei Yasuna, Guoxiao Guo, Masaru Furukawa, Shaomin Xiong, Duc H. Banh
-
Patent number: 10923146Abstract: A data storage device is disclosed comprising a head actuated over a disk. The head is used to read servo information from the disk and generate a position error signal (PES) representing a position of the head over the disk. A control signal is generated based on the PES and a triangle-shape dither signal, and the head is positioned over the disk using the control signal.Type: GrantFiled: June 5, 2020Date of Patent: February 16, 2021Assignee: Western Digital Technologies, Inc.Inventors: Guoxiao Guo, Edgar D. Sheh, Kei Yasuna, Due H. Banh
-
Patent number: 8873183Abstract: A system and method of writing servo write tracks to a rotating disk using a head having a read/write offset is disclosed. One embodiment utilizes a write element on the head to write the servo write tracks. A read element on the head is then positioned over the servo write tracks. The phase of a specific frequency component of the track shape error in the servo write track is measured during the positioning of the read element over the servo write track. A sine wave having a specific frequency and a phase is selected based on the measurement results. The sine wave is then applied to a servo system as a correction signal. A new servo write track is then written with the write element.Type: GrantFiled: December 8, 2010Date of Patent: October 28, 2014Assignee: HGST Netherlands B.V.Inventors: Kei Yasuna, Tomoo Ozaki, Makoto Takase, Takao Horiguchi
-
Patent number: 8743496Abstract: Embodiments described herein provide for robust servo patterns that comply with planarization constraints and also allow use of a single master template for manufacture of both the front and back of a magnetic disk. Planarization constraints are met because only a portion of servo data is hard patterned on the magnetic disk and the hard patterned servo data areas comply with planarization constraints. The servo pattern has two symmetrical servo write assist patterns, one on each side of a central burst pattern. The servo sync, SAM, track-ID, sector-ID, and/or RRO values can be written magnetically by the write head onto these servo write assist patterns after the completion of the planarization process. The symmetric design of the servo pattern allows both a left-to-right and a right-to-left servo write and read back, thereby enabling use of a single master template in magnetic disk manufacture.Type: GrantFiled: July 6, 2011Date of Patent: June 3, 2014Assignee: HGST Netherlands B.V.Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Patent number: 8670207Abstract: Embodiments described herein provide for robust servo patterns that comply with planarization constraints and also allow use of a single master template for manufacture of both the front and back of a magnetic disk. Planarization constraints are met because only a portion of servo data is hard patterned on the magnetic disk and the hard patterned servo data areas comply with planarization constraints. The servo pattern has two symmetrical servo write assist patterns, one on each side of a central burst pattern. The servo sync, SAM, track-ID, sector-ID, and/or RRO values can be written magnetically by the write head onto these servo write assist patterns after the completion of the planarization process. The symmetric design of the servo pattern allows both a left-to-right and a right-to-left servo write and read back, thereby enabling use of a single master template in magnetic disk manufacture.Type: GrantFiled: July 6, 2011Date of Patent: March 11, 2014Assignee: HGST Netherlands B.V.Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Patent number: 8630051Abstract: Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.Type: GrantFiled: July 6, 2011Date of Patent: January 14, 2014Assignee: HGST Netherlands B.V.Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Patent number: 8625219Abstract: Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.Type: GrantFiled: July 6, 2011Date of Patent: January 7, 2014Assignee: HGST Netherlands B.V.Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Patent number: 8619379Abstract: Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.Type: GrantFiled: July 6, 2011Date of Patent: December 31, 2013Assignee: HGST Netherlands B.V.Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Patent number: 8559126Abstract: A method for positioning a magnetic-recording head. The method includes correcting amplitude of each burst signal of a plurality of burst signals read out with the magnetic-recording head from each respective burst pattern of a plurality of burst patterns. In addition, the method includes computing a deviation of the magnetic-recording head from a track based on corrected amplitudes of the plurality of burst signals. Moreover, the method includes positioning the magnetic-recording head on the track based on the deviation of the magnetic-recording head.Type: GrantFiled: August 20, 2009Date of Patent: October 15, 2013Assignee: HGST Netherlands B.V.Inventors: Kei Yasuna, Minoru Hashimoto, Thambirajah Suthasun
-
Patent number: 8531794Abstract: Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.Type: GrantFiled: July 6, 2011Date of Patent: September 10, 2013Assignee: HGST Netherlands, B.V.Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Patent number: 8526132Abstract: Embodiments herein illustrate patterned servo data that allows the patterned disk to be planarized with a relatively simple planarization process. A magnetic disk, in this regard, includes a data region having a plurality of tracks. The magnetic disk also includes a plurality of servo bursts patterned in the magnetic disk at a plurality of locations in each track. The servo bursts are operable to direct a controller to center a write head over a track in the data region and write a track identification. The servo bursts include magnetic lands and nonmagnetic grooves. The magnetic lands of the servo burst are generally configured with a uniform polarity of magnetization and a first uniform width. The nonmagnetic grooves are configured with a second uniform width.Type: GrantFiled: February 3, 2010Date of Patent: September 3, 2013Assignee: HGST Netherlands, B.V.Inventors: Thomas R. Albrecht, Masahito Kobayashi, Keishi Takahashi, Kei Yasuna
-
Publication number: 20130010382Abstract: Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.Type: ApplicationFiled: July 6, 2011Publication date: January 10, 2013Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Publication number: 20130010384Abstract: Embodiments described herein provide for robust servo patterns that comply with planarization constraints and also allow use of a single master template for manufacture of both the front and back of a magnetic disk. Planarization constraints are met because only a portion of servo data is hard patterned on the magnetic disk and the hard patterned servo data areas comply with planarization constraints. The servo pattern has two symmetrical servo write assist patterns, one on each side of a central burst pattern. The servo sync, SAM, track-ID, sector-ID, and/or RRO values can be written magnetically by the write head onto these servo write assist patterns after the completion of the planarization process. The symmetric design of the servo pattern allows both a left-to-right and a right-to-left servo write and read back, thereby enabling use of a single master template in magnetic disk manufacture.Type: ApplicationFiled: July 6, 2011Publication date: January 10, 2013Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Publication number: 20130010385Abstract: Embodiments described herein provide for robust servo patterns that comply with planarization constraints and also allow use of a single master template for manufacture of both the front and back of a magnetic disk. Planarization constraints are met because only a portion of servo data is hard patterned on the magnetic disk and the hard patterned servo data areas comply with planarization constraints. The servo pattern has two symmetrical servo write assist patterns, one on each side of a central burst pattern. The servo sync, SAM, track-ID, sector-ID, and/or RRO values can be written magnetically by the write head onto these servo write assist patterns after the completion of the planarization process. The symmetric design of the servo pattern allows both a left-to-right and a right-to-left servo write and read back, thereby enabling use of a single master template in magnetic disk manufacture.Type: ApplicationFiled: July 6, 2011Publication date: January 10, 2013Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Publication number: 20130010388Abstract: Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.Type: ApplicationFiled: July 6, 2011Publication date: January 10, 2013Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Publication number: 20130010383Abstract: Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.Type: ApplicationFiled: July 6, 2011Publication date: January 10, 2013Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi
-
Publication number: 20130010389Abstract: Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.Type: ApplicationFiled: July 6, 2011Publication date: January 10, 2013Inventors: Keiichiro Nonaka, Kei Yasuna, Masahito Kobayashi