# US 12,183,375 B1 · Magnetic disk device and method of controlling magnetic disk device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,183,375 B1 - Document ID: US12183375B1 - Status: Granted - Kind: B1 - Application number: 18/419,989 - Filed: 2024-01-23 - Granted: 2024-12-31 - Earliest claimed: 2023-08-21 - Assignees: Kabushiki Kaisha Toshiba; Toshiba Electronic Devices & Storage Corporation - Applicants: Kabushiki Kaisha Toshiba; Toshiba Electronic Devices & Storage Corporation - Inventors: Takayuki Kawabe; Takeyori Hara - Web page: https://patentgrep.com/patent/US12183375B1 ## CPC - G11B 5/59627: {Aligning for runout, eccentricity or offset compensation (G11B5/5534, G11B5/59677, G11B5/59688 take precedence)} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, and a controller including an offtrack write table, positioning the magnetic head, and registering an address at which data in a track is written and a positioning error of the magnetic head at the address for the track, in the offtrack write table. When writing data to a first sector, the controller corrects a positioning target position of the first sector, based on a positioning error of a second sector located on two tracks away in a radial direction from the first sector. ## Claims ### Claim 1 A magnetic disk device comprising: a magnetic disk; a magnetic head positioned in a track provided at a predetermined track pitch of the magnetic disk, writing data to the track, and reading data from the track; and a controller including an offtrack write table, positioning the magnetic head, and registering an address at which data in the track is written and a positioning error of the magnetic head at the address for the track, in the offtrack write table, wherein when writing data to a first sector, the controller corrects a positioning target position of the first sector, based on a positioning error of a second sector located in two tracks away in a radial direction from the first sector. ### Claim 2 (depends on 1) The magnetic disk device of claim 1, wherein when the second sector is in an unregistered state or data is written to the second sector before data written to a sector between the first sector and the second sector, the controller determines the second sector to be in an inactive state and sets a positioning error of the second sector to zero. ### Claim 3 (depends on 1) The magnetic disk device of claim 1, wherein the controller corrects a positioning target position of the first sector, based on a positioning error of a third sector located in two tracks inside from the first sector and a positioning error of a fourth sector located in two tracks outside from the first sector. ### Claim 4 (depends on 3) The magnetic disk device of claim 3, wherein the controller corrects the positioning target position of the first sector, based on a correction amount which is half of a value obtained by adding the positioning error of the fourth sector to the positioning error of the third sector. ### Claim 5 (depends on 4) The magnetic disk device of claim 4, wherein when the third sector is in an unregistered state or data is written to the third sector before data written to a sector between the first sector and the third sector, the controller determines the third sector to be in an inactive state and sets the positioning error of the third sector to zero, when the fourth sector is in an unregistered state or data is written to the fourth sector before data written to a sector between the first sector and the fourth sector, the controller determines the fourth sector to be in an inactive state and sets the positioning error of the fourth sector to zero, and when the third sector or the fourth sector is in an inactive state, the controller corrects the positioning target position of the first sector to be offset to a side of the third sector or the fourth sector which is determined to be in the inactive state rather than the positioning target position corrected based on the correction amount. ### Claim 6 (depends on 4) The magnetic disk device of claim 4, wherein with respect to a pair of sectors adjacent to the first sector in a circumferential direction orthogonal to the radial direction, the controller calculates an initial correction amount value which is half of a value obtained by adding a positioning error of a sector located in two tracks outside from the pair of sector to a positioning error of a sector located in two tracks inside from the pair of sectors, the controller calculates an auxiliary offset amount which is half of a value obtained by adding an initial correction amount value of one of the pair of sectors to an initial correction amount of the other of the pair of sectors, the controller calculates an optimum correction amount value which is half of a value obtained by adding the auxiliary offset amount to the correction amount, and the controller corrects the positioning target position of the first sector, based on the optimum correction amount value. ### Claim 7 (depends on 4) The magnetic disk device of claim 4, wherein the controller calculates an initial correction amount value which is half of a value obtained by adding a positioning error of a sector outside two tracks to a positioning error of a sector inside two tracks, for a predetermined number of sectors arranged in a first direction from the first sector and a predetermined number of sectors located in a second direction opposite to the first direction from the first sector, in a circumferential direction orthogonal to the radial direction, the controller calculates an optimum correction amount value by linear combination of the initial correction amount value in the predetermined number of sectors with the correction amount, and the controller corrects the positioning target position of the first sector, based on the optimum correction amount value. ### Claim 8 (depends on 3) The magnetic disk device of claim 3, wherein the controller calculates a threshold value for determining whether or not to stop a write operation to the first sector, based on the positioning error of the third sector and the positioning error of the fourth sector, and the controller corrects the positioning target position of the first sector, based on the threshold value. ### Claim 9 A method of controlling a magnetic disk device comprising a magnetic disk, a magnetic head positioned in a track provided at a predetermined track pitch of the magnetic disk to write data to the track and read data from the track, and an offtrack write table, the method comprising: positioning the magnetic head; registering an address at which data in the track is written and a positioning error of the magnetic head at the address for the track, in the offtrack write table; and when writing data to a first sector, correcting a positioning target position of the first sector, based on a positioning error of a second sector located in two tracks away in a radial direction from the first sector.