# US 10,319,401 B1 · Magnetic disk device and control method for 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 10,319,401 B1 - Document ID: US10319401B1 - Status: Granted - Kind: B1 - Application number: 16/124,819 - Filed: 2018-09-07 - Granted: 2019-06-11 - Earliest claimed: 2018-02-27 - Assignees: Kabushiki Kaisha Toshiba; Toshiba Electronics Devices & Storage Corporation - Applicants: Kabushiki Kaisha Toshiba; Toshiba Electronic Devices & Storage Corporation - Inventors: Hiroshi Oyabu - Web page: https://patentgrep.com/patent/US10319401B1 ## CPC - G11B 5/607: {using thermal means} - G11B 5/3133: {including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure (G11B5/3106 takes precedence)} - G11B 5/4826: {Mounting, aligning or attachment of the transducer head relative to the arm assembly, e.g. slider holding members, gimbals, adhesive (G11B5/484 takes precedence; details of head housings or structures G11B5/10, G11B5/127; adjustment relative to the record carrier G11B5/56)} - 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 A magnetic disk device according to an embodiment includes: a head slider; a magnetic head provided in the head slider; a heater provided in the head slider; and a controller that determines, in seek operation of the magnetic head, a preheat start scheduled position from a remaining seek distance at which a time required for preheating of the head slider can be secured, the controller starting the preheating from the preheat start scheduled position in a case where no bump exists in an area from the preheat start scheduled position to a seek target position, the controller changing a preheat start position to an arbitrary position in an area from the bump to the seek target position in a case where the bump exists in the area from the preheat start scheduled position to the seek target position. ## Claims ### Claim 1 A magnetic disk device comprising: a head slider; a magnetic head provided in the head slider; a heater provided in the head slider; and a controller that determines, in seek operation of the magnetic head, a preheat start scheduled position from a remaining seek distance at which a time required for preheating of the head slider can be secured, the controller starting the preheating from the preheat start scheduled position in a case where no bump exists in an area from the preheat start scheduled position to a seek target position, the controller changing a preheat start position to an arbitrary position in an area from the bump to the seek target position in a case where the bump exists in the area from the preheat start scheduled position to the seek target position. ### Claim 2 (depends on 1) The magnetic disk device according to claim 1, wherein the controller adds, as one of calculation conditions of reordering, a preheat time generated after finishing a seek time in the case where the bump exists. ### Claim 3 (depends on 2) The magnetic disk device according to claim 2, wherein the controller performs reordering so as to allocate, to a moving time of the magnetic head, a preheat time generated after finishing the seek time in the case where the bump exists. ### Claim 4 (depends on 1) The magnetic disk device according to claim 1, wherein the controller changes the time required for preheating in accordance with a relation between a flying height of the magnetic head and a bit error rate in data writing. ### Claim 5 (depends on 4) The magnetic disk device according to claim 4, wherein the controller shortens the time required for preheating in a case where specification of the bit error rate is moderate. ### Claim 6 (depends on 1) The magnetic disk device according to claim 1, wherein the controller sets, to a position before the seek target position, the preheat start position in the case where the bump exists. ### Claim 7 (depends on 1) The magnetic disk device according to claim 1, wherein the controller changes the preheat start position in accordance with a position of the bump. ### Claim 8 (depends on 7) The magnetic disk device according to claim 7, wherein the controller starts the preheating at a predetermined position after passing a position where the bump exists. ### Claim 9 (depends on 1) The magnetic disk device according to claim 1, wherein, even in the case where the bump exists in the area from the preheat start scheduled position to the seek target position, the controller determines whether to start the preheating from the preheat start scheduled position in accordance with a relation between a seek orbit of the magnetic head and a position of the bump. ### Claim 10 (depends on 9) The magnetic disk device according to claim 9, wherein the controller starts the preheating from the preheat start scheduled position in a case where the bump exists outside an area calculated from the seek orbit of the magnetic head. ### Claim 11 A control method for a magnetic disk device, the method comprising: determining, in seek operation of a magnetic head, a preheat start scheduled position from a remaining seek distance at which a time required for preheating of a head slider including the magnetic head can be secured; and starting the preheating from the preheat start scheduled position in a case where no bump exists in an area from the preheat start scheduled position to a seek target position, and changing a preheat start position to an arbitrary position in an area from the bump to the seek target position in a case where the bump exists in the area from the preheat start scheduled position to the seek target position. ### Claim 12 (depends on 11) The control method for a magnetic disk device according to claim 11, comprising adding, as one of calculation conditions of reordering, a preheat time generated after finishing a seek time in the case where the bump exists. ### Claim 13 (depends on 12) The control method for a magnetic disk device according to claim 12, comprising performing reordering so as to allocate, to a moving time of the magnetic head, a preheat time generated after finishing the seek time in the case where the bump exists. ### Claim 14 (depends on 11) The control method for a magnetic disk device according to claim 11, comprising changing the time required for preheating in accordance with a relation between a flying height of the magnetic head and a bit error rate in data writing. ### Claim 15 (depends on 14) The control method for a magnetic disk device according to claim 14, comprising shortening the time required for preheating in a case where specification of the bit error rate is moderate. ### Claim 16 (depends on 11) The control method for a magnetic disk device according to claim 11, comprising setting, to a position before the seek target position, the preheat start position in the case where the bump exists. ### Claim 17 (depends on 11) The control method for a magnetic disk device according to claim 11, comprising changing the preheat start position in accordance with a position of the bump. ### Claim 18 (depends on 17) The control method for a magnetic disk device according to claim 17, comprising starting the preheating at a predetermined position after passing a position where the bump exists. ### Claim 19 (depends on 11) The control method for a magnetic disk device according to claim 11, comprising determining whether to start the preheating from the preheat start scheduled position in accordance with a relation between a seek orbit of the magnetic head and a position of the bump even in the case where the bump exists in the area from the preheat start scheduled position to the seek target position. ### Claim 20 (depends on 19) The control method for a magnetic disk device according to claim 19, comprising starting the preheating from the preheat start scheduled position in a case where the bump exists outside an area calculated from the seek orbit of the magnetic head.