# US 10,373,633 B2 · Magnetic tape device and head tracking servo method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,373,633 B2 - Document ID: US10373633B2 - Status: Granted - Kind: B2 - Application number: 15/854,438 - Filed: 2017-12-26 - Published: 2018-06-28 - Granted: 2019-08-06 - Earliest claimed: 2016-12-27 - Assignees: FUJIFILM Corporation - Applicants: FUJIFILM Corporation - Inventors: Tetsuya Kaneko; Norihito Kasada; Eiki Ozawa - Web page: https://patentgrep.com/patent/US10373633B2 ## CPC - G11B 5/3909: {Arrangements using a magnetic tunnel junction} - G11B 5/00826: {comprising a plurality of single poles or gaps or groups thereof operative at the same time} - G11B 5/5526: {Control therefor; circuits, track configurations or relative disposition of servo-information transducers and servo-information tracks for control thereof (G11B5/556 takes precedence)} - G11B 5/584: for track following on tapes - G11B 5/5926: {recorded in separate tracks, e.g. servo tracks} - G11B 5/59633: {Servo formatting (G11B5/59627, G11B5/59677, G11B5/59683, G11B5/59688 take precedence)} - G11B 5/59688: {Servo signal format patterns or signal processing thereof, e.g. dual, tri, quad, burst signal patterns} - G11B 5/70: on a base layer - 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 The magnetic tape device includes: a magnetic tape; and a servo head, in which a magnetic tape transportation speed of the magnetic tape device is equal to or lower than 18 m/sec, the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element, the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, the magnetic layer includes a servo pattern, and a coefficient of friction measured regarding a base portion of a surface of the magnetic layer is equal to or smaller than 0.30. ## Claims ### Claim 1 A magnetic tape device comprising: a magnetic tape; and a servo head, wherein a magnetic tape transportation speed of the magnetic tape device is equal to or lower than 18 m/sec, the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element, the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, the magnetic layer includes a servo pattern, and a coefficient of friction measured regarding a base portion of a surface of the magnetic layer is equal to or smaller than 0.30. ### Claim 2 (depends on 1) The magnetic tape device according to claim 1, wherein the coefficient of friction measured regarding the base portion of the surface of the magnetic layer is 0.20 to 0.30. ### Claim 3 (depends on 1) The magnetic tape device according to claim 1, wherein a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.8 nm. ### Claim 4 (depends on 3) The magnetic tape device according to claim 3, wherein the center line average surface roughness Ra is equal to or smaller than 2.5 nm. ### Claim 5 (depends on 1) The magnetic tape device according to claim 1, wherein the magnetic tape includes a non-magnetic layer including non-magnetic powder and a binding agent between the non-magnetic support and the magnetic layer, and a total thickness of the magnetic layer and the non-magnetic layer is equal to or smaller than 1.8 μm. ### Claim 6 (depends on 5) The magnetic tape device according to claim 5, wherein the total thickness of the magnetic layer and the non-magnetic layer is equal to or smaller than 1.1 μm. ### Claim 7 A head tracking servo method comprising: reading a servo pattern of a magnetic layer of a magnetic tape by a servo head in a magnetic tape device, wherein a magnetic tape transportation speed of the magnetic tape device is equal to or lower than 18 m/sec, the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element, the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, the magnetic layer includes the servo pattern, and a coefficient of friction measured regarding a base portion of a surface of the magnetic layer is equal to or smaller than 0.30. ### Claim 8 (depends on 7) The head tracking servo method according to claim 7, wherein the coefficient of friction measured regarding the base portion of the surface of the magnetic layer is 0.20 to 0.30. ### Claim 9 (depends on 7) The head tracking servo method according to claim 7, wherein a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.8 nm. ### Claim 10 (depends on 9) The head tracking servo method according to claim 9, wherein the center line average surface roughness Ra is equal to or smaller than 2.5 nm. ### Claim 11 (depends on 7) The head tracking servo method according to claim 7, wherein the magnetic tape includes a non-magnetic layer including non-magnetic powder and a binding agent between the non-magnetic support and the magnetic layer, and a total thickness of the magnetic layer and the non-magnetic layer is equal to or smaller than 1.8 μm. ### Claim 12 (depends on 11) The head tracking servo method according to claim 11, wherein the total thickness of the magnetic layer and the non-magnetic layer is equal to or smaller than 1.1 μm.