# US 10,373,639 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 10,373,639 B2 - Document ID: US10373639B2 - Status: Granted - Kind: B2 - Application number: 15/920,768 - Filed: 2018-03-14 - Published: 2018-10-04 - Granted: 2019-08-06 - Earliest claimed: 2017-03-29 - Assignees: FUJIFILM Corporation - Applicants: FUJIFILM Corporation - Inventors: Norihito Kasada; Eiki Ozawa - Web page: https://patentgrep.com/patent/US10373639B2 ## CPC - G11B 5/714: characterised by the dimension of the magnetic particles - G11B 5/00813: {magnetic tapes} - G11B 5/3909: {Arrangements using a magnetic tunnel junction} - G11B 5/584: for track following on tapes - G11B 5/70: on a base layer - G11B 5/70615: {containing Fe metal or alloys (G11B5/70621 takes precedence)} - G11B 5/71: characterised by the lubricant - 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 including a magnetic layer, in which an intensity ratio of a peak intensity of a diffraction peak of a (110) plane with respect to a peak intensity of a diffraction peak of a (114) plane of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical direction squareness ratio of the magnetic tape is 0.65 to 1.00, Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, and a C—H derived C concentration calculated from a C—H peak area ratio of C1s spectra obtained by X-ray photoelectron spectroscopic analysis performed on the surface of the magnetic layer at a photoelectron take-off angle of 10 degrees is 45 to 65 atom %. ## Claims ### Claim 1 A magnetic tape device comprising: a magnetic tape; and a servo head, wherein 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, the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, an intensity ratio Int(110)/Int(114) of a peak intensity Int(110) of a diffraction peak of a (110) plane with respect to a peak intensity Int(114) of a diffraction peak of a (114) plane of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical direction squareness ratio of the magnetic tape is 0.65 to 1.00, a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, the magnetic layer includes one or more components selected from the group consisting of fatty acid and fatty acid amide, and a C—H derived C concentration calculated from a C—H peak area ratio of C1s spectra obtained by X-ray photoelectron spectroscopic analysis performed on the surface of the magnetic layer at a photoelectron take-off angle of 10 degrees is 45 to 65 atom %. ### Claim 2 (depends on 1) The magnetic tape device according to claim 1, wherein the center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.2 nm to 2.0 nm. ### Claim 3 (depends on 1) The magnetic tape device according to claim 1, Wherein the vertical direction squareness ratio of the magnetic tape is 0.65 to 0.90. ### Claim 4 (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. ### Claim 5 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 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, the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, an intensity ratio Int(110)/Int(114) of a peak intensity Int(110) of a diffraction peak of a (110) plane with respect to a peak intensity Int(114) of a diffraction peak of a (114) plane of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical direction squareness ratio of the magnetic tape is 0.65 to 1.00, a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, the magnetic layer includes one or more components selected from the group consisting of fatty acid and fatty acid amide, and a C—H derived C concentration calculated from a C—H peak area ratio of C1s spectra obtained by X-ray photoelectron spectroscopic analysis performed on the surface of the magnetic layer at a photoelectron take-off angle of 10 degrees is 45 to 65 atom %. ### Claim 6 (depends on 5) The head tracking servo method according to claim 5, wherein the center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.2 nm to 2.0 nm. ### Claim 7 (depends on 5) The head tracking servo method according to claim 5, wherein the vertical direction squareness ratio of the magnetic tape is 0.65 to 0.90. ### Claim 8 (depends on 5) The head tracking servo method according to claim 5, 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.