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1.发明公开公开(公告)号：US20230260543A1
公开(公告)日：2023-08-17
申请号：US18192386
申请日：2023-03-29
Applicant: FUJIFILM Corporation
Inventor： Takashi FUJIMOTO , Eiki OZAWA
CPC classification number: G11B5/70678 , G11B5/733 , G11B5/78
Abstract: Provided are: a magnetic recording medium including a non-magnetic support and a magnetic layer containing a ferromagnetic powder, in which the ferromagnetic powder is an ε-iron oxide powder, a vertical squareness ratio SQ of the magnetic recording medium is 0.50 or more and 0.95 or less at a measurement temperature of 25° C., and an inclination of SQ obtained from SQ at a measurement temperature of 10° C., SQ at a measurement temperature of 25° C., and SQ at a measurement temperature of 40° C. is −0.0050° C.−1 or more and −0.0003° C.−1 or less; a magnetic tape cartridge including the magnetic recording medium which is a magnetic tape; and a magnetic recording and reproducing device including the magnetic recording medium.
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公开(公告)号：US20210287711A1
公开(公告)日：2021-09-16
申请号：US17199669
申请日：2021-03-12
Applicant: FUJIFILM Corporation
Inventor： Takashi FUJIMOTO , Norihito KASADA , Eiki OZAWA
IPC: G11B5/706
Abstract: The magnetic tape includes a non-magnetic support and a magnetic layer including ferromagnetic powder, in which the ferromagnetic powder is ε-iron oxide powder, and a coefficient of variation of particle size of the ε-iron oxide powder in a longitudinal direction of the magnetic layer is 0.50% or more and 5.00% or less.
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3.发明申请公开(公告)号：US20210287703A1
公开(公告)日：2021-09-16
申请号：US17195954
申请日：2021-03-09
Applicant: FUJIFILM Corporation
Inventor： Eiki OZAWA , Norihito Kasada , Takashi Fujimoto
Abstract: The magnetic recording medium includes: a non-magnetic support; and a magnetic layer containing a ferromagnetic powder, in which the ferromagnetic powder is an ε-iron oxide powder, and a transition temperature Tc of the magnetic recording medium measured after pressing the magnetic layer at a pressure of 70 atm is 80° C. to 240° C.
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公开(公告)号：US20210090600A1
公开(公告)日：2021-03-25
申请号：US17022446
申请日：2020-09-16
Applicant: FUJIFILM Corporation
Inventor： Takuto KUROKAWA , Naoki SANO , Norihito KASADA , Eiki OZAWA , Megumi NAKANO
Abstract: The magnetic recording medium includes a non-magnetic support; a magnetic layer that includes ferromagnetic powder on one surface side of the non-magnetic support; and a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support, in which a difference between a spacing measured on a surface of the back coating layer by optical interferometry under a pressure of 0.5 atm after n-hexane cleaning and a spacing measured on the surface of the back coating layer by optical interferometry under a pressure of 13.5 atm after n-hexane cleaning is 3 nm or less.
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公开(公告)号：US20200005820A1
公开(公告)日：2020-01-02
申请号：US16456965
申请日：2019-06-28
Applicant: FUJIFILM Corporation
Inventor： Eiki OZAWA , Norihito KASADA , Atsushi MUSHA
Abstract: A magnetic tape apparatus, in which a tilt cos θ of the hexagonal ferrite powder with respect to a surface of the magnetic layer acquired by cross section observation by STEM is 0.85 to 1.00, a reading element unit includes a plurality of reading elements each of which reads data by a linear scanning method from a specific track region including a reading target track in a track region included in the magnetic tape, an extraction unit performs a waveform equalization process according to a deviation amount between positions of the magnetic tape and the reading element unit, with respect to each reading result for each reading element, to extract data derived from the reading target track from the reading result, and the deviation amount is determined in accordance with a result obtained by reading of the servo pattern included in the magnetic layer by a servo element.
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Patent Agency Ranking
公开(公告)号：US20190130936A1
公开(公告)日：2019-05-02
申请号：US16232165
申请日：2018-12-26
Applicant: FUJIFILM Corporation
Inventor： Tetsuya KANEKO , Norihito KASADA , Eiki OZAWA
CPC classification number: G11B5/3909 , G11B5/00826 , G11B5/5526 , G11B5/584 , G11B5/5926 , G11B5/59633 , G11B5/59688 , G11B5/66 , G11B5/70
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.
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公开(公告)号：US20180286452A1
公开(公告)日：2018-10-04
申请号：US15920635
申请日：2018-03-14
Applicant: FUJIFILM Corporation
Inventor： Eiki OZAWA , Norihito KASADA
CPC classification number: G11B5/714 , G11B5/00813 , G11B5/3909 , G11B5/584 , G11B5/70 , G11B5/70615
Abstract: The magnetic tape device includes a TMR head and a magnetic tape, in which the magnetic tape includes fatty acid ester in a magnetic layer, Ra measured regarding a surface of the magnetic layer is 2.0 nm or smaller, full widths at half maximum of spacing distribution measured by optical interferometry regarding a surface of the magnetic layer before and after performing a vacuum heating with respect to the magnetic tape are greater than 0 nm and 7.0 nm or smaller, a difference between spacings before and after the vacuum heating is greater than 0 nm and 8.0 nm or smaller, and a ratio of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster thereof in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.
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公开(公告)号：US20180286450A1
公开(公告)日：2018-10-04
申请号：US15920544
申请日：2018-03-14
Applicant: FUJIFILM Corporation
Inventor： Norihito KASADA , Eiki OZAWA
CPC classification number: G11B5/714 , G11B5/00813 , G11B5/3909 , G11B5/70 , G11B5/70615 , G11B5/70678 , G11B5/82
Abstract: The magnetic tape device includes a magnetic tape including a magnetic layer; and a TMR head (reproducing head), 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 %.
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公开(公告)号：US20180240481A1
公开(公告)日：2018-08-23
申请号：US15899430
申请日：2018-02-20
Applicant: FUJIFILM Corporation
Inventor： Norihito KASADA , Eiki OZAWA
CPC classification number: G11B5/584 , G11B5/00813 , G11B5/3909 , G11B5/70 , G11B5/70678 , G11B5/78
Abstract: The magnetic tape device includes a TMR head as a servo head; and a magnetic tape which includes a magnetic layer including ferromagnetic hexagonal ferrite powder and a binding agent, and including a servo pattern, an XRD intensity ratio (Int(110)/Int(114)) 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, and a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050.
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公开(公告)号：US20180240479A1
公开(公告)日：2018-08-23
申请号：US15900144
申请日：2018-02-20
Applicant: FUJIFILM Corporation
Inventor： Norihito KASADA , Eiki OZAWA
CPC classification number: G11B5/3909 , G11B5/00813 , G11B5/00817 , G11B5/21 , G11B5/70 , G11B5/78
Abstract: The magnetic tape device includes a magnetic tape; and a TMR head as a reproducing head, in which a center line average surface roughness Ra measured regarding a surface of the magnetic layer of the magnetic tape is equal to or smaller than 2.0 nm, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, and ΔSFD in a longitudinal direction of the magnetic tape calculated by Expression 1: ΔSFD=SFD25° C.−SFD−190° C. is equal to or smaller than 0.50, wherein, in Expression 1, the SFD25° C. is a switching field distribution SFD measured in a longitudinal direction of the magnetic tape at a temperature of 25° C., and the SFD−190° C. is a switching field distribution SFD measured in a longitudinal direction of the magnetic tape at a temperature of −190° C.
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