公开(公告)号：US20210035604A1

公开(公告)日：2021-02-04

申请号：US16942940

申请日：2020-07-30

Applicant: FUJIFILM Corporation

Inventor： Takashi Fujimoto

IPC: G11B5/65 ,  G11B5/73 ,  G11B5/127

Abstract: The magnetic recording medium includes a non-magnetic support; and a magnetic layer including a ferromagnetic powder, in which an anisotropic magnetic field distribution is 1.20 or less, and the ferromagnetic powder is ε-iron oxide powder.

公开(公告)号：US12159657B2

公开(公告)日：2024-12-03

申请号：US18455273

申请日：2023-08-24

Applicant: FUJIFILM Corporation

Inventor： Eiki Ozawa ,  Takashi Fujimoto

IPC: G11B5/706 ,  G11B5/714 ,  G11B5/73 ,  G11B5/735 ,  G11B5/84

Abstract: Provided are a magnetic recording medium including a non-magnetic support, and a magnetic layer including a ferromagnetic powder. The ferromagnetic powder is an ε-iron oxide powder, and an intensity ratio (Int1/Int2) of diffraction intensities obtained by an X-ray diffraction analysis of the magnetic layer using an In-Plane method after the magnetic layer is pressed at a pressure of 70 atm is 1.0 or more and 6.5 or less, a magnetic tape cartridge and a magnetic recording and reproducing device each including the magnetic recording medium.

公开(公告)号：US12014759B2

公开(公告)日：2024-06-18

申请号：US18192386

申请日：2023-03-29

Applicant: FUJIFILM Corporation

Inventor： Takashi Fujimoto ,  Eiki Ozawa

IPC: G11B5/706 ,  G11B5/733 ,  G11B5/78

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.

公开(公告)号：US11842756B2

公开(公告)日：2023-12-12

申请号：US18188639

申请日：2023-03-23

Applicant: FUJIFILM Corporation

Inventor： Takashi Fujimoto ,  Eiki Ozawa

IPC: G11B5/706 ,  G11B5/78

CPC classification number: G11B5/70689 ,  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 magnetization amount Φm per unit area of the magnetic recording medium is 5 G·μm or more and 100 G·μm or less at a measurement temperature of 25° C., and an inclination of Φm obtained from Φm at a measurement temperature of 10° C., Φm at a measurement temperature of 25° C., and Φm at a measurement temperature of 40° C. is −0.20 G·μm/° C. or more and −0.03 G·μm/° C. 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.

公开(公告)号：US20230238026A1

公开(公告)日：2023-07-27

申请号：US18192049

申请日：2023-03-29

Applicant: FUJIFILM Corporation

Inventor： Eiki Ozawa ,  Takashi Fujimoto

IPC: G11B5/706 ,  G11B5/735 ,  G11B5/714

CPC classification number: G11B5/70642 ,  G11B5/7356 ,  G11B5/714

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, H0.2 of the magnetic recording medium is 5,000 Oe or more and 40,000 Oe or less at a measurement temperature of 25° C., and an inclination of H0.2 obtained from H0.2 at a measurement temperature of 10° C., H0.2 at a measurement temperature of 25° C., and H0.2 at a measurement temperature of 40° C. is −100 Oe/° C. or more and −5 Oe/° C. 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.

公开(公告)号：US11189406B2

公开(公告)日：2021-11-30

申请号：US15993797

申请日：2018-05-31

Applicant: FUJIFILM Corporation

Inventor： Takashi Fujimoto

IPC: H01F1/11 ,  G11B5/65 ,  G11B5/706

Abstract: Magnetic powder includes: an epsilon-phase iron oxide-based compound selected from ε-Fe2O3 or a compound represented by Formula (1). The magnetic powder has an average particle diameter of 8 nm to 25 nm, a ratio of Hc to Hc′ of from 0.6 to 1.0, and Hc′ satisfying Expression (II). Hc′ represents a magnetic field at which a value of Expression (I) becomes zero in a magnetic field-magnetization curve obtained by performing measurement at a maximum applied magnetic field of 359 kA/m, a temperature of 296 K, and a magnetic field sweeping speed of 1.994 kA/m/s. M represents magnetization and H represents applied magnetic field. Hc represents a magnetic field at which magnetization becomes zero in the magnetic field-magnetization curve. In Formula (1), A represents at least one metal element other than Fe, and a represents a number that satisfies a relationship of 0

公开(公告)号：US20210287710A1

公开(公告)日：2021-09-16

申请号：US17199578

申请日：2021-03-12

Applicant: FUJIFILM Corporation

Inventor： Takashi Fujimoto ,  Norihito Kasada ,  Eiki Ozawa

IPC: G11B5/706 ,  G11B5/008 ,  G11B5/735 ,  G11B5/714

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 aspect ratio of the ε-iron oxide powder in a longitudinal direction of the magnetic layer is 0.20% or more and 8.00% or less.