Patents by Inventor Toshio HIROI

Toshio HIROI has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 10255938
    Abstract: A magnetic recording medium of the present invention includes a non-magnetic substrate, and a magnetic layer containing a magnetic powder. The magnetic powder is constituted by an ?-iron oxide powder. The magnetic layer has a squareness in a thickness direction of 0.65 or more. In a differential curve obtained by differentiating a hysteresis curve in the thickness direction of the magnetic layer, two or more peaks are present. In a case where, out of peaks in the same direction among the above-described peaks, a local maximum of a largest peak in a magnetic field range of +500 oersted [Oe] or more is taken as P1 and a local maximum of a largest peak in a magnetic field range of ?500 oersted [Oe] or more and less than +500 oersted [Oe] is taken as P2, a relationship below is satisfied: 0.25?P2/P1?0.60.
    Type: Grant
    Filed: January 31, 2017
    Date of Patent: April 9, 2019
    Assignee: MAXELL HOLDINGS, LTD.
    Inventors: Toshio Hiroi, Shinji Kawakami, Kenji Tanaka
  • Publication number: 20180182422
    Abstract: In a magnetic recording medium according to the present invention, if a straight line W having a length of 500 nm and a width of 15 nm is displayed parallel to a width direction of the magnetic layer and a straight line L having a length of 500 nm and a width of 15 nm is displayed parallel to a longitudinal direction of the magnetic layer, the number of magnetic particles that intersect the straight line W is N1, and the number of magnetic particles that intersect the straight line L is N2, then, a relationship of N1/0.5>60 and N2/0.5>60 is established where N1/0.5 is the number of magnetic particles per micrometer obtained by dividing N1 by 0.5 ?m and N2/0.5 is the number of magnetic particles per micrometer obtained by dividing N2 by 0.5 ?m.
    Type: Application
    Filed: December 27, 2017
    Publication date: June 28, 2018
    Applicant: Maxell Holdings, Ltd.
    Inventors: Shinji KAWAKAMI, Toshio HIROI, Masao FUJITA
  • Publication number: 20170221513
    Abstract: A magnetic recording medium of the present invention includes a non-magnetic substrate, and a magnetic layer containing a magnetic powder. The magnetic powder is constituted by an ?-iron oxide powder. The magnetic layer has a squareness in a thickness direction of 0.65 or more. In a differential curve obtained by differentiating a hysteresis curve in the thickness direction of the magnetic layer, two or more peaks are present. In a case where, out of peaks in the same direction among the above-described peaks, a local maximum of a largest peak in a magnetic field range of +500 oersted [Oe] or more is taken as P1 and a local maximum of a largest peak in a magnetic field range of ?500 oersted [Oe] or more and less than +500 oersted [Oe] is taken as P2, a relationship below is satisfied: 0.25?P2/P1?0.60.
    Type: Application
    Filed: January 31, 2017
    Publication date: August 3, 2017
    Applicant: HITACHI MAXELL, LTD.
    Inventors: Toshio HIROI, Shinji KAWAKAMI, Kenji TANAKA