Patents by Inventor Wakatake Matsuda

Wakatake Matsuda 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).

  • Method of producing magnetic thin film
    Patent number: 4232071
    Abstract: A method of roducing .gamma.-Fe.sub.2 O.sub.3 magnetic disk medium of continuous thin film is provided, in which a deposition source is deposited on an opposed Al-alloy substrate by means of a reactive vacuum deposition technique and the deposited film is thermally treated so as to be the magnetic disk medium. As the deposition source, a ferroalloy containing about 1 to 10 at.% Ti and about 0.5 to 5 at.% Co is employed.
    Type: Grant
    Filed: June 29, 1977
    Date of Patent: November 4, 1980
    Assignees: Nippon Telegraph and Telephone Public Corporation, Fujitsu Limited
    Inventors: Akira Terada, Seizi Hattori, Yoshikazu Ishii, Akira Nohara, Nobuo Inagaki, Wakatake Matsuda, Susumu Kawakami
  • Magnetic recording medium and process for producing the same
    Patent number: 4215158
    Abstract: A thin film of ferrite for use as a magnetic recording medium includes up to ten atomic percent of Nb based on the total number of metallic atoms in the ferrite film. This thin film of ferrite further includes up to fifteen atomic percent of Cu in addition to the Nb. The inclusion of Nb improves the squareness ratio and the coercive force of the recording medium, and also enlarges the temperature range of reduction from .alpha. -Fe.sub.2 O.sub.3 to one of the ferrites, i.e. Fe.sub.3 O.sub.4. The inclusion of Cu lowers the reduction temperature below 300.degree. C. According to the invention, a magnetic recording medium exhibiting excellent required properties, such as a high coercive force and a high squareness ratio, can be produced by a reliable process.
    Type: Grant
    Filed: March 2, 1977
    Date of Patent: July 29, 1980
    Assignees: Fujitsu Limited, Nippon Telegraph and Telephone Public Corporation
    Inventors: Seizi Hattori, Takehiko Nakagawa, Kazuo Kobayashi, Koichi Makino, Wakatake Matsuda
  • Process for producing a magnetic recording medium
    Patent number: 4156037
    Abstract: A thin film of ferrite for use as a magnetic recording medium contain (a) Cu, (b) both Cu and Co, or (c) Cu, Co and Nb. The inclusion of Cu increases the temperature range for reduction from .alpha.-Fe.sub.2 O.sub.3 to one of the ferrites, i.e. Fe.sub.3 O.sub.4, and also lowers the above-mentioned reducting temperature. The addition of Co improves the magnetic properties of the ferrite. The simultaneous addition of Cu, Co and Nb provides .gamma.-Fe.sub.2 O.sub.3 with excellent magnetic properties, which are stable over wide temperature range for oxidizing the Fe.sub.3 O.sub.4 to the .gamma.-Fe.sub.2 O.sub.3.
    Type: Grant
    Filed: March 3, 1977
    Date of Patent: May 22, 1979
    Assignees: Fujitsu Limited, Nippon Telegraph & Telephone Public Corporation
    Inventors: Seizi Hattori, Takehiko Nakagawa, Kazuo Kobayashi, Koichi Makino, Wakatake Matsuda