Patents by Inventor Shin-ichiro Dezawa
Shin-ichiro Dezawa 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).
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Patent number: 4581251Abstract: A process for preparing cobalt-modified ferromagnetic iron oxide by modifying ferromagnetic .gamma.-Fe.sub.2 O.sub.3 particles with cobalt, wherein prior to cobalt modification treatment, the ferromagnetic .gamma.-Fe.sub.2 O.sub.3 is heat treated at a temperature in the range of from about -200.degree. C. to +30.degree. C. of the critical temperature at which partial transition of .gamma.-Fe.sub.2 O.sub.3 into .alpha.-Fe.sub.2 O.sub.3 occurs and which reduces the saturation magnetization to 99% of the saturation magnetization measured before the heat treatment, and the atomic ratio of Fe.sup.++ /Fe.sup.+++ after the cobalt modification is 0.00 to 0.10.Type: GrantFiled: June 28, 1984Date of Patent: April 8, 1986Assignee: Fuji Photo Film Co., Ltd.Inventors: Shin-ichiro Dezawa, Hideaki Kosha, Tatsuji Kitamoto
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Patent number: 4569856Abstract: A method for preparing a magnetic recording medium is described, comprising (1) pre-dispersing ferromagnetic particles having an S.sub.BET specific surface area of 35 m.sup.2 /g or more and having an adjusted water content of 0.8 wt % or more with a binder, (2) adding an additional binder and a lubricating agent thereinto, mixing and dispersing them to prepare a diserpsion of a magnetic coating composition, and (3) coating the resulting dispersion of a magnetic coating composition on a non-magnetic support.Type: GrantFiled: March 8, 1985Date of Patent: February 11, 1986Assignee: Fuji Photo Film Co., Ltd.Inventors: Takahito Miyoshi, Kenichi Masuyama, Shin-ichiro Dezawa, Toshimitu Okutu, Norio Nasu, Nobuo Aoki, Masaaki Fujiyama
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Patent number: 4486496Abstract: A magnetic recording medium which comprises a non-magnetic support having thereon a magnetic layer containing plate-shaped magnetic particles which have axes of easy magnetization perpendicular to their respective plate planes dispersed in a binder, the magnetic particles each having a multiple magnetic domain structure and having a particle diameter equal to or longer than the recorded effective shortest wavelength.Type: GrantFiled: May 26, 1982Date of Patent: December 4, 1984Assignee: Fuji Photo Film Co., Ltd.Inventors: Shin-ichiro Dezawa, Goro Akashi, Tatsuji Kitamoto
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Patent number: 4442159Abstract: A magnetic recording medium which comprises a non-magnetic support having thereon two or more magnetic layers comprising magnetic particles in a binder. The magnetic layer(s) other than the topmost layer comprises needle-shaped magnetic particles. The topmost layer comprises plate-shaped magnetic particles which have axes of easy magnetization perpendicular to the individual plate planes and the plate planes are oriented substantially parallel to the surface of the magnetic layer.Type: GrantFiled: May 26, 1982Date of Patent: April 10, 1984Assignee: Fuji Photo Film Co., Ltd.Inventors: Shin-ichiro Dezawa, Goro Akashi, Tatsuji Kitamoto
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Patent number: 4153920Abstract: This invention relates to a magnetic recording medium comprising a ferromagnetic metal thin film as a magnetic recording layer on a non-magnetic flexible support, in which the surface roughness of the support is 0.10 .mu.m or less and the period of the surface roughness is v/10.sup.6 .mu.m or less where v represents a relative speed between a magnetic head and magnetic recording medium by .mu.m/sec. In the case of providing an undercoated layer between the magnetic recording layer and non-magnetic flexible support, the surface roughness of the undercoated layer is adjusted to 0.10 .mu.m or less and the period of the surface roughness is adjusted to v/10.sup.6 .mu.m or less.Type: GrantFiled: November 21, 1977Date of Patent: May 8, 1979Assignee: Fuji Photo Film Co., Ltd.Inventors: Ryuji Shirahata, Tatsuji Kitamoto, Masaaki Suzuki, Shin-ichiro Dezawa
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Patent number: 4125474Abstract: In a process for producing a ferromagnetic powder having a high coercive force which comprises adding an aqueous solution containing Co.sup.+2 ions, or both Co.sup.+2 ions and another cation(s), and an alkali solution to a suspension of a ferromagnetic iron oxide containing the metal(s) given by these ion(s), the improvement wherein said ferromagnetic iron oxide is treated with a reducing agent prior to the preparation of the suspension.Type: GrantFiled: August 2, 1976Date of Patent: November 14, 1978Assignee: Fuji Photo Film Co., Ltd.Inventors: Shin-Ichiro Dezawa, Koji Sasazawa, Tatsuji Kitamoto, Nobuo Yamazaki
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Patent number: 4097650Abstract: This invention relates to a magnetic recording medium comprising a ferromagnetic metal thin film as a magnetic recording layer on a non-magnetic flexible support, in which the surface roughness of the support is 0.10 .mu.m or less and the period of the surface roughness is v/10.sup.6 .mu.m or less where v represents a relative speed between a magnetic head and magnetic recording medium by .mu.m/sec. In the case of providing an undercoated layer between the magnetic recording layer and non-magnetic flexible support, the surface roughness of the undercoated layer is adjusted to 0.10 .mu.m or less and the period of the surface roughness is adjusted to v/10.sup.6 .mu.m or less.Type: GrantFiled: August 24, 1976Date of Patent: June 27, 1978Assignee: Fuji Photo Film Co., Ltd.Inventors: Ryuji Shirahata, Tatsuji Kitamoto, Masaaki Suzuki, Shin-ichiro Dezawa
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Patent number: 4089993Abstract: This invention relates to a method of forming a metallic thin film on a plastic substrate by electroless plating, which comprises providing an undercoated layer consisting essentially of polyvinylidene chloride or vinylidene chloride copolymer on the surface of the plastic substrate and then subjecting to a surface activating treatment and electroless plating.Type: GrantFiled: October 19, 1976Date of Patent: May 16, 1978Assignee: Fuji Photo Film Co., Ltd.Inventors: Ryuji Shirahata, Masaaki Suzuki, Yasuyuki Yamada, Tatsuji Kitamoto, Shin-ichiro Dezawa
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Patent number: 4069164Abstract: In a process for producing ferromagnetic powder which comprises adding an aqueous solution containing Co.sup.+2 ions, with or without another cation or cations, and an alkali solution to a suspension of ferromagnetic iron oxide, and heating the mixture to produce ferromagnetic iron oxide containing the metal provided by such an ion (s), the improvement wherein the heating is carried out in the presence of an oxidizing agent.Type: GrantFiled: July 1, 1976Date of Patent: January 17, 1978Assignee: Fuji Photo Film Co., Ltd.Inventors: Shin-ichiro Dezawa, Koji Sasazawa, Tatsuji Kitamoto
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Patent number: 4066565Abstract: Co- and Fe-containing ferromagnetic iron oxide powder having a high coercive force and improved stability to heat and pressure is produced by adding an aqueous alkali solution, an aqueous solution containing Co.sup.+2 ions, and an aqueous solution containing not more than 1 equivalent, based on the Co.sup.+2 ions, of Fe.sup.+3 ions to a suspension of a ferromagnetic iron oxide, and heating the mixture at a temperature of at least about 80.degree. C, preferably 90.degree. to 105.degree. C. The ferromagnetic iron oxide powder is especially suitable for producing magnetic recording media.Type: GrantFiled: July 2, 1976Date of Patent: January 3, 1978Assignee: Fuji Photo Film Co., Ltd.Inventors: Koji Sasazawa, Shin-Ichiro Dezawa, Tatsuji Kitamoto
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Patent number: 4066564Abstract: A Co- and Fe-containing ferromagnetic iron oxide powder having a high coercive force and improved stability to heat and pressure is produced by adding an aqueous alkali solution, an aqueous solution containing Co.sup.+2 ions, and an aqueous solution containing not more than 1 equivalent, based on the Co.sup.+2 ions, of Fe ions to a suspension of ferromagnetic iron oxide, and heating the mixture at a temperature of at least 80.degree. C in the presence of an oxidizing agent. The ferromagnetic iron oxide powder is especially suitable for producing magnetic recording media.Type: GrantFiled: July 2, 1976Date of Patent: January 3, 1978Assignee: Fuji Photo Film Co., Ltd.Inventors: Koji Sasazawa, Shin-Ichiro Dezawa, Tatsuji Kitamoto
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Patent number: 4016057Abstract: Ferromagnetic particles having a high squareness ratio, high coercivities, and stable magnetic properties are prepared by electrolyzing ferromagnetic particles in an aqueous electrolyte using a cathode carrying ferromagnetic particles. The ferromagnetic particles thus treated may be then subjected to a heat treatment, if desired. When the ferromagnetic particles are iron oxide particles, the aqueous electrolyte contains a compound of a transition element.Type: GrantFiled: December 1, 1975Date of Patent: April 5, 1977Assignee: Fuji Photo Film Co., Ltd.Inventors: Shin-ichiro Dezawa, Yasuo Tamai