US006203934Bl  (12)  United States Patent  Naoe et al.  (10)  Patent No.:  US 6,203,934 Bl  Mar.20,2001  (45)  Date of Patent:  (54)  MAGNETIC RECORDING MEDIUM  (75)  Inventors:  Koji Naoe; Kiyomi Ejiri; Naoto Abe,  all of Kanagawa (JP)  (73)  Assignee:  Fui Photo Film Co., Ltd.,  Kanagawa  (JP)  ( *)  Notice:  Subject to any disclaimer, the term of this  patent is extended or adjusted under 35  U.S.C. 154(b) by  O  days.  (21)  Appl. No.:  09/169,189  (22)  Filed:  Oct. 8, 1998  (30)  Foreign Application Priority Data  Oct. 14, 1997  (JP) ................................................... 9-280629  Jan. 7, 1998  (JP) ................................................. 10-001760  (51)  Int. Cl.7  ........................................................  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(List continued on next page.)  U.S. application No. 08/976,822, filed Nov.  24, 1997,  Satoshi Matsubaguchi, abandoned; filed as CIP 09/324,754.  The Advantages of the Thin Magnetic Layer on a Metal  Particulate Tape, IEEE Transactions on Magnetics, vol. 29,  No. 6, Nov. 1993.  Development of Particulate Recording Media with Ultra thin  Magnetic Layer, IEICE Trans Electron, vol. E78-C. No. 11,  Nov. 1995.  Enabling technologies for a 100MB 3.5 floppy (ZIP™) disk  drive, 220/SPIE vol. 2604 (No Date Available).  Primary Examiner-Bernard  Pianalto  (74)  Attorney, Agent, or Firm----Stroock  &  Stroock  &  Lavan  LLP  A magnetic recording medium is described, which com› prises a support having thereon a magnetic layer comprising  a ferromagnetic metal powder and a binder resin, wherein  the coercive force (He) of the magnetic layer is from 2,100  to 3,000 Oe, SFD (switching field distribution) of the  magnetic layer is 0.30 or less, and an average thickness: d of  the magnetic layer is in the range of: d~ recording wave› length A/4.  OTHER PUBLICATIONS  (57)  ABSTRACT  35 Claims, No Drawings  FOREIGN PATENT DOCUMENTS 