The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 29, 1980
Filed:
Jun. 12, 1975
Applicant:
Inventors:
Koji Sasazawa, Odawara, JP;
Shigeo Komine, Odawara, JP;
Tatsuji Kitamoto, Odawara, JP;
Goro Akashi, Odawara, JP;
Assignee:
Fuji Photo Film Co., Ltd., Minami-ashigara, JP;
Primary Examiner:
Int. Cl.
CPC ...
H01F / ;
U.S. Cl.
CPC ...
428403 ; 427 48 ; 427128 ; 427215 ; 427217 ; 427377 ; 4273833 ; 428900 ;
Abstract
A magnetic iron oxide having a large coercive force and an improved squareness ratio prepared by coating the surface of needle-like particles of magnetic iron oxide with a cobalt compound, placing the coated iron oxide particles in a unidirectionally oriented magnetic field thereby orienting the particles in the direction of the magnetic field, and heat-treating the needle-like particles in this state with the application of an external magnetic field, or heat-treating the needle-like particles in a magnetized state.