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:
Mar. 08, 2005
Filed:
Mar. 14, 2002
Yoshiki Ono, Yokohama, JP;
Tatsuya Kurihara, Yokohama, JP;
Shigemi Sato, Yokohama, JP;
Sumikazu Oki, Yokohama, JP;
Yoshiki Ono, Yokohama, JP;
Tatsuya Kurihara, Yokohama, JP;
Shigemi Sato, Yokohama, JP;
Sumikazu Oki, Yokohama, JP;
NHK Spring Co., Ltd., Yokohama, JP;
Abstract
A magnetic marker comprises a magnetically switchable wire and a magnetic casing that covers the magnetically switchable wire. The magnetically switchable wire is formed of a magnetic material that undergoes occurrence of sharp magnetic inversion when an alternating field of intensity higher than its coercive force is applied to it. The magnetic casing is formed of a magnetically hard or semihard magnetic material and can apply a bias magnetic field to the magnetically switchable wire to prevent magnetic inversion of the magnetically switchable wire. Heat-treated portions and high-coercivity regions, which are not heat-treated, are formed alternately in the longitudinal direction on the magnetic casing. The heat-treated portions are given magnetic properties different from magnetic properties essential to the magnetic casing by heat treatment such as annealing.