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. 25, 1989
Filed:
Feb. 20, 1986
Kaoru Toki, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
An apparatus and a method for recording, reading and erasing information, which use, as a recording medium, a magnetic film having vertical magnetic anisotropy characteristics and record, read and erase information by means of a laser beam and an external magnetic field applied to the magnetic medium. These are characterized in that the application of the external magnetic field to the recording medium is controlled by controlling the magnetic field provided by a permanent magnet put at a predetermined distance from the recording medium. For controlling the magnetic field, means for applying an external magnetic field to a recording medium is employed, which comprises a permanent magnet, a magnetic core of a high magnetic permeability material comprising a pole piece attached to at least one pole of the permanent magnet and a lag piece integrally connected to the pole piece and having a wire wound therearound, and an electric current source supplying electric current to the wire wound of the core.