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:
Jan. 22, 1985
Filed:
Nov. 25, 1981
Tuneo Yanagida, Hino, JP;
Olympus Optical Co., Ltd., , JP;
Abstract
In an opto-magnetic apparatus using an opto-magnetic record disc which has been uniformly magnetized in one direction perpendicular to a surface of the disc, an information signal recorded in the disc along a track is erased by irradiating the track to be erased with a laser light beam to heat the relevant track to a Curie point and by applying an external erasing magnetic field having a direction opposite to that of the uniform magnetization in the disc so as to magnetize the track in the other direction. In case of re-recording an information signal in the thus erased track, the information signal is first inverted and then the laser beam is modulated with the inverted information signal and the modulated laser beam is projected upon the erased track, while an external magnetic field having the same direction as that of the uniform magnetization in the disc is applied. The information signal may be alternatively recorded in the erased track without inverting the information signal together with an identifying signal denoting that the recorded information signal has a magnetization of the same direction as that of the uniform magnetizaton.