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. 31, 1989
Filed:
Apr. 15, 1987
Takashi Ohnaka, Hirakata, JP;
Sanyo Electric Co., Ltd., Osaka, JP;
Abstract
When a recording track on a magnetic disc (10) is erased, a first erasing signal f.sub.1 with an upper limit of frequency (10 MHz) in a recording signal band is supplied through a magnetic head 14 over a period T.sub.1. Since the erasing signal f.sub.1 is attenuated and vibrated in a period T.sub.12, the residual component is minimized. A second erasing signal f.sub.2 with an upper limit of frequency (20 MHz) which is outside of the recording signal band and can be recording and reproduced by the magnetic head is supplied through the magnetic head 14 over a period T.sub.2, so that the residual component of the erasing signal f.sub.1 is erased. Since the erasing signal f.sub.2 is attenuated and vibrated in a period T.sub.22, the residual component is minimized.