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:
Nov. 03, 1992
Filed:
Nov. 21, 1990
Hitachi, Ltd., Tokyo, JP;
Abstract
A record carrier for recording, reproducing and erasing information. A circular disc-like substrate has a recording layer thereon such that information is written onto the recording layer by changing the direction of magnetization. A guide groove of a plurality of tracks is formed in advance and extends in the radial direction with intervals therebetween. Each track of the guide groove is divided into a plurality of sectors, each of which includes a header portion in which a header signal containing an address for distinguishing at least said sector is formed in advance with pits of a phase structure and a data portion adjacent to said header portion. The guide groove serves as an optical guide for a light beam which records, reproduces and erases information onto the data portion. A first detection system for detecting the light intensity of the reflected light from the record carrier and a second detection system for detecting the direction of polarization of the reflected light from the record carrier, and a level adjustment circuit for adjusting the levels of the header signal detected by the first detection system and the data signal detected by the second detection system are incorporated in this apparatus, whereby recording, reproducing and erasing information of any number of sectors are enabled.