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:
Oct. 27, 1987
Filed:
Nov. 26, 1984
Hitachi, Ltd., Tokyo, JP;
Hitachi Maxell Ltd., Osaka, JP;
Abstract
A record carrier has a circular disc-shaped substrate on which a recording layer capable of optically writing information therein is disposed, and is so constructed that a plurality of circumferential reference tracks extending in a rotating direction are provided at radial intervals, the reference track being put into an optically detectable structure so as to function as an optical guide for recording information between the adjacent reference tracks. A first light beam and a second light beam are condensed by an identical objective lens so as to be respectively focused on the recording layer of the record carrier. As one of the reference tracks is being tracked by the first light beam, the second light beam is diffracted by a light diffracter so as to be spaced from the first light beam on the record carrier by desired track pitches in the radial direction thereof. Thus, data is sequentially recorded at predetermined pitches in a recording area located between the reference tracks by means of the second light beam.