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:
Dec. 01, 1992
Filed:
Sep. 28, 1989
Applicant:
Inventor:
Kazuo Isaka, Odawara, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 47 ; 369 54 ; 369 4425 ; 369 4434 ;
Abstract
In an optical disk apparatus for recording and reproducing data using light beams, the light reflected from a record mark area provided on an optical disk is detected and the amplitude of the signal corresponding to the light is held; the record mark is composed of long pits and long unrecorded areas. This amplitude is compared with that of the signal relative to the light from a data recording area of the optical disk. If the comparison result has a predetermined relation between both signals, an output signal with a prescribed level is produced. This output signal is used to assure the quality of the recorded data.