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:
Jul. 21, 1987
Filed:
Aug. 26, 1983
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 44 ; 369 54 ; 369 58 ;
Abstract
In a disc playback apparatus using an optical pickup or the like, any flaws on a track of the disc are detected using: a first level detector for detecting a maximum value level of a recording information signal of an output of the pickup; a second level detector for detecting a change of the maximum value level of the recording information signal; and a comparator for comparing outputs of the above first and second level detectors. When any flaws are detected, a driving signal of a driving device for the pickup is held to a fixed reference potential.