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:
Apr. 11, 1995
Filed:
Aug. 18, 1993
Applicant:
Inventor:
Akihiko Doi, Tokyo, JP;
Assignee:
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 4428 ; 369 4429 ; 369 4434 ;
Abstract
A head signal process circuit 18 generates a focus error signal representing the distance between an optical disc 11 and an objective lens 20 using a detection signal detected by an optical detector of an optical head 14. The focus error signal is sent to a non-linear amplifying circuit 21. The level of the focus error signal in the vicinity of a servo point is amplified. The level of the focus error signal apart from the servo point is suppressed. The output of the non-linear amplifying circuit 21 is sent to an A/D converter 22. Thus, a servo digital signal is generated.