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:
Mar. 12, 1991
Filed:
Dec. 04, 1989
Applicant:
Inventor:
Teruo Fujita, Kyoto, JP;
Assignee:
Mitsubishi Denki K.K., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 4441 ;
Abstract
The present invention has an object to provide a focus sensor or tracking sensor for an optical recording and reproducing device, which has a simplified optical system whose adjustment is much facilitated. The operational principle of this device is to produce a focusing error signal or tracking error signal by vibrating light spot on an optical disc with a small amplitude to scan interference fringes produced in the far field on an optical disc on the basis of a periodicity of information tracks of the optical disc and processing output signals of an optical sensor arranged in the far field.