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:
Sep. 19, 1989
Filed:
Feb. 02, 1988
Koichiro Nishikawa, Tokyo, JP;
Asahi Optical Co., Ltd., Tokyo, JP;
Abstract
According to an optical system of an optical pickup of the present invention, beam is split into two portions by a light refracting member which is disposed between a condenser lens and a light receiving element, a portion of beam entering into the light refracting member is utilized for detecting tracking errors, and the remaining portion of beam which is not permitted to enter into the light refracting member is utilized for detecting focussing errors by a knife edge test. With the above-mentioned constitution of the optical system, a tracking error composition is prevented from interferring with the focussing error detection and, at the same time, both the tracking errors and focussing errors can be detected by one light receiving element. Thus, the number of component parts can be reduced and the optical system itself can be made compact.