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:
Aug. 04, 1992
Filed:
May. 22, 1991
Pioneer Electronic Corporation, Tokyo, JP;
Abstract
The light receiving surface of the light receiving element, which receives reflected light from an information recorded disc, is divided into sections along lines passing through the center of the surface which run parallel to and perpendicular to the direction of tracking and which also run at an angle of 45 degrees to the first two lines. The tracking errors are detected either by a push-pull method or a heterodyne method. The two methods are combined and alternately switched into operation depending on whether information is being written into or read from the information recording disc. The push-pull method uses a pair of opposing, divided light receiving surfaces disposed in the direction of tracking and the heterodyne method uses two pairs of opposing, divided surfaces disposed diagonally or at an angle of 45 degrees to the direction of tracking.