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. 22, 1992
Filed:
Feb. 08, 1991
Pioneer Electronic Corporation, Tokyo, JP;
Abstract
The light receiving element of the photo-detecting device of this invention has its light receiving area formed smaller than the diameter of a beam reflected from an optical information recorded disc. This makes it possible for the tracking error signal to be taken from a central area of the beam spot where the light intensity is high. This minimizes the dc offset caused by misalignment between the objective lens and the beam axis. The light receiving surface of the element is divided into at least four sections along a line at 45 degrees to the direction of tracking. A difference is taken between the light quantities received by two divided light receiving surfaces disposed perpendicular to the tracking direction. This differential signal allows adjustment to be made of an angle between the disc and the photo-detecting device in the direction perpendicular to the tracking direction.