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. 21, 1984
Filed:
Oct. 23, 1981
Tsutomu Shibata, Hachioji, JP;
Olympus Optical Co., Ltd., Tokyo, JP;
Abstract
A light beam emitted from a laser light source is made incident upon a video disc by means of an objective lens and a light flux reflected by the disc is made incident upon a light detector arranged in a far field of an information track of the disc. The light detector includes four light receiving regions divided in a track direction and a direction perpendicular to the track direction. A first sum of output signals from diagonally aligned two light receiving regions and a second sum of the remaining two light receiving regions are derived and then a sum signal and a difference signal of the first and second sums are formed. The difference signals are sampled by sampling pulses generated at positive going and/or negative going zero cross points of the sum signal to generate sampled values. A tracking error signal is obtained from sampled values.