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:
Oct. 01, 1985
Filed:
Sep. 29, 1982
Toru Musha, Hachioji, JP;
Kenichi Ito, Hachioji, JP;
Olympus Optical Co., Ltd., , JP;
Abstract
A tracking error of a light spot focused on an optical record disc by means of an objective lens with respect to an information track recorded on the disc is detected by processing outputs from a light detector arranged in a far field of the track and having four light receiving regions on which a light reflected by the disc is incident. A tracking error signal of a differential detection system, i.e. a difference between two sums of outputs from two pairs of two regions aligned in a direction tangential to the track is derived, and a push-pull signal, i.e. a difference between two sums of outputs of two pairs of two light receiving regions aligned in a radial direction is also obtained. Zero crossings of the push-pull signal are detected to produce sampling pulses and the tracking error signal of differential system is sampled by the sampling pulses to derive a tracking error signal which is substantially free from disturbance due to a possible shift of the light impinging upon the light detector with respect to the optical axis of objective lens.