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:
Jul. 08, 1997
Filed:
Sep. 19, 1995
Hajime Kobayashi, Tokyo, JP;
NEC Corporation, , JP;
Abstract
A photosensor receives laser light reflected from an optical disk with a two-segmented photodetecting surface. A relative speed detecting section binarizes a difference signal of output signals of the photosensor, and detects time points when the laser light is located at the centers of tracks and grooves of the optical disk. When a detected interval is longer than a preset value, the relative speed detecting section outputs a speed detection pulse having a preset pulse width. A track detecting section binarizes a sum signal of the output signals of the photosensor, detects time points when the laser light is located at a track edge, and outputs a track detection pulse having a preset pulse width. A loop switch turns on/off a tracking servo loop in accordance with a tracking start signal that is generated by an AND circuit and a D flip-flop.