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:
Mar. 14, 1989
Filed:
Jul. 28, 1987
Nobuo Ogata, Nara, JP;
Yasuo Nakata, Nara, JP;
Hideaki Satou, Nara, JP;
Toshiyuki Tanaka, Osaka, JP;
Etsuji Minami, Nara, JP;
Yoshio Yoshida, Nara, JP;
Yukio Kurata, Tenri, JP;
Teruaki Inoue, deceased, late of Nara, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
A focusing error detector comprises a light source, a collimator lens for making parallel the pencil of rays emitted by the light source, an objective lens which focuses the parallel pencil of rays to form a beam spot on a data-recording disc with data tracks and guide tracks formed thereon and which receives the pencil of rays reflected from the data-recording disc, an optical system for forming a beam spot from the reflected pencil of rays incident to the objective lens, and an optical detector having a plurality of divided optical sensor blocks for receiving the formed beam spot so as to detect the focusing error of the beam spot formed on the data-recording disc on the basis of the configuration of the received beam spot.