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:
Jan. 11, 1994
Filed:
May. 06, 1992
Kunikazu Ohnishi, Chigasaki, JP;
Tohru Sasaki, Yokohama, JP;
Masayuki Inoue, Yokohama, JP;
Michio Miura, Yokohama, JP;
Akira Saito, Odawara, JP;
Kazuo Shigematsu, Saitama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An optical recording/reproducing apparatus includes a plurality of semiconductor lasers, an objective lens for focusing light beams from the semiconductor lasers on an optical disk to form a plurality of light spots, and a correction unit for reducing an offset in a tracking signal occurring concomitantly with relative position correction for the light spots. The correction unit includes a rotary wedge-shaped prism disposed in an optical path through which a laser beam incident on the optical disk and a reflection laser beam from a light spot on the disk pass in opposite directions. The shape, refractive index and initial installation angle of the wedge-shaped prism are designed to have predetermined values that cancel the position shift of the laser beam on the objective lens surface occurring concomitantly with deflection of the laser beam.