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:
May. 02, 1995
Filed:
Dec. 10, 1993
Hitachi, Ltd., Tokyo, JP;
Abstract
An optical disk unit has an optical system which is separated into a movable head assembly and a fixed optical system so that the movable head is made light weight. The movable head has an objective lens, an objective lens driving unit for focusing the objective lens, and a head moving unit for moving the whole movable head in the radial direction of an optical disk. The fixed optical system has a galvanomirror for deflecting the light emitted from a laser beam source and causing it to fall on the objective lens of the movable head, and detectors for receiving the light of the optical spot formed by the objective lens which is reflected from the optical disk. The galvanomirror is provided with a first mirror for reflecting the light emitted from the beam source to a plane intersecting the rotational shaft at right angles and directing the light to a fixed mirror, and a second mirror for deflecting the light reflected from the fixed mirror and directing the light to the objective lens. As a result, when the galvanomirror is rotated, the light reflected from the second mirror is constantly passed through a portion near the focal point of the objective lens of the light source side and falls on the objective lens.