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:
Feb. 15, 2000
Filed:
Apr. 22, 1998
Yoichi Tsuchiya, Hashima, JP;
Yasuyuki Kanou, Hashima, JP;
Seiji Kajiyama, Ibi-gun, JP;
Koichi Tada, Motosu-gun, JP;
Katsutoshi Hibino, Gifu, JP;
Shigeki Hori, Ogaki, JP;
Sanyo Electric Co., Ltd., Moriguchi, JP;
Abstract
An optical pickup apparatus including a polarization plane rotary unit arranged between a semiconductor laser and an objective lens, and a polarizing film arranged between the polarization plane rotary unit and the objective lens. The polarization plane rotary unit includes liquid crystal, two glass plates sandwiching the liquid crystal, and transparent electrodes patterned to a predetermined configuration on an inner face of these glass planes. The polarization plane rotary unit permits passage of the laser beam without rotating the plane of polarization of the entire laser beam at the time of recording, and permits passage of the laser beam with the plane of polarization of the center portion of the laser beam rotated and the plane of polarization of the remaining outer portion of the laser beam not rotated at the time of reproduction. Only the outer portion of the laser beam is focused on a magneto-optical disk in a reproduction mode, so that a main beam of a small spot is formed by mutual interference. Since the plane of polarization of the laser beam directed on the magneto-optical disk is not rotated, the Kerr angle of rotation can be detected at high accuracy. As a result, the reproducibility is improved.