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:
Aug. 04, 1998
Filed:
May. 27, 1997
Hideji Morita, Higashihiroshima, JP;
Yasusi Seike, Toyonaka, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
In an optical recording and reproducing device, an aperture member is provided in a region between an objective lens and a reflection mirror so as to be freely pushed into and pulled out of a light flux, and a masking member is provided on the objective lens. The masking member has an inside diameter smaller than an aperture diameter of the aperture member, and has an outside diameter greater than the aperture diameter of the aperture member. The aperture member has an outline size greater than a size of an aperture of an objective lens holding member. Therefore, an effective numerical aperture of the objective lens is determined in accordance with the inside diameter of the masking member in the case where the aperture member is placed in the light flux, whereas the effective numerical aperture is determined by the aperture of the objective lens holding member in the case where the aperture member is not placed in the light flux. With this arrangement, stable reproduction of a compact disk without being affected by a shift of the objective lens is enabled, while reproduction of a high-density disk is also enabled.