Patent Number: 6,167,019

Title: Optical Disc cd recording/reproducing apparatus recording/reproducing information to/from optical discs according to different standards

Abstract: An optical disc reproducing apparatus includes a semiconductor laser, an objective lens converging a laser beam from the semiconductor laser on a recording surface of an optical disc, a polarization plane rotating unit selectively rotating the plane of polarization of the laser beam according to the thickness of a substrate of the optical disc, and a polarizing filter selectively shading a peripheral portion of the laser beam having the rotated plane of polarization. In one embodiment, a numerical aperture changing unit includes a non-patterned twisted nematic liquid crystal, and the polarizing filter includes a polarizing film having a polarization characteristics at its peripheral portion.

Inventors: Tsuchiya; Yoichi (Hashima, JP), Kajiyama; Seiji (Ibi-gun, JP), Kanou; Yasuyuki (Hashima, JP), Ichiura; Shuichi (Hashima, JP)

Assignee: Sanyo Electric Co., Ltd.

International Classification: G11B 7/013 (20060101); G11B 19/12 (20060101); G11B 7/125 (20060101); G11B 7/00 (20060101); G11B 007/00 ()

Expiration Date: 12/26/2017