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:
Dec. 12, 1995
Filed:
Jun. 08, 1993
Toyoki Taguchi, Yokohama, JP;
Toshihiro Sugaya, Ibaraki, JP;
Hisashi Yamada, Yokohama, JP;
Kei Shimura, Yokohama, JP;
Isao Hoshino, Yokohama, JP;
Masahiko Tanaka, Yokohama, JP;
Teruo Murakami, Yokohama, JP;
Hiroharu Satoh, Tokyo, JP;
Hiromichi Kobori, Yokohama, JP;
Sadanari Fujimoto, Tokyo, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
An optical disk apparatus includes a semiconductor laser for emitting a light beam, and an automatic power control or APC circuit for driving the laser. A compound prism structure is optically coupled to the laser in an optical head section, and defines a first optical path for causing a front laser light to be projected onto a rotating optical disk and guiding a reflected light therefrom toward a first photodetector, and a second optical path for guiding a part of the reflected light toward a second photodetector. An output signal of the first photodetector is used to generate a reproduced information signal. An output signal of the second photodetector is fed back to the APC circuit as a front light monitor signal. A part of a laser control signal internally generated in the APC circuit is supplied through a wiring line to a noise reduction circuit as a laser noise monitor signal. The noise reduction circuit subtracts this noise monitor signal from the reproduced information signal to provide a noise-suppressed information signal.