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:
Jan. 14, 2003
Filed:
Jul. 06, 1999
Kunikazu Ohnishi, Yokosuka, JP;
Takeshi Shimano, Tokorozawa, JP;
Shigeru Nakamura, Tachikawa, JP;
Masayuki Inoue, Yokohama, JP;
Yukio Fukui, Machida, JP;
Yasuyuki Sugi, Ibaraki, JP;
Shinji Fujita, Yokohama, JP;
Mitsuhiko Ota, Yokohama, JP;
Other;
Abstract
It is desirable to greatly reduce the disturbance that arises in a focusing error signal by a astigmatic detection method and offset that arises in the tracking error signal by a push-pull method when reproducing various information storing disks, such as a DVD-RAM disk. It is also desirable to provide an optical disk apparatus which is able to reproduce a variety of high density optical disks, such as DVD-RAM and DVD-ROM disks, as well as conventional disks, such as CD, CD-ROM, CD-R disks, by using a simple optional head. For this purpose, an optical disk apparatus irradiates three optical beams produced by a diffraction grating on the specified position of an optical disk and detects reflected light using a specified optical detector divided into twelve parts.