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:
Oct. 31, 2006
Filed:
Dec. 12, 2002
Kenji Fujiune, Takatsuki, JP;
Yuichi Kuze, Settsu, JP;
Kenji Kondo, Kadoma, JP;
Shinichi Yamada, Katano, JP;
Katsuya Watanabe, Nara, JP;
Kenji Fujiune, Takatsuki, JP;
Yuichi Kuze, Settsu, JP;
Kenji Kondo, Kadoma, JP;
Shinichi Yamada, Katano, JP;
Katsuya Watanabe, Nara, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical disk apparatus includes an optical detector which has light receiving areas divided nearly concentrically with an optical beam and outputs a signal corresponding to the amount of the reflected light from an optical disk. A surface vicinity detecting section adds up signals from all the light-receiving areas of the optical detector and outputs a detection signal. The detection signal continuously varies so as to have one maximum level while a beam spot of the optical beam moves from the surface of the information medium to the information plane. An information plane detecting section judges that the focus or the beam spot of the optical beam comes closer to the information plane of the optical disk by detecting the gradient of the detection signal. An approach of a condensing lens and the optical disk is judged based on the judgment results, and thus a collision of the condensing lens and the optical disk can be prevented.