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:
Jul. 06, 2010
Filed:
Jun. 15, 2006
Tetsuya Ogata, Kanagawa, JP;
Tatsuo Mikami, Kanagawa, JP;
Tetsuya Ogata, Kanagawa, JP;
Tatsuo Mikami, Kanagawa, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
An optical pickup unit for recording information on and/or reproducing information from a multilayer information recording medium including multiple recording surfaces in each of which a guide groove on which the information is to be recorded is spirally formed is disclosed. The optical pickup unit includes a light source, a diffraction element configured to split the light beam emitted from the light source into a main light beam and first and second sub light beams, an objective lens for focusing the main and sub light beams onto a recording surface of the multilayer information recording medium, and multiple light receiving elements each divided into light receiving parts so as to receive the main and sub light beams reflected from the recording surface. The focused first and second sub light beams are disposed at respective positions at least 3/2 tracks away from the focused main light beam on the recording surface.