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. 04, 2011
Filed:
Feb. 13, 2009
Ariyoshi Nakaoki, Tokyo, JP;
Kimihiro Saito, Saitama, JP;
Ariyoshi Nakaoki, Tokyo, JP;
Kimihiro Saito, Saitama, JP;
Sony Corporation, Tokyo, JP;
Abstract
An optical pickup device has a near-field optical system having a numerical aperture of NA>1; a first light source emitting a first light having a first wavelength; a second light source emitting a second light having a second wavelength; an optical system multiplexing the first light and second light and irradiating the multiplexed light onto an optical recording medium having at least two recording layers; a first photodetector detecting the first light returned from the recording medium a second photodetector detecting the second light returned from the recording medium; a controller obtaining a signal corresponding to distance between the near-field optical system and the recording medium based on the returned second light, and obtaining a reproducing signal and a tracking signal of the recording medium and a focus signal corresponding to the recording layer based on the returned first light; and a focus position adjustment mechanism moving a focus position of the first light under control of the focus signal.