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:
Feb. 08, 2011
Filed:
Jul. 12, 2007
Kenya Yokoi, Kanagawa, JP;
Ryosuke Kasahara, Kanagawa, JP;
Kenya Yokoi, Kanagawa, JP;
Ryosuke Kasahara, Kanagawa, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A data readout method is disclosed that is able to read data from an optical disk capable of super resolution readout with high accuracy. The data readout method allows reading data recorded in an optical disk by irradiating a laser beam onto the optical disk. The method includes the steps of varying a light emission power level of the laser beam while the laser beam is irradiated onto the optical disk, and acquiring a reflectivity of the optical disk corresponding to each light emission power level; calculating a second derivative of a curve representing correlation between the reflectivity and the light emission power with respect to the light emission power; calculating an extreme value of the second derivative; and calculating an optimum readout power level for super resolution readout based on the extreme value.