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:
Apr. 22, 2008
Filed:
Nov. 12, 2004
Emi Kitano, Nara, JP;
Masayoshi Nakamura, Osaka, JP;
Yoshiyasu Nakayama, Osaka, JP;
Yasuo Ueda, Osaka, JP;
Emi Kitano, Nara, JP;
Masayoshi Nakamura, Osaka, JP;
Yoshiyasu Nakayama, Osaka, JP;
Yasuo Ueda, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
In an optical information reproduction apparatus having optical beam sources having at least two types of wavelengths, an object lens may be damaged by colliding with an information recording medium while driving a focus servo, which is caused by a fake signal generated due to an incompatibility of the wavelength in use with the information recording medium. To solve such a problem, in case the type of the information recording medium is unrecognizable and a focus servo is led in by using the optical beam source having the first wavelength, the focus servo is led in by using the second focus servo lead-in unit which is driven by an output of a near focus point detection unit during an operation of a second focus search unit which renders the object lens move away from the information recording medium.