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. 20, 2009
Filed:
Dec. 27, 2005
Yi-chung Lee, Hsinchu, TW;
Hsiang-yi Fu, Hsinchu, TW;
Tun-chieh Lee, Hsinchu, TW;
Fu-hsiang Chen, Hsinchu, TW;
Yi-Chung Lee, Hsinchu, TW;
Hsiang-Yi Fu, Hsinchu, TW;
Tun-Chieh Lee, Hsinchu, TW;
Fu-Hsiang Chen, Hsinchu, TW;
Lite-On It Corp., Taipei, TW;
Abstract
In a layer jump and focusing control method, a first focusing error signal is generated according to the differential astigmatism method in a closed-loop focusing control manner when focusing on the first recording layer. A second focusing error signal is generated according to the astigmatic method in an open-loop focusing control manner when a first layer-jumping procedure is performed to shift a focusing position from the first recording layer to the second recording layer. Then, the completion of the first layer-jumping procedure is determined according to the second focusing error signal, for example when the second focusing error signal passes the zero crossing point and exceeds a threshold level. Afterwards, a third focusing error signal is generated according to the differential astigmatism method in a closed-loop focusing control manner when focusing on the second recording layer.