Patent ID: 7606122

Claim:
A layer-jumping and focusing control method for reading a data storage medium having first and second recording layers, the method comprising steps of: generating a first focusing error signal according to the differential astigmatism method in a closed-loop focusing control manner when focusing on the first recording layer; generating a second focusing error signal 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; determining the completion of said first layer-jumping procedure according to said second focusing error signal; and generating a third focusing error signal according to the differential astigmatism method in a closed-loop focusing control manner when focusing on the second recording layer; generating a fourth focusing error signal according to the astigmatic method in an open-loop focusing control manner when a second layer-jumping procedure is performed to shift the focusing position from the second recording layer to the first recording layer; and determining completion of said second layer-jumping procedure according to said fourth focusing error signal.