| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect an optimum servo parameter by one objective lens shifting operation. <P>SOLUTION: A detection control unit 20 gradually sets a sub PP gain k for each gradual shifting of an objective lens 10 in a tracking direction. For each combination of each shifting voltage and each sub PP gain k, a differential PP balance calculation unit 19 calculates a differential PP balance value BL to store it in a memory 21. The detection control unit 20 calculates, for each setting value of the sub PP gain k, a degree of influence of the shifting voltage of the objective lens 10 on a DPP balance value BL. The detection control unit 20 detects, based on an approximate equation indicating a relationship between the degree of influence and the sub PP gain k, a value of the sub PP gain k when the degree of influence is lowest as an optimum servo parameter. Thus, even when a relationship between a degree of influence of a controlled variable of servo control on an error signal and a servo parameter is not linear, an optimum servo parameter can be detected by one changing operation of the controlled variable. <P>COPYRIGHT: (C)2012,JPO&INPIT |
