Patent ID: 8085628

Claim:
A focus servo controlling method comprising: detecting a period of time that satisfies a first threshold condition in a focus pull-in mode, the first threshold condition set to determine a duration in which a focal point of an optical signal emitted from a pickup is passing through a cover layer of a disk, the determination made by using a first signal proportional to a detected portion of an optical signal reflected by the disk; generating a first state signal when the first signal first satisfies the first threshold condition; generating a second state signal when the first signal no longer satisfies the first threshold condition; and preventing focus servo control from being performed during a detected period of time between the first state signal and second state signal where the first signal first satisfies the first threshold condition since the operating mode entered into the focus pull-in mode, wherein a second threshold condition comprises a condition in which the magnitude of the first signal becomes equal to or greater than a third threshold value and after the lapse of a certain period of time becomes equal to or greater than a fourth threshold value set to be greater than the third threshold value.