Patent ID: 7315495

Claim:
A focus pull-in controller of an optical disk device, comprising: a focus error compensator filter configured to receive a focus error signal, compensate the focus error signal for amplitude and phase of the focus error signal, and output the compensated result as a first focus output signal; an upper limit value detector configured to detect and store an upper limit surface vibration value of the first focus output signal; a lower limit value detector configured to detect and store a lower limit surface vibration value of the first focus output signal; a focus error range setting unit configured to set a focus error search range based on the upper limit surface vibration value and the lower limit surface vibration value of the first focus error signal; an amplifier configured to multiply an output signal of the focus error range setting unit by a predetermined error margin coefficient K; a first mixer configured to sum an output signal of the upper limit value detector with an output signal of the amplifier; a second mixer configured to sum an output signal of the lower limit value detector with the output signal of the amplifier; and a triangular wave generator configured to generate a second focus control output signal in response to output signals of the first and second mixers.