Patent ID: 7193941

Claim:
An optical disc drive for reading and/or writing information from/onto an optical disc by focusing a light beam onto the disc, the optical disc including a clock synchronization mark and a data section on which the information is recordable, the optical disc drive comprising: a motor for rotating the optical disc thereon; a photoelectric transducer for converting the light beam, reflected from or transmitted through the optical disc, into an electric signal and outputting the electric signal; a bandpass filter for extracting and outputting a signal in a particular frequency band from the electric signal that has been output from the photoelectric transducer, the frequency band being variable; a clock sync signal reader for extracting and outputting a read signal, representing the clock synchronization mark, from the output signal of the bandpass filter; a clock generator for generating a clock signal having a variable frequency; a phase locking controller for controlling the clock generator in such a manner as to synchronize the clock signal in phase with the output signal of the clock sync signal reader; a linear velocity detector for detecting the linear velocity of the optical disc; and a frequency band controller for controlling the frequency band to be extracted by the bandpass filter in accordance with the output of the linear velocity detector, wherein while the optical disc drive is performing a seek operation to displace the light beam spot toward a target track on the optical disc, the frequency band controller controls the frequency band so as to pass a clock frequency to be expected on the target track before the seek operation is finished, the optical disc drive further comprising: a mechanism for displacing a spot of the light beam on the optical disc toward a target track on the optical disc; and a rotational speed detector for detecting the rotational speed of the optical disc, the rotational speed being changeable with where the light beam spot is located on the optical disc, wherein the linear velocity detector detects the linear velocity at a frequency to be determined by the detected rotational speed of the optical disc and a target rotational speed at a zone to which the target track belongs, and wherein after the seek operation, the frequency band controller continuously changes the frequency band to be extracted by the bandpass filter until rotational speed of the motor substantially reaches target rotational speed to be expected on the target track.