Optical disc drive with clock synchronization and rotational speed detection

Abstract

An optical disc drive includes: a motor for rotating an optical disc thereon; a photoelectric transducer for converting a light beam, reflected from or transmitted through the disc, into an electric signal; a clock sync signal reader for extracting and outputting a read signal, representing a clock synchronization mark, from the electric signal; a clock generator for generating a clock signal having a variable frequency; a phase locking controller for controlling the clock generator to synchronize the clock signal in phase with the output signal of the clock sync signal reader; and a mechanism for displacing a light beam spot toward a target track on the disc. During a seek operation of displacing the light beam spot toward the target track, the clock generator is controlled to obtain a frequency to be expected on the target track and output a clock signal having the expected frequency.