Patent ID: 7826315

Claim:
An optical disc drive detecting information recorded in an optical disc using a light beam to reproduce or record data, comprising: an objective lens configured to irradiate the light beam to the optical disc; a drive coil configured to move the objective lens to an optical axis of the light beam; a divided receiving device having a plurality of light receiving elements dividing and detecting reflected light or transmitted light from the optical disc, and outputting a detection signal; a focus error detector configured to generate a focus error signal from a detection signal from each light receiving element of the divided receiving device; an amplitude detector configured to detect an amplitude of a signal high-pass-filtering an addition signal of each light receiving element; an intensity detector configured to detect an intensity of a signal low-pass-filtering an addition signal of each light receiving element; an amplitude determination section configured to determine whether or not the amplitude is larger than a first threshold value; intensity determination section configured to determine whether or not the intensity is larger than a second threshold value; and a focus position controller configured to supply a driving voltage to the drive coil so that a focus position of the light beam is controlled, the focus position controller supplying a driving voltage corresponding to the focus error signal to the drive coil when the amplitude is larger than the first threshold value, or when the amplitude is not larger than the first threshold value and the intensity is smaller than the second threshold value, and supplying a driving voltage having a constant voltage value to the drive coil regardless of the focus error signal when the amplitude is not larger than the first threshold value and the intensity is not smaller than the second threshold value.