Patent ID: 7800986
Filing Date: 2010-09-21
Classification: G11B

Abstract:
1. An optical pickup for recording or reproducing an information signal in an optical disc, comprising: a light source for emitting a light beam toward the optical disc; an objective lens for focusing the light beam emitted from the light source onto a recording surface of the optical disc; and a photodetector for receiving the light beam reflected by the recording surface of the optical disc and outputting a signal corresponding to an intensity of the received light beam, wherein an area of a spot of the light beam received by the photodetector is asymmetric in both a radial direction and a tangential direction of the optical disc due to blocking of a portion of the light beam before the light beam reaches the photodetector, and wherein a lens shift signal for the objective lens is detected by a controller on the basis of the signal output from the photodetector, the controller controlling the objective lens to follow the optical disc.