DEVICE AND METHOD FOR DETECTING DEFOCUS ERROR SIGNAL IN OPTICAL PICKUP AND FOR DETECTING SEEK DIRECTION USING THE SAME

摘要

PURPOSE: A device and a method for detecting a defocus error signal in an optical pickup and for detecting a seek direction using the same are provided to have a high precision and correctness in detecting the defocus error signal without being affected by a tilt of a recording medium, detrack, and a shift of an objective lens. CONSTITUTION: A light detector(10) has a first to third light collecting areas(A,B,C) distributively arranged in a direction(R) corresponding to a radial direction of a recording medium. A differential unit(30) differentiates between a sum signal(a+c) of signals(a,c) detected in the first and third light collecting areas(A,C) and a signal(b) detected in the second light collecting area(B), to output a defocus error signal(dFE). Each of the first or third light collecting areas(A,B,C) of the light detector(10) has a smaller width in a direction(R) corresponding to a radial direction and a wider width in a direction(T) corresponding to a tangential direction, and optical-to-electric converts incident light by being reflected and diffracted in the recording medium to output the first or third detection signals(a,b,c).