Patent ID: 6654323
Filing Date: 2003-11-25
Classification: G11B

Abstract:
A method of tracking servo for an optical pickup device, which uses a diffraction means to divide a beam emitted from a laser light source into one main beam and two side beams, and allows a main photo detector to receive the main beam for reading or writing of signals and servo error detection, while allowing individual side photo detectors to receive two side beams for tracking error detection, comprising the steps of:generating each individual push pull signal with a photo detector composed of said main photo detector having four light receiving sections crosswise and said side photo detectors respectively having two light receiving sections left and right; and generating a tracking error signal on the basis of operational output from the push pull signals resulting from respectively canceling amounts of DC offset produced in the each push pull signals in the respective photo detectors, wherein generating the tracking error signal includes storing DC offsets associated with each detected push pull signal when tracking servo is off, and dividing the stored DC offsets by additional push null signals of the main beam and two side beams, respectively, wherein said additional push pull signals are detected when tracking servo is on.