Patent ID: 6128259
Filing Date: 2000-10-03
Classification: G11B

Abstract:
An optical pickup apparatus comprising:a laser diode which forms three beams, comprising a main beam and two sub-beams;an objective lens which focuses the three beams onto an optical disk as three spots, comprising a main spot and two sub-spots; anda detective lens which captures the portions of the three beams which are reflected from the optical disk and focuses them towards a knife edge, the knife edge directing the three reflected beams to a photo detector for detecting a tracking error signal;wherein the sub-beam which is directed to a portion of the knife edge with a lower shading rate has its corresponding sub-spot located at a position on the optical disk ahead of the main spot in a recording direction, and the sub-beam which is directed to a portion of the knife edge with a higher shading rate has its corresponding sub-spot located at a position on the optical disk behind the main spot in the recording direction.