Patent ID: 8547815
Filing Date: 2013-10-01
Classification: G11B

Abstract:
1. An optical pickup device adapted to interface with a multi-layer optical disc having a plurality of recording layers, comprising: a semiconductor laser diode which emits an optical flux; an objective lens which converges the optical flux emitted from said semiconductor laser diode and radiates the optical flux to an optical disc; an optical branching element which branches an optical flux reflected from said optical disc; and a photodetector which receives an optical flux branched by said optical branching element and has a plurality of light receiving parts, wherein: said optical branching element has three areas A, B and C; said area C includes a center of said optical branching element; said area A is spaced in a track direction of the optical disc relative to said area C; said area B is spaced in a radial direction of the optical disc relative to said area C; said photodetector detects a reproduction signal from optical fluxes diffracted in said areas A, B and C; said plurality of light receiving parts which detect the beam diffracted in said area A of said optical branching element are disposed separated from light receiving planes which receive diffracted beams from other areas and aligned in a direction substantially perpendicular to a direction corresponding to the track of said optical disc.