OPTICAL DISC DRIVE

摘要

PURPOSE: An optical disc drive is provided to detect the depth of an information surface of an optical disc and discriminate the type of a loaded optical disc. CONSTITUTION: A photodetector(15) detects a reflected light in an information surface, and outputs a reflected light signal. A spherical aberration generator(16) generates a minimum spherical aberration when a beam spot is located at a reference depth on the basis of the depth of the information surface of plural types of optical discs. A focus driver(22) controls the position of a lens(13), and moves the beam spot perpendicularly to the information surface. A light quantity detector(40) detects a light quantity signal indicating the quantity of the reflected light on the basis of the reflected light signal outputted according to the movement of the beam spot. A discriminator(42) discriminates the type of a loaded optical disc on the basis of the degree of symmetry of the waveform of the light quantity signal.