Patent ID: 6473387
Filing Date: 2002-10-29
Classification: G11B

Abstract:
An optical disc apparatus that is adapted for a plurality of kinds of optical discs whose cover layers are different in thickness, said apparatus comprising:a light source portion that has a plurality of emission points in close proximity to each other, said emission points emitting divergent laser beams at different wavelengths, respectively, said emission points being switched in accordance with the thickness of said cover layer; an objective lens for converging divergent laser beam from said light source portion onto an information layer of said optical disc through said cover layer thereof; a light receiving portion that receives the reflected light beam from said optical disc to produce signals; and a focusing mechanism that moves said objective lens such that the distance between said objective lens and said optical disc increases as the thickness of said cover layer decreases, wherein the distances between said respective emission points and the surfaces of said cover layers are constant regardless of the thickness of said cover layer.