HIGH DENSITY OPTICAL DISC HAVING A DIFFERENCE THICKNESS BETWEEN INFORMATION AREA AND CLAMPING AREA, AND OPTICAL DISC DEVICE THEROF

摘要

PURPOSE: A high density optical disc having a difference thickness between information area and clamping area, and an optical disc device thereof are provided to prevent the collision between a high density optical disc and an objective lens. CONSTITUTION: A BD(Blu-ray Disc, 20) has a clamping area, an information field and a transition area. The information field comprises the record layer. The record layer is formed in the side near the light entering side which the BD is normally installs. The transition area is formed between the clamping area and information field. A declined part is formed on the transition area.