HIGH-DENSITY OPTICAL DISK HAVING DIFFERENT THICKNESS IN AN INFORMATION AREA AND A CLAMPING AREA, AND AN OPTICAL DISK DEVICE IN ACCORDANCE WITH THE OPTICAL DISK, SPECIFICALLY CONCERNED IN FORMING SLOPE-TYPE STEPPED PARTS IN A TRANSITION AREA BETWEEN THE CLAMPING AREA AND THE INFORMATION AREA, AND RECORDING SPECIFIC CODES ON STEPPED PART SURFACES

摘要

PURPOSE: A high-density optical disk having different thickness in an information area and a clamping area, and an optical disk device in accordance with the optical disk are provided to form stepped parts in a transition area assigned between a clamping area and an information area, in order to make the information area thinner than the clamping area, thereby preventing a servo error caused by a collision between an objective lens and the optical disk. CONSTITUTION: A data recording layer recorded in pit patterns is formed in a direction opposed to an objective lens of an optical pickup. A clamping area and an information area are formed in different thickness. Stepped parts are formed in a portion of a transition area in 0.1 to 0.6mm thickness. The information area is thinner than the transition area. When a blu-ray disk(20) is set at a turn table of an optical disk device, stepped parts are formed in 0.1 to 0.6mm thickness. At this time, the stepped parts are made in slope type having a predetermined inclination up to a part before a start of the information area from a part after an end of the clamping area.