OPTICAL DISK REPRODUCING DEVICE, OPTICAL DISK AND MANUFACTURE OF OPTICAL DISK

摘要

PROBLEM TO BE SOLVED: To surely prevent a pirated edition from being used by bar-coding the positional information being a kind of an ID for preventing pirated edition. SOLUTION: This is a reproducing device reproducing an optical disk 800 having a first recording layer and a second recording layer readable from one surface side by an optical head, and having the bar code forming striped marks of low reflectance long in the radial direction on a part of the recording layer in the recording areas of the first recording layer and the second recording layer. Then, the device is provided with a first layer/second layer switch means 827 for switching the focus of the optical head to the first recording layer from the second recording layer, a focus control means 828 receiving a command from the first layer/second layer switch means 827 and controlling the focus, a focus drive means 829 driving the optical head according to a signal from the focus control means 828. The device reproduces the signal of the mark existing on the prescribed area by switching the focus of the optical head.