Optical disc recording medium, reproduction device and method and recording device and method for the recording medium

摘要

Main data is recorded by a combination of pits and lands on one side of a substrate (101) of an optical disc (100). A reflection film (102) and a cover layer (103) are layered to cover the surface where the pits and lands are formed on the substrate. Sub data is recorded by a mark formed by irradiation of a laser beam to the reflection film by recording power. In a forged disc produced according to a valid optical disc in which a reproduction signal level at the portion having a mark increases, a mark recording is performed so that the reproduction signal level at the portion having the mark is lowered and the polarity of the reproduction signal at the portion having the mark is different between the valid disc and the forged disc. Furthermore, sub data recorded on the optical disc is detected by the reproduction device and it is judged whether the detected sub data has a value reproduced with a valid polarity, thereby judging whether the disc is a valid one or a forged one.