Information recording media, optical disc and playback system.

摘要

A CD-ROM (4 in Fig. 1) is provided with an area for forming a character/graphic pattern (14). The character/graphic pattern (14) is formed in such a way that data, which generate on the CD-ROM (4) two sorts of pit patterns having average reflectances different from each other to a perceptible extent, are respectively recorded inside and outside the character/graphic pattern (14). Unless an illegal copy disc is produced by duplicating the legal original disc of the CD-ROM (4) at a very high precision, the character/graphic pattern of the copy disc is invisibly deformed by the discrepancy between the arrangements of the pit patterns of the copy disc and the original disc (4).