OPTICAL DISC, REPRODUCER OF OPTICAL DISC, DEVICE FOR PRODUCING OPTICAL DISC AND METHOD FOR PRODUCING OPTICAL DISC

摘要

Disclosed is an optical disc on which main information capable of being decoded using sub-information is recorded by arranging recessed and protruding recording marks on a spiral track, and which has a reflective film formed on the recessed and protruding recording marks, wherein first sub-information is recorded while being superimposed on the main information by displacing or deforming the recessed and protruding recording marks or modifying the patterns thereof, and second sub-information is recorded while being superimposed on the main information by changing the reflectivity of the reflective film formed on the recessed and protruding recording marks.  The first sub-information and second sub-information are recorded in the same region from which the first sub-information and second sub-information can be read out simultaneously, and the second sub-information is recorded while being correlated with the first sub-information.  Since the first sub-information and second sub-information are correlated with each other, content information can be read out only when the first sub-information and second sub-information are reproduced, thus enhancing restriction on illegal reproduction, and, since the first sub-information and second sub-information are recorded in the same region, a reproduction time required for reading out the sub-information is not increased.