Optical recording medium, reproducing system, method of reproducing optical disk, method of fabricating optical disk original record, and method of stopping illegal program operation

Abstract

The present invention provides an optical diskwith a duplication preventing function, reproducing systemfor the optical disk, optical disk reproducing method, method of fabricating an optical disk original record, and illegal program operation stopping method. An area in which a CP signalis recorded is made after a signal having a constant pattern in the optical disk, the CP signalbeing produced such that the center of an eye pattern is shifted from the center of the amplitude. In the reproducing system, CP signal arrangement informationor a CP preceding signalis detected, before an offset voltage is applied to a threshold value to be used in demodulating an RF signal into a digital signal so that the threshold value varies, thus normally reproducing the signal in which center of the eye patter is shifted from the center of the amplitude. The reproducing system has a function whereby the reproduction is stopped when a predetermined offset signal is not reproduced.