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

摘要

PCT No. PCT/JP94/02304 Sec. 371 Date Aug. 28, 1995 Sec. 102(e) Date Aug. 28, 1995 PCT Filed Dec. 28, 1994 PCT Pub. No. WO95/18443 PCT Pub. Date Jul. 6, 1995The present invention provides an optical disk 9 with a duplication preventing function, reproducing system 47 for the optical disk 9, optical disk reproducing method, method of fabricating an optical disk original record, and illegal program operation stopping method. An area in which a CP signal 24 is recorded is made after a signal having a constant pattern in the optical disk, the CP signal 24 being produced such that the center of an eye pattern is shifted from the center of the amplitude. In the reproducing system, CP signal arrangement information 25 or a CP preceding signal 26 is 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.