The present invention provides an optical disc 9 having a copy protection function, which provides a playback device 47, a method of reproducing an optical disc, a method of manufacturing an optical disc master, and a method of stopping illegal program operation, thereby providing a predetermined pattern of signals to the optical disc. A region in which the CP signal 24 is recorded so as to deviate the center of the eye pattern from the center of the amplitude is provided. The playback apparatus detects the arrangement information 25 of the CP signal or the CP preceding signal 26, and then outputs the RF signal. By applying an offset voltage to the threshold value when demodulating the digital signal, the signal is regularly reproduced by shifting the center of the eye pattern away from the center of the amplitude, and if the predetermined offset signal is not reproduced, the function of stopping reproduction is added. have.
展开▼
