| 摘要 |
<p>An optical disc recording apparatus wherein a first modulation signal is produced whose signal levels are switched in a period, which is an integral multiple of a basic period, in accordance with main information, then the light beam to be irradiated onto an optical disc is controlled based on the first modulation signal, and then the pits and lands or the marks and spaces are sequentially made on the optical disc with their length being an integral multiple of a basic length corresponding to the basic period. A data sequence based on sub-information is modified by use of a signal obtained by multiplying a pseudo random number sequence by a predetermined periodic signal, and the recording tracks of pits or marks are so changed as to correspond to the result of that modification, thereby recording the sub-information onto the optical disc. In this way, even in a case of using a pseudo random number sequence for recording of sub-information, the structure cannot be easily determined, so that it is difficult for a person, who tries to perform an illegal copying, to manufacture illegally copied discs.</p> |
