Optical disc manufacturing method and device, optical disc, and optical disc reproduction method

A read-only optical disc comprising:

• a data structure in which a recording is made in units of a cluster including a row of recording-information bits and an error-correcting code;
• and
• lands and pits formed contiguously to each other along a recording track and a sequence of the lands and pits complies with a predetermined variable-length modulation rule, wherein,
• the disc includes a specific cluster having a disc-unique identifier additionally written thereto by irradiated laser light having a power higher than a reading power level to the lands in the cluster to give the lands a optical property equal to that of the pits,
• the specific cluster has preset in a predetermined position therein a continuous area corresponding to each bit of the identifier, and
• the continuous area has a bit value corresponding to the identifier recorded by lasering on the lands located in positions where an entire bit row will comply with the variable-length modulation rule even if the lands are replaced with pits.

An optical disc producing method of producing a read-only optical disc in which recording is made in units of a cluster including a row of recording-information bits and an error-correcting code, lands and pits are formed contiguously to each other along a recording track and a sequence of lands and pits complies with a predetermined variable-length modulation rule, the method comprising:

• an information bit row forming step of forming a modulated bit row which is to be a land/pit pattern on the optical disc;
• an identifier appending step of additionally writing an identifier to a specific cluster on the read-only optical disc by making pattern inversion to transit a predetermined land in the modulated bit row to a pit;
• a disc master forming step of forming an optical disc master having the modulated bit row recorded therein after having the identifier additionally written;
• and
• a disc forming step of forming the read-only optical disc with use of the optical disc master,
• in the information bit row forming step, continuous areas corresponding to bits of the identifier being preset in predetermined positions in the cluster and lands included in each continuous area and located in positions where an entire bit row will comply with the variable-length modulation rule even if the lands are replaced with pits being changed by the pattern inversion corresponding to a value of each bit in the identifier to have an optical property equal to that of the pits.

A read-only optical disc comprising:

• a data structure in which recording is made in units of a cluster including a row of recording-information bits and an error-correcting code,
• lands and pits formed contiguously to each other along a recording track and a sequence of the lands and pits complies with a predetermined variable-length modulation rule, wherein,
• the disc includes a specific cluster having a disc-unique identifier additionally written thereto after having a land/pit pattern formed thereon by modulating an arbitrary information bit row and error-correcting code for the bit row,
• the specific cluster has preset in a predetermined position therein a continuous area corresponding to each bit of the identifier, and
• the disc-unique identifier is appended to the continuous area by transiting, to pits, the lands located in positions where an entire bit row will comply with the variable-length modulation rule even if the lands are replaced with pits.