PURPOSE: To carry out the operation from the start to the end of reproduction based on a normal reproduction operation when a high-density optical disk is erroneously mounted on an existing CD reproducing device by segmenting a signal recording surface into ≥2 regions having prescribed characteristics.
CONSTITUTION: The signal recording surface of the optical disk 1 is segmented into at least ≥2 regions, the first region A and the second region B. First phase pit strings which are 1.6μm in the spacing between the phase pit strings and ι0.8μm in phase pit length are formed in the first region A. Second phase pit strings which vary from the spacing between the phase pit strings and the phase pit length of the first region A or from a data modulation system are formed in the second region B. The first region A is so formed as to include at least a range of a disk radius 23 to 25mm. The pit strings complying with the requirements specified for CDs are formed in the region of the radius 23 to 25mm in such a manner and the lead-in and lead-out information of the requirements specified for CDs is recorded as the data pit strings, thereby, the operation from the start to the end of the reproduction based on a normal reproduction operation is carried out even when the high-density optical disk is erroneously mounted on an existing CD reproducing device.
SUZUKI YOSHIO
INOUE MASAYUKI
FUKUSHIMA AKIO
