US Patent 7426164 Disk kind identifying method and disk apparatus

A disk apparatus is for a disk, and a DVD-RW or a DVD+RW can be mounted as the disk. For example, a wobble signal is detected on the basis of a laser beam reflected by a recording surface of the disk. A CPU determines whether a cycle of the wobble signal (wobble cycle) is 32 times or 186 times as long as a data cycle on the basis of a detection result of a detecting circuit. Then, when the wobble cycle is 186 times as long as the data cycle, the disk kind is identified as the DVD-RW, and when the wobble cycle is 32 times as long as the data cycle, the disk kind is identified as the DVD+RW.