DISK RECORD MEDIUM, RECORD APPARATUS AND REPRODUCTION APPARATUS

摘要

PURPOSE: A disk record medium is provided to prevent a beat from be added to extracted wobbling information. CONSTITUTION: In a disk record medium, on a disk is previously formed a groove servings a track. A physical address is written at the track by wobbling the groove. A pre-groove(GV) is formed in a spiral shape, and right and left walls are wobbled according to address information. The walls is wobbled in a predetermined period determined by a wobbling signal which is generated on the basis of the address information. A region between adjacent grooves(GV) is used as a land(L). In a case where the groove is used as a data track, a track pitch(TP) is defined as a distance from a center of a first groove to a center of a second groove adjacent to the first groove. The width of the groove is more than that of the land. The groove is wobbled by a signal whose modulation is completed on the basis of an address, and an absolute address is extracted by performing a PM demodulation to reproduced information. The disk is rotated by a constant angle velicity(CAV) system. The number of wobbling periods of the groove provides a constant linear density(CLD), not a constant angle velocity. The number of carrier periods of a wobbling waveform is fixed at a track-line direction.