| 摘要 |
PURPOSE:To facilitate and ensure the execution of the test for the quality of a disc and the returning of an optical head to an information track, by providing track regions for evaluation on the inside circumference, the outside circumference, etc. of the information track region. CONSTITUTION:A magnetic disc 1 is provided with an information recording region L of tracks of a spiral form or the like and track regions K and M for evaluation of concentric circle-shaped tracks having respective address numbers on the outside circumference, the inside circumference, etc. of this region L. Consequently, tracks of regions K and M are utilized to execute easily and surely desired test and inspection such as the test for S/N of the disc 1. Even if an optical head jumps out from the region L by vibration or the like, the optical head is returned to the region L easily and surely through regions K and M. When the track region for evaluation is provided on either of the inside circumference and the outside circumference of the region L, the same operation is performed also. |
