OPTICAL DISC AND DISC CARTRIDGE

摘要

PURPOSE:To make it possible to recognize a disc having high mechanical accuracy by providing the disc with a pass mark of inspection process. CONSTITUTION:An identification mark is imparted to an optical disc 1 having high mechanical accuracy wherein the recording track is aligned highly accurately with the center of central hole. An optical pickup then makes a decision whether the identification mark is present on the disc 3. When no mark is detected, a CPU 5 controls a spindle motor 2 to lower the rotational speed of disc otherwise increases the rotational speed of the disc 1. In other words, a decision is made whether a mark is present or not and a rotational speed suitable to the mechanical accuracy of the disc 1 is selected thus performing a good recording/reproduction.