| 摘要 |
PURPOSE:To heighten the concentricity of two substrates arranged oppositely at the time of driving and to stably perform recording and reproduction on all of the recording layers provided on the substrates by forming the two substrates movably relatively. CONSTITUTION:An optical disk 1 is formed in a state where the recording layers 3 are set at the inner sides of two disk shape substrates 2a and 2b, and ring shape attractive members 5 and 6 are provided at the inner peripheral and the outer peripheral sides of the substrates 2a and 2b, respectively. Those attractive members 5 and 6 are formed by combining material attracting with each other such as permanent magnet, etc., and can be slided by functioning a magnetic attractive force. Therefore, the quantity of deviation of the central axis of a turntable 22 from that of the substrates 2a and 2b at the time of rotating the turntable 22 on which the disk 1 is loaded can be decided in spite of sticking accuracy since the substrates 2a and 2b are movable relatively. In such a way, it is possible to improve the concentricity of each driving substrate and to perform the recording and the reproduction stably on all of the recording layers provided on the substrates. |
